There was a fascinating article in the August/September issue of "Mother Earth News" about making a swimming pool (actually a pond) that would not require any chemicals because the water would be kept clean by bog plants. (Go to www.motherearthnews.com and search the site for 'natural swimming pools.') Has anyone out there actually done this? I would like to try it, but it would be great to hear about other people's experience first. Would the water really stay clean enough to swim in? Are EPDM liners that are rated safe for fish and plants also be safe for people? Would it be better to use EPDM, or bentonite, to seal the pool?
As you can see, I have lots of questions, but have never met anyone who has actually made a swimming pond. Any advice anyone could give would be appreciated!
(I went back and edited this to correct the link.)
This message was edited Aug 8, 2005 10:07 AM
Has anyone made a natural swimming pond?
I made a 30'x18' lined pond with depths of four and two foot deep last year, in the shade of a tall tree, so at best it gets dappled light but does catch the last two or three hours of sunlight, in the evening (It's a quirk here to tinker with making ponds for different purposes... hardy / trop waterlilies, lotus, fish, loafing etc)
Anyway, back to the swimming pond. There is a four foot trench, so I can dive through the length or swim a few strokes along it, however the main function is to be able to loll in the water staring up at the sky and well, just loaf.
Along the shallow depth are planted half a dozen or so hardy waterlilies in pots with mostly clay in them, several are flowering this year. Fertility is very very low on the pond, except for those half dozen plant pots, a few sprigs of anacharis have now formed quite attractive foliage in quiet corners
The water has been quite clear ever since it was filled, the likes of whirlygig beatles, pondskaters and dragonfies were soon to colonise the same night, as for clarity, except for the inevitable traces of fine mulm sediments that drift in the convection currents, though when paddling these can be stirred up some so the water can be clouded. As your skin dries off what traces there might be brush off softer than sand.
As for water quality, well, water companies often supply water that is not fit for fish to live in, however it is considered technically fit to drink... so it is safe to say a pond that is fit for fish to live in, with aquatic plants constantly absorbing trace nutrients and minerals is better than most folk use in their shower, except for the presence of trace amounts of algae, silt, clay, sand and the odd tadpole or aquatic bug...
Regards, andy
Thank you, Andy, for the information and the great link. Loafing and looking up at the sky while immersed in water are two of my favorite things to do. I love the idea of making the "trench" portion of the pond extend lengthwise so you can swim a bit. My pond might be 30' x 100' and up to 10' deep in the deepest portions, with edges as shallow as 2' deep.
You mention the amount of sunlight. Is this because more shade means clearer water? There are a number of tall softwood trees surrounding the area where the pond will go, and a mountain to the south that blocks sunlight after 2 p.m. in winter but doesn't block the sun at all in summer.
More questions: Will my 95-pound Lab tear the 45-mil EPDM liner with his toenails? Will the liner be able to stand up to deer and bears walking on it? Do I need to fence the bigger creatures out? I have no problem sharing my swimming hole with 4-legged creatures, but I don't want them putting holes in the bottom.
Thanks again --
Hannelore
Summer heat and sun is a bit brutal in the Carolina's, the idea of dappled shade through mid day and afternoon is a bit more pleasant, by late afternoon a full sun pond could be well into the nineties
It hardly matters how thick a liner is when weight or velocity is applied to a sharp point on a liner. My choice was to buy the cheapest stuff and keep some seaming tape on hand ready for the day a leak shows up. Being so cheap, it's a lot easier to throw another liner over the old one in future, and pour a clay solution between the liners...
Some folk have bought very expensive liners, put a load of clay and soil in to minimise 'hoof damage', then found it leaks atrocious a few years later...
By keeping the liner cheap, and the pond free of clutter, it's fairly easy for me to take the option of throwing another cheap liner in or patching the odd claw ding. Storms here can flip branches from 100 foot trees to impale a foot in the ground, no biggy if it goes through a cheap liner...
Main damage to a liner here is likely to be from moles, mice pecking at the liner to get water through the Winter months beneath the frozen ground, at or about the water level... The larger a pond, the more area you are going to have to search for leaks when doing routine maintenance...
Regards, andy
Excellent points. We have blazing hot summers here, too, so I'll try to locate the pond where it will get quite a bit of shade.
As far as the liner getting punctured, would bentonite be a better way to go for such a large pond? I don't know much about it and have no idea where I would get it or if we could install it ourselves (with the help of a Bobcat loader). Or -- I've heard of people putting the rubber liner down first, with the bentonite on top of that.
We have an existing good-sized pond with no liner. It is fed by a seasonal creek. The pond gets full to the brim before Christmas, and almost empty by August. I don't know how much of the water loss is due to seeping into the ground, and how much is due to evaporation. (Average humidity here in the hot weather is low, probably in the 20's at most.)
I really appreciate your help!
