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Do it yourself water cisterns that AREN'T made out of concrete??  RSS feed

 
Destiny Hagest
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Does anyone have any information on this? Much Googling and even searching on Permies didn't yield me any results, am I missing a source of information on this? For our one day dream house, we plan to plumb almost exclusively with rainwater, which means we'll need plenty of water storage to plumb into the house. Poly tanks are pretty expensive when you get into something that big (I'm thinking 5 10,000 gallon cisterns are needed, very tentative estimate), and I hate hate hate concrete. I know it can be very practical in a situation like this, but it's incredibly expensive and cumbersome to work with in an off the grid scenario.

Anyone have any ideas? I toyed with the idea of using some kind of clay composition, but obviously it needs to be something that's burrow proof and water safe. Am I SOL?
 
Jennifer Wadsworth
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So I guess the DIY aspect of this makes metal cisterns out of the question. Otherwise, there are metal cisterns that size.

From: http://www.watercache.com/blog/2011/12/residential-rainwater-catchment-tank-installation-deal/



I ran across this really intriguing plastic-lined bamboo cistern the other day in my internet travels. These would be smaller cisterns due to materials.

From: http://www.eng.warwick.ac.uk/dtu2/pubs/rn/rwh/cs19/cs19.html

 
William Bronson
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The VelaCreations folks post here and they have tech that will exactly adress your conundrum.
In a nutshell they use sheet metal bolted together into a circle, with a flexible inner liner.
 
Abe Connally
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Here you go, the cheapest, easiest, large potable water storage method around:


A few people can make one of these in 2-3 days. It requires basic skills and a drill. It's about 6,000 gallons of water at those dimensions.

We do make a concrete roof, but you can do a metal one (look for a grain bin lid) or a fiberglass one. The concrete roof we make is super thin.

Here's the full instructions: http://velacreations.com/water/water-storage/313-cistern-howto.html

You can replace the sheet metal with a wire mesh, and the potable liner with EPDM for a cheaper tank for irrigation:


 
Abe Connally
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Location: Chihuahua Desert
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Alternative sources of liners for non potable tanks: swimming pools. Old above ground swimming pools can be found for free or super cheap on Craigslist. And even if you can't find them locally, google for replacement liners, they are considerably cheaper than anything else. I recently made this tank, which is about 7,000 gallons, and the liner was free. It's no good for potable water, but fine for animals or plants.


http://velacreations.com/blog/378-3rd-tank-finished.html


Something to consider is that your roof is where a lot of cost and labor are involved. If you can find a local source for roofs, like fiberglass satellite dishes or grain bin lids, make your tank to fit that roof. It makes everything a lot easier and cheaper. The wider you can make the tank, the cheaper it is in terms of liner and wall cost.

All together, we have 3 x 7,000 gallon tanks, 2 are potable water for the house, the other is strictly for irrigation. Then, we have a 8,000 gallon tank for the barn, which is plenty of water for over 100 rabbits, 50+poultry, pigs, donkey, etc. (we actually only use about 1/3 of this tank each year)

We live completely on rain catchment.
 
Abe Connally
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In my area, we get about 25 inches of rain a year. Now, without an external roof, that won't fill one of these tanks all the way. If, however, you made a 3ft eave all the way around the tank, you double the surface area of the tank roof, and the tank can then fill itself on 25 inches a year. So, it could be a standalone solution.
 
Destiny Hagest
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Wow! I am loving all these ideas! You can always count on some permies to have a solution All of these look pretty affordable to build too. We live in central Montana, where winters can get to -45 (it sure did this year), so I'll definitely need to winterize the hell out of whatever we end up doing. Plus we intend to plumb a water main into the bottom of the cisterns, join them at a central water line, and have them go into the house for year round plumbing. We're hoping (and fairly sure) that we will end up with some very slanty slopey property so we can gravity pressurize the lines. Trying to use as little energy as possible for the water supply. I'm thinking we may have to bury that tanks pretty far down (like 7 feet) to avoid freezing, and then insulate like crazy. There's a lot of rock around here so we would need to be sure that whatever material we wound up making the cisterns out of could stand some occasional poking and prodding from rocks and such. I'm wondering if maybe we should come up with some kind of a cob-esque thermal mass material to put around the bodies of the cisterns to both protect and insulate them?

Reading Art Ludwig's Greywater Oasis book right now and my brain is churning out ideas faster than I can comprehend them. Will definitely be looking into these cistern designs more for that purpose too!
 
