Posted: 7/8/2007 11:28:18 AM EDT
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I'm going to put some large cisterns in this coming spring... I'm thinking about prefab concrete tanks, but thinking I might instead make my own. I've seen ones where folks somehow plaster a chickenwire lined hole, etc. Open for ideas. My current plan is probably not the cheapest, but I was going to dig my hole, form up concrete walls using 2x8 and the USP 2x form ties, and do 2 5' high pours for a 10' high wall. #5 rebar 18" on center in a mesh on the walls. Followed by a poured top, 12" thick, #5 rebar on a 6" grid, with two manhole access covers. I believe the poured tanks will be cheaper; My number one reason (besides it's good to have lots of spare water!) is putting in a standpipe for the fire department or myself should we have a wildfire. I'd like to have a minimum of 4000 gallons available without having to pump from one small tank to another. Ideas/Thoughts/Experiences? ETA: I'm going to try to fill these with rain runoff from my barn, and then top off if needed. If I can build several, I'd irrigate too, but I want to cover the fire protection base first. |
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Guy next door went with a few (new)  septic tanks. He built a sand filter on top and routed all the downspouts into it. These came off of the house, 3 car garage and a 40X60' pole barn, so he was collecting water from a pretty large surface area. They have no well and use it for household water. YMMV |
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Tag for more info . cisterns , first one I ever saw was in Grand Junction CO. Never new of such a thing , water truck came 2 times a month for a 2.5 person house hold . Not sure of the size , I would say 5 foot deep . here |
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I'm no expert, but I did stay in a Holiday Inn Express last night and lived in cistern land in the USVI for many years. Concrete or block cisterns are the most expensive and VERY prone to leakage no matter how well you build and seal them. They are more difficult to clean when the scum builds up and you have to drain them completely every time you pull maintenance. concrete also leaches calcium and other things into the water. If you live in a hurricane prone area, before the storm, disconnect your inlets and seal them well to prevent salt water picked up by the storm to enter your cistern, causing contamination headaches and salt will weaken the cement. Concrete cisterns are usually integral to the homes foundation and constructed as part of the house itself. Down there is was about a $1.50 per gallon to construct. The prefab fiberglass tank cisterns are cheaper and can be located anywhere, above or below ground level. These are easier to maintain and rarely or never crack or leak. A real cheap way to go is the above ground swimming pool. It can also be sunk into the ground and covered. The water has to pass through a primary and secondary water filter to remove all the crap that will grow in them. the water is still contaminated due to bird shit and should be treat further is you would like to use it for drinking. Otherwise it's fine for flushing and showering. Unless treated, it can also become mosquito haven! In all cases, prevent storm contamination by disconnecting inlets and sealing them well. Lots of critters can make their way in as well, contaminating the water. |
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Thanks for all the info! If I find anything else, I'll add it to this thread. Also, when I actually pull the trigger I'll post what and how with pics. This will definitly need to be buried in the ground, and will have a 3" fire department standpipe coming from it. The fire department suggested I use the concrete ones that are sold here. They are manufacturered by the same folks that make septic tanks here and are brought in as one unit. Either way, I want it buried and covered, so it's not obvious. The fiberglass ones here are per gallon, 2x the precast concrete. I was thinking if I poured concrete for the structure, then used an EPDM liner, that might be the best overall. For drinking, this is really a last resort, fire suppression and irrigation are it's main uses, as I am putting a 500g potable tank in the basement. |
| We had a cistern for years at my Grandfathers. He built it under a back room that he added on. It was added on in about 1973. I have no idea what he sealed the blocks with but it has never leaked. It is fed from the gutters on the house. We have used the water for drinking ever since and have had no ill effects. At first is was fed off a tin roof that was God only knows how old and now off of a shingle roof. I believe it holds 10,000 gallons. They have no well and almost never have to get water hauled in. Well as long as they keep the gutters clean. |