--- Hannelore
I do not wish to sound like a ‘doomsayer’ but there is a very real potential flip side to the use of natural ponds you may wish to consider. There are numerous waterborne diseases that occur in natural ponds. Typically they occur in ponds that are relatively shallow, warm up a bit and are frequented by birds and other wildlife. Should your pond become a significant reservoir for these biological agents you will run a risk to yourself and to anyone visiting you who also uses your pond. The legal ramifications of someone else’s child becoming ill from using my pond as a swimming hole would, in my mind, be a major factor for not using the pond in this fashion.
So what are some of the issues? It might be as benign as ‘swimmers itch’ (see this website for discussion: http://www.hope.edu/swimmersitch/ ) or it could be something rare but deadly as was just recently reported (see this website for discussion: http://my.netscape.com/corewidgets/news/story.psp?cat=51280&id=2005080521430001763196). And in case that link becomes inactive here’s the lead paragraph of what they were discussing:
“The boys, ages 9 and 7, did not know each other but were both
believed to have been swimming in area ponds before contracting
Naegleria, an amoeba that enters the body through the nose and can
cause a deadly inflammation of the brain.”
Incidently, the mortality with Naegleria appears to be on the order of 99% (200 known cases in the past 40 years with only two survivors) therefore, while very rare it is very deadly.
On another water gardening website we had a lengthy discussion regarding the issue of using our ponds for a swimming pool and I was amazed at the amount of anecdotal information that surfaced regarding people who had health-related problems stemming from swimming in ‘natural’ ponds. Waterborne, associated diseases such as hepatitis, giardia, and cryptosporidium - to name just a few - are not all that rare in both our water supplies and our lakes and ponds. The current push to install so-called “natural swimming pools” fails to discuss these potential risks. Unfortunately, there are insufficient numbers of these installations either in this country or in Europe to perform any adequate, quantitative risk analysis regarding public health issues associated with the use of such facilities.
I guess I would be extremely hesitant to run the liability and the personal risk of using my pond for swimming. I’ve personally had an exposure to ‘swimmer’s itch’ and never, ever want to go through that again.
DRH2, don't feel bad about voicing such a warning. This is just the kind of information I need to know. We live in a rather wild and rural area, and, just like "Field of Dreams," I know that if I build it, they will come -- "they" being deer, bears, turkeys, frogs, snakes . . . not to mention my own dear dog and a host of microbial visitors. We get the occasional stray cow and (our most exotic visitor) even buffalo.
A few years ago I had a summer place on a small manmade lake in New York State. It was shallow (nowhere more than 14' deep), rather warm, not very clear, and had a colony of beavers. Seems like I and a number of other visitors who swam in the lake got an inordinate number of minor infections. I definitely don't want anyone to get sick from swimming in my pond.
An alternative that I've been considering is to build the pond for its beauty, air-tempering qualities, and water-storage capacity (not to mention a place to grow water lilies!), and build a conventional swimming pool right next to it. We could landscape the pool to look like it belonged with the pond, but keep the water separate.
I'd be very interested in reading the anecdotal evidence that you mentioned. Can you provide a link? Or, if that's against protocol here, can you email me? I'm relatively new to DG and haven't received any emails here yet -- is there a message that pops up when I log on to let me know that I've got email?
Again, thanks for your input. Anyone else out there with something to add?
--Hannelore
Yuck -- I just looked at the Swimmer's Itch web site. A chlorinated pool is looking better all the time!
As far as I am aware, there are far more communicable infections and harm to be acquired on land, than there are in a well kept freshwater pond. Lets list a few. Bubonic plague, staph infections, botulism, e-coli, aids, gangrene, tetanus...
You are far more likely to pick up a deadly infection or harm in a hospital, loafing at a beach, falling down the stairs or driving on the road, than doing some pleasant, healthy activity in a well kept freshwater pond
Regards, andy
Yes . . . and it's frequently the thing you never saw coming that gets you, not the thing you stayed up nights worrying about! Thanks, Andy, for your encouraging words. This pond project is still quite a ways off for me, since there are a number of projects that must precede it . . . so I'll spend my time gathering more data and opinions. I, and several family members, are known to throw caution to the winds when facing a body of water, and the dog and I had a lovely swim with the tadpoles in our unlined pond (before it dried up), with no ill effects. Just lucky? Who knows??!!
At any rate, I appreciate input from both camps.