William Bronson
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If you intend to bury the tanks, a few layers of used carpet might be all you need to protect the liner. I would be inclined to make the tank long and narrow, to make covering it cheaper.
Most building materials get cheaper(or free) the shorter they are.
Each tank you build is another set of fittings, so one large one could be better, on the other hand that would put all the all eggs in one basket.
 
Abe Connally
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William Bronson wrote: If you intend to bury the tanks, a few layers of used carpet might be all you need to protect the liner. I would be inclined to make the tank long and narrow, to make covering it cheaper.
Most building materials get cheaper(or free) the shorter they are.
Each tank you build is another set of fittings, so one large one could be better, on the other hand that would put all the all eggs in one basket.


Do not deviate from a round tank. The forces on the sides change and you will have to spend extra re-enforcing the sides to handle to pressure. Round is sound.

We use screened sand for the base with a few layers of a protective material to protect the liner. Carpet would work great. The cost of fittings for each tank is minimal (under $50), so it makes sense to have several large tanks. Putting everything into one tank is asking for an accident, like a frozen pipe, that can lose your entire water supply. Also, have several tanks makes it easier to isolate one to clean.
 
Destiny Hagest
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I'm definitely a fan of round designs to distribute the pressure from the surrounding earth. Carpet is a great idea, might also help to insulate the tanks. After reading the Oasis book, it looks like we'll definitely be going the radical plumbing route, so we can spare a few bucks for extra fittings on multiple tanks. Not looking forward to how far down we're going to have to go to avoid the frost line, and this is rock country too.

I'm wondering if it would be efficient/feasible to surround the tanks with an additional thermal mass to help insulate them some more?
 
Jennifer Wadsworth
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Are you planning an attached sun house/greenhouse for your place? if so, an emergency supply of water can go in there. I know geoff lawton talks about a place in Wisconsin that did this. Also - I can't remember, does Ben Falk do this?
 
Destiny Hagest
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Yea ideally we're going to go with the Oehler design, with the uphill facing patio/greenhouse design.
 
William Bronson
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"Round is sound"
I wasn't sure thus would matter much if the tank was basically an in ground pool. Not much chance of the sides collapsing, at least not outwards.
 
Abe Connally
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William Bronson wrote: "Round is sound"
I wasn't sure thus would matter much if the tank was basically an in ground pool. Not much chance of the sides collapsing, at least not outwards.


if it's completely buried, then the earth will contain the forces, BUT, the difference between a cistern and a pool is that a cistern is emptied and may sit empty for some time. This can cause the walls to collapse, and I've seen that happen more than once with buried cisterns. So, just be careful with it, and if it's buried, make sure it's
 
Ernest Smith
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How about reinforced masonry?

It can be built (almost) as strong as reinforced concrete, lined with various things. To those not familiar it uses concrete masonry units (CMU, aka "cinder blocks") with some dividers knocked out. You put rebar in there and grout it in place. I don't know why you could not do the grout one wheelbarrow at a time. It should be vibrated in place ideally, but if you just do a few layers of block at a time, it should work with agitation by hand.

Structurally, the grout (concrete made with pea gravel) just holds the rebar in place and provides compressive strength. The rebar provides tensile strength. In other words, it isn't really about providing a waterproof wall like with a regular concrete tank. Hence the need for a liner.

Perhaps asphalt would work, but I would tend to go straight for thick plastic myself.

. . .

P.S. I forgot about "post tensioned prestressed" . . . things. It's how grain silos are built. Sort of - I'm mangling the terminology. They have concrete blocks that fit together and tensioning cables that are wrapped around to hold it together when filled. "Post tensioned" means that the cables (or rods) are tightened after casting (or assembly). "Prestressed" means they are tightened before the load. It's a term that comes from concrete construction.

I'm an engineer, and have been extensively trained on these things, but I do something else in practice. When the rubber meets the road, so to speak, practical considerations are paramount. (Engineers and builders are a team that have to work together.) I don't do structural work, so am not of much help on the building end. The people who trained me designed natural gas tanks from concrete (big ones), so they can even be made gas-tight at high pressure.

I'm a fan of concrete-type materials because of the long lifespan. Steel theoretically lasts forever, but you absolutely positively have to keep corrosion at bay. I like the idea of a CMU silo-esque tank with post tensioning cables/rods around the outside. No embedded rebar required. You can see them and keep them "healthy," even replace them as required. Just use #3 or #4 bar, thread it, and screw it together.
 
Jim Bryant
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This design seems to be cheap to build. Do you think that it should have a liner on the inside? If not, won't the metal leach into the water?

http://www.backwoodshome.com/build-a-cistern-out-of-corrugated-road-culvert/

Thank you
 
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