Rainwater harvesting

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Rainwater harvesting

Postby Joe Hillshoist » Sat Nov 10, 2007 8:29 pm

In Australia the majority of homes without mains water use rainwater harvesting to provide for household water needs.

Basically a large tank, anywhere from 5 to 25 thousand litres on average, but tanks come smaller, and larger, stores water collected from roof surfaces during rainfall.

The roof of the house, and any outbuildings such as sheds, garages etc etc provide an area for collecting the water, and its diverted using guttering around the eaves, and pipes, into the tank.

Unless terrain is perfect, (ie you have a roof, and the tank at a higher elevation than the plumbing in the house) you will probably need a pressure pump of some sort maintain water pressure inside the house. the best ones are usually impeller pumps with a bladder and pressure switch to maintain a minimum pressure. Theres nothing worse than a shower that dribbles, and only dribbles. (If you are relying on your own water showering should be short and the pressure as low as you can stand most of the time, but sometimes its good to get hammered by hot water, esp if you have been working hard and are covered in filth.)

The best guide I have found on this is here:

http://www.ircsa.org/factsheets/Cunliffe.pdf

It covers everything fairly well.

Far better than I could have.

Basically you want to keep the water of good quality. Especially if drinking it. The best filter you can find is a good idea, although I don't have one. But after 10 years using the same water supply I guess my body has adjusted to whatever minor organism/bacteria/other minor pathogens might be in our supply. I am not recommending being that slack to anyone else tho.

The main sources of contamination are obviously the roof, and guttering. If the tank is sealed to the outside save inlet and outlet ipes then nothing should get in there. If your tank is a below ground tank then make sure it keeps its integrity as soil borne contaminants are a much gretaer threat.

Roofing material has to be kept free of toxic substances, ie the material itself (no lead paint for example), airbourne contaminants such as soot/smoke from an indoor fire, from persticide and herbicide spraying in the area, general air pollution etc etc. The link above covers all this in much greater detail with more clarity. Animal waste, ie bird crap, etc etc is another potential hazard. Thats why post tank filtering is probably your best bet.

These days the majority of our roof catchment is under a massive avocade tree so we keep our rainwater disconnected. We fill our tank from a bore/spring set up and that water is pretty good as well. We disconnected the rainwater after someone who stayed with us got Guiardia (sp) a water bourne nasty that is primarily transmitted through bird crap. We never suffered from it tho, but its not worth giving visitors the disease. We could have cut down the avocado tree and removed the the problem, but the avos are awesome, and the tree produces hundreds every year.

Its a matter of prioritising. If we didn't have the groundwater to rely on (something many Australians don't have) the avo tree would have to go.

Keeping the gutters clean of leaf litter and sludge (from airbourne dust build up), and making sure they drain well removes another source of contamination. There are products available today that claim to keep leaf litter out of the gutters. Some sort of plastic mesh will probably do the trick as well.

Also a firstf flush system is a good idea. About 1 to 2 mls of rain should be enough to clean the roof of crap. A fit flush system is a storage area that fills before allowing water to enter the storage tank. It should have the worst of the gunk in it.

There a diagram of one here. You can probably rig up your own, or if necessary buy one somewhere.

http://www.rainharvesting.com.au/first_flush_water_diverters.asp

About 20 to 25 litres should do the average roof. I think you want 1 to 2 mils of rainfall to really clean it, and its about 1 suare m by 1 ml to get a litre, but check those figures.

What else? Materials... Plastic, Fibreglass, and Steel are the best bets, all treated to food quality standards. AFAIK the only manufacturers of rainwater tanks are in Australia, as we seem to have the worst groundwater in the world. I wouldn't know where to get any in the US. At the moment there is a backlog in Australia too, cos of the drought and a rebate on water tanks that the government has introduced, so you might be waiting a long time for one from here, not to mention the shipping costs. perhaps the best bet would be to get one fabricated out of steel, with a lining inside (the PDF goes into details on the sort of lining.)

That is the basic idea, but read the first link to get a thorough ide. Its a lot clearer and more orderly than what I have posted.

There are a couple more links here that are worth going over. They are from the US so should be more useful re local information.

http://www.harvesth2o.com/

http://www.harvesth2o.com/faq.shtml



I know this is a bit higgledy piggledy but read the links and if you need any further info feel free to ask.
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Postby Sweejak » Sat Nov 10, 2007 9:27 pm

Great links.
Wiki has a fairly nice set under "Rainwater tank". Including the rather shocking information that collecting rainwater in Colorado is illegal.

http://en.wikipedia.org/wiki/Rainwater_tank

Our system uses three filters, a roof washer, and two progressively finer particle filters. Lastly, we have a device that was developed for dialysis to kill germs
http://www.steamvaporclean.com/sanitron.htm
The bulb burned out a year ago after running for maybe 5 years and we haven't bothered to replace it.

Rainwater was included in the design of the building so we have what is called a butterfly roof, I suppose you would want to be in a snow free area to even consider this, but the roof has been loaded with hail and a little bit of snow. It's a very strong roof being made of SIPS (structural insulated panels). There is only one short gutter, no trees dropping leaves on the roof, and it's situated to make solar easier.