Thanks --
Hannelore
I'm glad DRH2 said his 2 cents worth already. I was shocked and appalled at the beginning of this thread. Have we forgotten why we put chlorine in our drinking water? Yes.... we have all seen and heard about gathering down at the old swimming hole, which was a "natural pond" or stream or whatever. But thats all we hear about, we never hear about the illnesses that resulted. Face the facts... all kinds of organisms, bacteria and the like can and do live in water. Thats not to say they live in all water, but do we really know which is which? To say that a well maintained pond should be safe is very vague. A well maintained pond that is "safe for swimming" means chemically treated water to kill dangerous (as well as beneficial) bacteria.... there are no two ways around it. Testimonials about people who swim in their pond all the time are not sufficient evidence of "natural pond" safety. There are many variables that enter into the equation. For example, a healthy person with an excellent immune system may be able to swim in a pond with dangerous bacteria and never show any symptoms. Another person swimming in the same pond at the same time may not be so lucky. If you need to see for yourself, get a high power microscope and some pond water and have a look.... seeing should be believing.... Tom
PS... Hannelore.... building such a large pond will be very enjoyable. I can only imagine the visitors you will be able to observe making use of your pond!!!
Silver, you might be letting the world of 'speculation', phobias, government and corporate incompetence dictate what you know.
Here I drink water that comes from a well, there is no Chlorine. It is filtered through clay beds which are ideal for eliminating almost every pollution.
By contrast, a few miles away, the local (recycled) city water was shut down a few days because of fecal contamination. You realise, Chlorine goes into the water to kill stuff that should not have been in it, in the first place...
Incidentally, Chlorine does nothing to fix little problems like water recycled downstream of sewage, industrial, farming, golf courses which pound out poisons big time... Chlorine does NOTHING to reduce harm from those poisons in your water.
Yes, you may well have very, very serious problems resisting infection and bacteria if you drink that stuff, check out mercury and pcb toxicity
I go paddle and swim in a freshwater pond where I know what has gone into it, unlike local rivers, lakes, streams, reservoirs and beaches, which are influenced or maintained by who knows how many incompetent interests. Who employ the likes of illiterate migrant labour unable to read health and safety instructions on poison labels
Many of them present the risks of poisons and toxins which you might well fear, residual effects of ddt, pcb's, mercury, organophosphates, lawn poisons etc
I've looked over medical sources as to what risks there are presented by paddling or swimming in well maintained freshwater ponds. It is way, way less than most other environments.
There is way less risk of harmfull bacteria in a well kept pond, than on land, or in any other waterway
One of the main factors in the lower risk is that most of the bacteria we take for granted as being considered 'harmfull' cannot and do not live in freshwater with a natural balance of aquatic bacteria...
>>To say that a well maintained pond should be safe is very vague
Not vague at all. Quite specific, really, if you know what you are doing.
I can wipe out every organism in the pond at will, easily. A paltry dose of Copper Sulphate will more or less disinfect the whole pond for less than a buck, if ever I had any cause for concern.
Certainly adequate for eliminating the parasite 'swimmers itch' plus the snail hosts it relies on for its 60 day cycle. Though that is hardly required, as wildfowl that distribute the parasite do not visit that pond, so that risk is measurably low, in the first place... Not that there are many snails, either, there is a couple of l'il shubunkins there which make snails quite a rarity
As someone who has tinkered in freshwater ponds for umpteen years and never had a health problem that required a doctor in thirty years, I can safely say I'd rather loaf in a pond than most other places.
Eeeew, eeew, eeew, water that requires chlorine. How awful
Regards, andy
This message was edited Aug 8, 2005 4:24 AM
Well... there are exceptions to everything. A natural pond like those found underground in caves are quite safe for swimming and drinking without the use of chemicals. Clay does a wonderful job of filtering water. There are exceptions... not all well water is safe to drink. When humans take this water from the ground or even when they take surface water, there is always a chance for contamination from bacteria, hence the addition of chlorine as a precaution. And no, they do not do anything to remove chemical contaminants from the same water. A prudent person would add filtration to their drinking water source if it comes from "uncontrolled" sources. In the same fashion, a prudent person would not construct a pond intended for use by guests. Study and education on the subject and careful monitoring can produce a pond that is "safer" as you have done. But the facts of life today make the situation a game of russian roulette. The fact is, as you have stated, that your pond has to be maintained, this requires human action, humans are fallible and can make mistakes. You say you control everything that goes into your pond. Unless you have an animal proof cover over your pond, I don't see how that is possible. I can see a large degree of control, but not 100%. It may be a small percent that slips through, but how much does it take? And yes, the good bacteria in the pond can help control the bad stuff. But what is the degree of that control and what happens if the pond is slightly out of balance at the time of contamination? If you are willing to gamble on the odds of maintaining a "safer" pond versus the liability in the event that something goes wrong... so be it.
It kinda comes down to personal choice and responsibility. Would I build myself a pond where I could swim with the fishies?... definitely. Would I build a pond where guests could swim with the fishies... definitely not. Yes... I agree a pond can be made safe for swimming, but there are no guarantees it will stay that way. The same coprorate mind set that has allowed our public water to become what it is is the same mindset that makes it problematic to allow guests to swim in someone's natural pond. The art of building and maintaining a natural pond is not an "exact science". The list of variables is mind boggling as well as ever changing. Proceed at your own risk!!!! Tom
I see this thread has sparked quite a controversy! And mutually exclusive opinions on both sides make perfect sense to me, which sort of, um, "muddies the waters" . . . . !!
I went back and re-read the online article (http://www.motherearthnews.com/Green_Home_Building/2002_August_September/Natural_Swimming_Pools), and I'd like to make a couple of points I didn't make before:
The "natural swimming pools" described in the above article and elsewhere are not totally "natural;" they aren't just holes in the ground with a few plants and fish. Specific steps are taken to ensure water quality, including:
---dividing the pool into "swimming" and "plant" zones, each occupying 50% of the surface area. The plant zone is completely filled with plants (some with roots in the earth, some floating). This quantity of plant material is said to be required (and sufficient) to clean the water.
---placing 4-5" of clean gravel on the bottom of the pool to provide habitat for beneficial bacteria.
---aerating the water via an underwater diffuser for 4 to 8 hours a day, or more if algae becomes a problem.
---installing a surface skimmer to remove debris that would decompose in the water and degrade water quality.
---not keeping any fish in the water, since their debris makes the pool much harder to keep clean. (Other aquatic creatures would appear on their own -- frogs, insects, etc.)
I'm not venturing an opinion as to whether these steps are actually sufficient to make a pond safe for humans to swim in. I'm just mentioning them to clarify what I meant by "natural swimming pond."
I'm 100% sure that failing to maintain the pond properly would make it almost certain to become unfit for swimming. On the other hand, the same is certainly true of chlorinated pools.
A bit of additional information about my specific pond site:
---The land that drains toward the area where the pond would be located is totally undeveloped and is likely to always remain so. There are no houses, farms, or industry upstream or at a higher elevation. There is, however, lots of wildlife, and occasionally cattle wander through (they come up from lower down, or across the ridge from the next valley over).
---In winter, a thick layer of ice forms on ponds in the area.
I don't know if any of this information will change anyone's opinion. As for my own opinion, I just don't know what to think -- that's why I started this thread! Anyway, I appreciate everyone's input.
Hannelore
I think we all agree actually, we just place emphasis on different points. I couldn't find the article you mentioned on the site, so I am glad you mentioned the other points. Good bacteria in the right environment can clean the water... isn't that what a waste water treatment plant does? I see the aerator working all the time at our plant to give the good bacteria the oxygen it needs to do its work. I place my emphasis on the fact that since the plants and aeration is required to keep it clean, that means bad bacteria is there that needs to be disposed of. If there were no bad bacteria present, it would not need cleaning or maintaining. So the question is... are you betting the good bacteria will attack the bad bacteria before the bad guys attack you? Adavisus has apparently been able to maintain a balance where the good bacteria have done their work. No doubt it is possible.
The cattle and wildlife roaming around on the uphill side of the pond would be of some concern, there is no way to control what they have been exposed to. Controlling surface run-off and keeping it out of the pond might help, but then you need to take other measures to replace water loss to evaporation. Like I said before... pond management is not an exact science. Lots of things to consider. Maybe let the silt settle and the issue might clear up some!!!!!... Tom
Also, with the absence of fish, how do you control mosquitos? Did the article say anything about that?
This message was edited Aug 8, 2005 12:45 PM
On a permenant body of freshwater, assuming it is reasonable water quality, a host of aquatic insects that munch mosquito's and their larvae will colonise a pond quite rapidly.
The likes of pondskaters, dragonfly nymphs, whirlygig beetles. Mosquito's will be very difficult to find. Mosquito larvae, eaten.
Similar with 'bad' bacteria that are considered 'unhealthy' they don't survive in a mature pond.
You would have to pound poisons like dimilin in to kill off the beneficial insects, pour significant volumes of organic matter in to decompose and turn the water aneirobic (low in oxygen) enough to stop beneficial oxygen loving bacteria.
Then, you will start to see mosquitos colonising, you may well notice sludge tail worms, and a few other bad guys will be thinking about having a party, too...
>>are you betting the good bacteria will attack the bad bacteria before the bad guys attack you?
I know the good guys have 'sanitised' a pond when I see the evidence of tadpoles of Chorus frogs thriving (they are far more sensitive to toxins and bacteria then we are) When there is a healthy hoard of daphnia about (oxygen levels high enough to eliminate bacteria that like aneirobic conditions) When waterlilies bloom (no fungus or herbicides of any significant level) When fish are entirely disease free and healthy (they have higher water quality requirements than we do)
Plus, there is a complete absence of any mosquito larvae or insects that require aneirobic conditions and no evidence of black sediments
Those instruments are reliable measures of water quality
Regards, andy
http://www.members.aol.com/abdavisnc/swglist.html
Wow, you guys are very knowledgeable about ponds. I am pretty much a total neophyte. What I know about ponds comes mainly from reading, not from experience. I have been feeling a little (actually, a lot) daunted by the idea that I might put a lot of time, effort, and money into building a pond, and then wind up with a smelly, scummy, mosquito-laden mess that wouldn't even be pleasant to look at, much less swim in. However, I'm starting to feel encouraged by your posts. Also, our existing pond, which was here before we bought the property, receives no care whatsoever from us, and it looks very healthy -- crystal-clear water, thousands of dragonflies of various types, happy tadpoles (I don't know what kind), and lots of water insects. Very few mosquitoes.