There are some shots of the building here.
http://gallery.mac.com/kaaawa#100048

The roof has other advantages, namely letting in a lot of light and ventilation and we believe it creates a standing wave that results in a very nice volume of air being fed to another building downwind.

We went overboard on tanks and bought two 10K gallon fiberglas tanks. I liked the idea of having them modular, if one fails we have another, and we can add another if need be. They were by far the most expensive part of the system.

Having no city water we were faced with wells or rainwater, so we were going to be spending considerable sums no matter what. The rainwater is just wonderful, probably one of the best decisions I've ever made.
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Postby Joe Hillshoist » Sun Nov 11, 2007 2:35 am

Wiki has a fairly nice set under "Rainwater tank". Including the rather shocking information that collecting rainwater in Colorado is illegal.


I know, I can't believe that. One of the dumbest laws of all time IMO.

Awesome looking place BTW.

Was it easy to source rainwater tanks in the states?
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Postby Sweejak » Sun Nov 11, 2007 3:19 am

Yes, the tanks are local, well, regional. They were made in Giddings Texas.

I had help in this, a fellow called Rainman who designed the system did the plumbing and what little engineering is required. He loved the butterfly roof.

There is a fairly strong local grassroots effort here. The water boards give lip service, but being tools of the developers they fear it.... until they can tax it or control it. The city often proposes things but they get shot down in the state Capital. The ranchers are often at the forefront.

There are some good programs though. But in the end this is what we get:
http://homepage.mac.com/kaaawa/Hamilton ... um112.html

Much of the building is built with recycled bits of old Austin. I had the good fortune to find a maniacal recycler, Loco Lopez, and we got a lot of industrial quality stuff for pennies. The Australian, Glen Murcutt was an inspiration for some of the design as well as locals.

Here are some local links:

http://rainwater.org/rainwater_stories.html

http://www.cmpbs.org/

http://www.wildflower.org/exhibits/

http://www.wildflower.org/

There is a documentary out which is about the long battles we have had.
http://festival.sundance.org/filmguide/ ... ?film=4670
I haven't seen the film but I can assure you that the degradation was not unforeseen.
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Postby chiggerbit » Sun Nov 11, 2007 11:55 am

Wow, excellent information, Joe and Swee, thanks! I had vaguely considered putting a tank in, but I see I would have some serious problems to think about first, not the least being across the road from a farm field being rented to a farmer who thinks that if a little chemical is good, a lot is better. Then there's the problem of being surrounded by trees.
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Postby Sweejak » Sun Nov 11, 2007 12:50 pm

I don't know what to do about the chemicals. You might still consider using some for irrigation.
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Postby chiggerbit » Sun Nov 11, 2007 1:39 pm

Hmmm, well, I think the ponds I had made a few years ago might work for that.....maybe. My problem is that my land is extremely hilly ("hilly" doesn't begin to describe it) , and the garden had to be put on a different hill because there was no room near the house. Well, that and all the trees. Heck, I don't even swim in the ponds anymore, after I got a permanent case of tinnitus, I suspect from swimming in the pond near the house--it was a very hot summer, and I spent a lot of time floating on one of those air mattresses. All but one pond are filled with runoff from the farmer's fields. I had a total fishkill this past winter, I suspect from the chemicals. I suspect the chemicals even of almost killing off the cattails in the ponds this summer, and they're hard to kill. Maybe I shouldn't use that water on the garden, either.
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Postby Sweejak » Sun Nov 11, 2007 1:57 pm

Wow, what a bad situation. That really limits your sources. Are you using well water?
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Postby chiggerbit » Sun Nov 11, 2007 2:04 pm

No, I'm hooked up to one of those rural water systems that are similar to city systems. The source of the water is probably 75 miles from here, a damned watershed, with a string of water towers. When I built, I considerd having a well put in, but I was told by the locals that deep wells often run into coal, so the water tastes bad. Since wells are so expensive, I thought better of it, didn't want to gamble. If I ever get enough money together, I might still do it.
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Postby chiggerbit » Sun Nov 11, 2007 2:18 pm

This is the back end of my property, where I hide the bodies:

Image
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Postby Sweejak » Sun Nov 11, 2007 2:35 pm

Well, looks like you have a cave. Pennsylvania? W. Virginia?

In light of the debate about libertarianism I'm wondering if your water supplier is 'privatized', and how well it works. It sounds like a big operation.

Also, I've been having tinnitus too, since about the time I installed a wireless router. I don't know if it's related. You'd think it would be more logical to assume it's because of the noisy equipment I've been around, but I always wear noise suppression. Do you know of waterborne organisms that cause tinnitus?
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Postby chiggerbit » Sun Nov 11, 2007 2:48 pm

Heh, keep guessing. I'll tell you soon if you don't get the right one, wouldn't want you to be guessing through all fifty. It's not a cave, just a chimney formed by a chunk of rock that split from the face.

Not sure about water-borne causes. I kinda figgered nerve damage from the chemicals.
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Postby chiggerbit » Sun Nov 11, 2007 2:54 pm

Well, I guess this will give it away, but this is the water system I'm on:

http://rrwa.net/page5.html
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Postby chiggerbit » Sun Nov 11, 2007 10:18 pm

You guessed flat-corn-country-Iowa, right Swee?
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Postby Joe Hillshoist » Sun Nov 11, 2007 10:39 pm

Thats a beautiful spot chig.
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