In case you were wondering, "Why doesn't she just use the pond she already has?" -- well, we do, but it is too far from the house to see and enjoy every day, and it dries out almost completely by Labor Day. When the winter rains start, it fills to the brim and is lovely for 6 months.
I'm sorry my original post provided the wrong information for accessing that online article. I went to the website myself yesterday (www.motherearthnews.com) and found that you must search for 'natural swimming pools' --- NOT 'natural swimming pond'. The article also has a couple of references that I will look into. Also, I believe I have the article itself around the house somewhere -- not the online article, but the print article from the actual magazine. If memory serves, there were quite detailed instructions for building the pond. If I come across it, I will let you know. I could email it to anyone who is interested.
Hannelore
For those of you who are following this debate I apologize for the length of this post which follows. Frankly, I considered just walking away from this thread but so much disinformation was being presented that I thought I’d wade in one more time (you can ignore the obvious pun!).
First, the caveats regarding where I am coming from, credentials, etc. I do not own, operate, or consult for any companies involved with installing, constructing or maintaining so-called “natural ponds” in the context of swimming pools. I do not have any economic interest invested in such companies nor in companies that may be considered to be a opposed to their viewpoint or implementation. I am a Professor of Civil & Environmental Engineering at our University. Along with the usual advanced degrees, doctorate, etc. related to the associated subject areas I have published scientific papers in refereed journals as well as participated in research projects that I strongly suspect are germane to the topic of this thread. I have taught courses (undergraduate and graduate courses) in applied Water Chemistry as well as Environmental Systems. I am also Board Certified in Industrial Hygiene (Ret’d) which involves a bit of understanding regarding toxicology and physiology as well as the interactions of the human body with it’s environment. You will note that in the majority of my previous posts that I tend to rely on scientific papers, opinions from academic institutions or actual, published data simply because this information is usually vetted by the process of peer review to be as objective as possible and relying on scientific fact rather than personal opinion or wishes. So. Let’s play.
The comment that you are more likely to pick up an infectious disease from “land than from water” is in error. The majority of health-related issues as tracked by morbidity (illness) and mortality statistics compiled by the Centers for Disease Control (CDC) and the World Health Organization (WHO) clearly indicate that waterborne diseases far out weigh other sources. But there is also an error in the conceptual model indicating land-based versus water-based. The typical model used in discussing Environmental Health is Source or Reservoir —>Transport or Vector —>Host or Receptor. In the context of this thread water is the transport vehicle or vector not necessarily the reservoir. You will notice in the website listed above regarding ‘Swimmers Itch’ that there is an intermediate host required for the progression of the disease - namely, snails. Both the CDC and WHO had, at one point, a service that you could subscribe to and receive daily e-mail announcements regarding the outbreaks and cases regarding specific diseases within this country as well as world-wide. After several years of dealing with this data (typically 5-10 e-mails a day) you rapidly begin to realize the number of reported outbreaks related to water-borne Environmental Health issues regardless of whether you actually compile the statistics. And here’s another part of the problem: the reports represent only a small proportion of the actual cases, i.e., there is significant under-reporting of the actual morbidity and mortality rates. For example, you go swimming in your private pond or at your camp and a few hours later you may have stomach cramps that pass after a half day or so. That will never be reported in the official databases. Or, as in the case of my next door neighbor, this past Sunday morning we were chatting and oh, yes, by the way - she showed me what her 10 year old daughter picked up swimming the other day out in the lake. It was a significant staphylococcus infection that resulted in her having to have her thumb lanced. That probably won’t make it’s way into the CDC database either. Health-related incidents in public pools, beaches and similar public places are generally reported because it is required by law; individual illnesses, unless on a specific watch list, are not reported except as generic illnesses without specific link to source or reservoir. Therefore you should view health-related data as a potentially, significantly understated problem - specially with respect to waterborne agents. The use of the terminology as “the world of 'speculation', phobias, government and corporate incompetence dictate what you know” indicates a lack of scientific competence or at least a lack of understanding of the specific, scientific issues and databases. Or alternatively, it indicates just plain wishful thinking with no quantitative methodology nor the reliance on actual, factual data from vetted, scientific resources.
I specifically did not list the numerous waterborne diseases in my previous posts. That list is enormous. But rather I chose two ends of the spectrum - a rather benign but very annoying disease such as swimmers itch versus Naegleria which has a very high mortality but relatively low morbidity for the data reported. I could just as well have discussed, in detail, Cryptosporidium or Giardia. Both are waterborne, both have been linked to very significant outbreaks in Environmental Health and are not necessarily linked to contamination of water supplies from sewage or other anthropogenic sources. Or if you wish, consider Cholera, Typhoid, Hepatitis, etc.. There are literally hundreds of waterborne diseases that can appear on our doorstep. True, some are definitely linked to fecal contamination of our water supplies. Which brings us to another point. If you talk to anyone who is involved with running and operating a public swimming pool you will discover several interesting facts. 1.) Wading pools - the pools used for toddlers - generally are required to run much higher chlorine levels than swimming pools both of which are much higher than what we typically run in our municipal water supplies. 2.) Toddlers, when placed in a pool, will quite often pee in the pool and it is not unusual that they will also poop in their swim suits/or diapers. This is a fact; I know it because I’ve dealt with it and seen it. So here you are with your nice, natural pond and along come your friends with their 12 month old toddler. Guess what you are quite likely to have thrown into your pond/pool??? However, the sources of your pool/pond contamination are not limited to toddlers - adults tend to leave their bit of contribution too! Now add in what Mother Nature sends your way: bird poop, swimmer’s itch, etc. Your pond is not a closed system isolated from input from the environment but is, as pointed out by Tom, an open system. It is however, a closed system with respect to the amount or volume of water available for dilution of the input. This is not under the heading of ‘speculation’ but has been repeatedly verified and quantified in good quality, peer-reviewed, scientific literature. It is not incompetence - that is usually the claim by those who lack the fundamental understanding of the methodology in scientific research.
Another concept that is presented is that a good, well designed natural pool/pond will self-cleanse and therefore maintain perfectly clear, clean healthy water. I take particular exception to this concept. Many diseases that impact directly on human health are host-specific. E. Coli is an indicator organism; it’s presence usually indicates the POTENTIAL for human or at least mammalian waste contamination in a body of water. It’s use as an indicator of contamination has been argued by scientists for many years. In fact, several EPA scientists were involved in a small study in my lab dealing with alternative microorganisms as indicators to help separate fecal from non-fecal contamination. E. Coli used to be considered a non-pathogen or at worst an opportunistic pathogen without tremendous health consequences up until about the mid-eighties with the discovery of E. Coli var. 0157:H7 which was clearly a pathogen by the usual definitions. Since then there are other variants of E. Coli that have been found. Why the emphasis on E. Coli? Because it is used as an “indicator organism” meaning that we believe that we see it that it represents a POTENTIAL for waste contamination since it is present in the guts of all of us. Now the more interesting points: Generally it has been assumed that E. Coli exists in ratio on the order of 10,000 or so to 1 with respect to actual pathogens. Thus if you only found one E. Coli organism you had a pretty good probability that it was unlikely that you would come in contact with any pathogens - note that it should not be interpreted as coming in contact with zero pathogens! However, studies conducted on E. Coli’s PERSISTENCE in the environment indicate that the ratio can change significantly. Will some of the contamination be removed via the typical predator/prey hierarchy in your ecosystem? Yes, you bet. But at different rates for different microorganisms and in some cases not at all since the rate of growth will slightly exceed the rate of predation. At this point, if you wish more information you should borrow a copy of a good text on Environmental Microbiology such as “Microbiology for Environmental Scientists and Engineers” Gaudy & Gaudy, McGraw-Hill. There are numerous texts out there so you don’t have to have this specific one but you do want one that deals with Environmental Microbiology and not just General Biology. The point is this: the rate of clean-up or reduction in numbers for E. Coli follows that for some pathogens but for others it does NOT! In some cases, specific pathogens have been found to actually increase slightly in number in the external environment (free of any other source of input). But the second major point is that natural processes that do cause a decrease in number typically take days not seconds or minutes! Remember the wading pool? We run high doses of chlorine in there so that the microbes (and potential pathogens) are killed off in seconds or minutes. This has been confirmed via numerous studies and is therefore the basis for requiring such high chlorine doses. But even as careful as we are, using a very powerful disinfection agent - you can call it a microbial poison if you wish - some microbes get through. Now let’s try the same with your natural pond/swimming pool. If it takes days - not seconds or minutes - to kill off the pathogens what’s the likelihood of potential exposure? If some of those pathogens are not killed off... well the conclusion is obvious. You can scoff; you can rale about this all being supposition BUT where is the published, quantitative data to support your argument?? There is published, quantitative data on the rate of persistent of specific pathogens in the natural environment - not just indicators such as E. Coli.
The concept that I have “not seen disease in my fish; that I see dragon flies”.. or whatever you see in a diverse ecosystem does not in any way mean that the water is safe from a human health standpoint. I can show you watershed after watershed where the water is clear, sparkly, cool; no human habitation on the watershed; no industrial pollution – but if you were to inadvertently swallow that water you would become ill. The size of most of the microbes involved in human disease (excluding viruses and prions) are generally in the size range of 0.5 to 5 microns. You CAN NOT SEE THEM IN YOUR POND! And if they are present then they may in fact have no impact on the health of your fish, the plants or the rest of the bio-ecosystem in your pond because of host-specificity! This is scientific fact, not wishful thinking. As an aside, mosquito larvae require an aerobic environment. They typically float to the surface and in the latter stages breath through a small tube that extends through the water to the air. But in earlier stages they will die if they are in an anaerobic - aneirobic ?? - (no oxygen) environment. Yes, they prefer stagnant water – that means non-flowing or non-moving; it does not mean anaerobic.
Now the final issue. I hope I have clearly stated that your pond - from a standpoint of Environmental or Human Health - is not a risk-free environment. What the specific risk is to each of us depends on our own personal health, how the pond is used as well as the ‘visitors’ to the pond - invited or not. Should a friend or the daughter of a friend happen to visit you and come down with something that THEY (not you) attribute to your pond what then are the liability issues? Unfortunately we live in a litigious society; we hire lawyers to sue over a variety of issues some of which are highly important, some of which are frivolous. But to defend yourself against such legal action does incur a cost. I cannot say whether this cost is worth it to you to be able to swim in a pond/pool that is free of chemical disinfectants - only you can decide whether that is a risk you are willing to take. But that risk is NOT negligible as has been suggested. The information currently available for the natural swimming pools lacks any scientific data from third party, independent investigators (people not paid by the industry to scientifically investigate the efficacy of their systems) supporting either the rate of clearance of potential pathogens or the long-term cleanliness of such systems. Such information cannot be inferred without direct, quantitative measurement. Anyone wishing to install or use such a pond has to make their own assessment of the risk and benefits associated with such an installation. It is not my point or intention to say it is wrong to do so. But be sure that you are assessing your own, personal risk based on the best hard science available using peer-reviewed scientific publications rather than industry hype and wishful thinking.
Again, I apologize for the length of this posting. I will not bother to post on this issue further.
okeydoke, I get the drift.
a) You have no personal experience of making, maintaining and using a freshwater swimming pond with a reliable water source on private property
b) You have no relevant second hand sources or data.
c) You seem to confuse risks, such as introducing statistics of organisations who record data that focuses on habitats probably irrelevant to a private freshwater pond...
d) Come on, if you are going to mention Naegleria, Cryptosporidium or Giardia, you really have to say what the morbidity rate is, in a way that folk can comprehend. Does it make you an intsy wintsy bit poorly... do they compare with casualties from snake bites? lightning? West Nile Virus? Accidents in the home?
Lets examine West Nile Virus, this year in the Carolinas, six million people, one reported case, (no serious consequences) Lots of hype and nonesense in the junk science media
Anyways, here's some real observations (with sources) from medical sources as to what risk are presented by: Naegleria, Cryptosporidium or Giardia...
judge for yourself how the GOVERNMENT HAS FAILED to set competent standards for DRINKING water.
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Cryptosporidiosis: People with normal immune systems are generally not at risk and improve without taking antibiotics or antiparasitic medications. For people with compromised immune systems this can be a dangerous disease.
The parasite is transmitted by ingestion of oocysts excreted in the feces of infected humans or animals. The infection can therefore be transmitted from person-to-person, through ingestion of contaminated water (drinking water and water used for recreational purposes) or food, from animal to person, or by contact with fecally contaminated environmental surfaces.
There is considerable circumstantial evidence that low level (non-epidemic) transmission of Cryptosporidium species through drinking water may be occurring throughout the United States. Recent studies indicate that Cryptosporidium oocysts are present in 65% - 97% of surface waters (rivers, lakes etc.) tested throughout the country
Data from the outbreaks suggest that compliance of utility companies with state and federal standards for water treatment may not be adequate to protect citizens from waterborne Cryptosporidiosis. Moreover, recent surveys for the occurrence of Cryptosporidium oocysts in fully treated (disinfected and filtered) municipal water demonstrate that small numbers of oocysts were able to breach filters and were present in tap water in 27%-54% of communities evaluated
Giardiasis
The use of an appropriate antibiotic for seven days is usually highly effective in relieving symptoms and curing the disease
What is Naegleria fowleri?
Amoebae that live in warm water, soil, and vegetation around the world. N. fowleri may infect humans when water is forced into the nose by diving or jumping into, or swimming underwater in warm, fresh water, stagnant ponds or lakes, or inadequately maintained public heated swimming pools. Springs are considered safe because their water temperature consistently remains below 80 degrees, and the organisms need hotter water to thrive.
Naegleria fowleri is a ubiquitous free-living ameba, which is the etiologic agent of primary amebic meningoencephalitis (PAM) Most N fowleri infections have occurred in children and young adults who have had recent exposure to swimming or diving in warm fresh water.
As of October 1, 1996, 81 cases of N fowleri infection were reported in the United States. Cases have been reported along the east coast from Virginia to Florida, as well as in California
Sources:
http://www.cdc.gov/ncidod/dpd/parasites/cryptosporidiosis/crypto_sources_of_infect.htm
http://www.cdc.gov/nasd/docs/d001201-d001300/d001214/d001214.html
http://www.emedicine.com/ped/topic2807.htm
http://www.cdc.gov/ncidod/dpd/parasites/cryptosporidiosis/crypto_sources_of_infect.htm
Naegleria does seem to be about the most lethal bacteria specific to fresh water, some 95% fatality rate. With 81 cases recorded in the usa (250m popn) The odds of catching it is somewhere in the region of over 3,000,000 to one against
The probability of it transmitting to an isolated pond would depend on it surviving a ride on a bird and finding a pond consistently warmer than 80°f to thrive. You would have to inhale the bacteria through your nose to acquire it
An effective treatment of chlorine or copper sulphate is likely to eliminate any risk
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The references to e-coli in a pond seem a bit iffy, bearing in mind it is just as likely to be present on a lawn or on a pet, by which criterion, the risk of using a freshwater swimming pond is no higher than cutting the grass or keeping a pet ...hohum
Quite frankly I'd much rather consider information from a doctor with first hand experience and knowledge of infection and research medical databases such as the BMA (which I have done) long before I even take your 'knowledge' as anywhere near relevant to measuring the risks associated with a private freshwater pond.
One fact I can pass on to Hanna, on a hot day, a lined freshwater pond is a very pleasant amenity indeedy :)
Regards, andy
This message was edited Aug 10, 2005 4:29 AM
Actually there is a trend towards natural swimming ponds. We plan to install one over the winter.
http://totalhabitat.com/P&P.html
http://www.sarnafil.co.uk/pdf_waterproofing_natural_swimming_ponds_brochure
http://aquahabitat.com/ponds.html
You do not have to use chlorine per se there are other ways to sterilize ponds. I myself have swam in all kinds of lakes and ponds. So far I have never gotten ill from doing so. In fact on Home and Garden television they had several ponds that used alternative methods .
Thanks for the links! I will enjoy exploring them. Good luck, Shadowgirl, with your pond.
Hannelore
Well, this is certainly some read.....very good on all points.
However, I really like the side-by-side pool idea. It is all the rage here in Fl anyway to paint pools dark blue now so that they look bottomless. That would be great for you and you could still have plants and rocks around, but just not in the chlorine of the pool. The two pools certainly could be made to look seamless. This way you would have the best of both worlds.
Just a thought. Good luck with whatever you do. It certainly is a major undertaking.
Hap
Thanks, Hap! My next quest is to find info on how one could make a homemade swimming pool that is just as safe as a pool that a contractor puts in for you. I mean, the dedicated do-it-yourselfer ought to be able to set up a skimmer box, pump, filter, and chemical dosing routine . . . it just doesn't seem that complicated to me. I've already built a 10' waterfall, which worked out just fine, and it seems like the water purification setup is something that could be accomplished with the advice of an equipment supplier who knows what is required. But maybe I'm all wet ????
We can do our own excavation, running of pipe and conduit, and final landscaping. I would have a qualified electrician do all of the electrical work.
Whatever we do, we won't do it for 1 to 2 years -- but I'll post pictures when it's finished!
Hannelore
http://www.nationalpoolwholesalers.com/order.asp
is just one link I found on Google, "making a swimming pool" search. There is no sense re-inventing the wheel, I always say....LOL
Good Luck.
Hap
And don't forget the pictures.....
Hanne and Hap,
we can learn from each other as we are going to do it ourselves. I have discussed this several times with the guy that manages AKT, a wholesale pond materials supply. I know that my friends pond is a liner over a wooden support, which I assume is a We have clay soil that would probably work but then I have had some problems with the clay liquifying around the edges of our koi pond.
You could always use a UV filter but it would be costly for a big enough one and probably to maintain. Hydrogen Peroxide is an excellent for cleansing.
The swimming ponds on HGTV had fish and plants but I don't think that is the way we are going to go.
http://www.river-swimming.co.uk/julia.htm
This link has a step by step process for building a totally chemical free swimming pond.
http://www.gardenworld.co.uk/swim.asp
This site has some drawings about designing a pond.
http://home.bendbroadband.com/Ponds/
This message was edited Aug 13, 2005 5:05 PM
Wonderful, wonderful links. I've sent for the kit from National Pool Wholesalers for customers who aren't quite sure that they're up to the task of building their own swimming pool . . . and I'm hoping to pay a visit to the folks at Spring Creek Aquatic Concepts in the Portland area when I come up for the Pacific Northwest Roundup. (Who knows -- I might wind up with a trout pond AND a swimming pool!) I'd love to see the progress of your pool, Shadowgirl. Be sure to take lots of pictures to share!