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This sounds like a fun project. If you want my two pennies worth of advice read on. I would have a nice footing, say about 18" square with three runs of #4 through it. I would then have #4 and 8" @ center for the floor, and make sure it is chaired. I would also have a 6" thick floor. Now if I went with a wider spacing on the rebar, I would lay chain link fence down, pull it tight, and tie it to the rebar to help with cracking. It all depends on how much money you want to spend, and how you plan on finishing it off. In the walls, all you need is #3 rebar horizontally every 10". There is no real pressure pushing out, and besides, the ground is pushing back. I would rather see you use smaller rebar that is closer together to help keep cracking down. Also, #3 is SO MUCH EASIER to bend around in a small circle like this. If you really want to have a tight mesh, again, wrap it in chain link fence. Wire tie the fence to the rebar. If you do this, make sure you have a vibrator to get the concrete wrapped around the fence. Now for your verticals, I would use the #5 and make sure they come out at the top of the wall. You will need to spice these into your top with at least a 3 foot splice. I also would make one pour if I could. If you make two pours, you have a good chance of a leak at the seam. I would use THIS before the second pour, and across the seam after you take the forms down. That should take care of any leaks at the seam. The top is a little different. To get 4000 gallons, and be 10 feet tall, you are 8'4" wide. Now that is not a big span, but why do you need to be a foot thick? That is going to be very heavy, about 7100 pounds. Now if it was me, this is where I would make two pours. The first would be four inches thick to give me strength, and cover the rebar, which is #5 and 12" on center, and chaired, and then the second pour a couple days later to add the last 8" to give me my 12" thick top. This will greatly reduce your chances of a catastrophic failure in your top pour. If you still want to go 6" @ center with your rebar, I would not make fun of you as you can never have to much rebar. Again, I would use that epoxy sealer or something similar, between the top joint and the wall. After I was done, look at sealing the whole thing with some sort of THOMPSON'S WATER SEALER or something like that. Even a good epoxy based paint would work. I would go to a real paint store and ask them if the epoxy based paint could be used on the inside for potable water and see what they say. Maybe even go to a pool store and ask them how they seal their in ground pools, and if it is safe for potable water. This way, you are sealing the floor, and the walls all at once. |
I think it all depends on what kind of roof you have, and what kind of filtering you have. I'd drink my roof water in most situations - It's an epdm flat roof, easy to clean... Probably full of fire retardants, but I'd run it through my reverse osmosis unit before I drank it. In my original post, I'm interested in building large cisterns for fire suppression and gardening. |
Theoretically, yes. In colorado, water laws are what they are, and keeping a pond full generally requires water rights that cost more than most peoples houses. A covered cistern will minimize evaporation. Theoretically, the water washing across your land is not yours, and the water that hits your roof belongs to someone else too.  I am in a very rural area, and we have a hydrant about ~2000' away, which still means they have to run water tenders. However, they are always very very happy to have an on site cistern to augment their own supplies - They said that when defending a house from advancing fire, don't really spray and pray with the water, they are pretty careful with it (wildland fire suppression) so those gallons go a long way. Right now, I'm probably going to pour 12x12x10 and line it with a liner, to make use of a specific location I have. I forgot what the exact capacity is, but it's into the thousands - From this I'll run a single drypipe that meets the fire department specifications. |
1000 gallons is peanuts and might just fill the lines depending on their length. For firefighting purposes, I wouldn't have any less than 20,000 gallons available....and that would likely not be enough. |
Ah, Ok, and you guys out west complain about NYS? The whole water issue is one reason I wont even think about moving out there. Keeping a pond full around here is nothing more than having a pond near a spring or a pond that retains precipitation. No cost involved other than the cost of digging and maintaining the pond and the supply pipe by the roadside that the FD hooks into. |
Check with your homeowner's insurance co. about this. They may have some suggestions that, if followed, would decrease your insurance costs. My sister put in a pond at her ranch and got some $$$ off her insurance bill. |
I'll risk it. Like I said, we're not that far away from the hydrant, I just want some water close'er to my place... They will be running hose trucks or tenders either way, but by the time it hits the hill behind me, they will be running slurry bombers et al. I hear they have trucks with just super long hoses on them. I don't have any neighbors close (They are all closer to the hydrant than I), so I figure if it's getting used around my house, I probably want them using it. The cistern at 12x12x10 is just about 10k gallons. I want one to catch the barn water, and a second, to be built later, to catch the runoff of the house. Certainly not enough to put out most fires with, but as long as I have power, I can pump from these and run the sprinklers I have around (and on the new barn, on top of) to keep things nice and wet. The reason I've been exploring the home built option is the poly tanks I can get around here max out at about 1500 gallons. The EPDM liners are relativly cheap, and I'd do it without any seams until the overflow outlet. Thanks again folks! h ETA: I'll post pic's when I start construction. I'm relying on the concrete for strength and giving me a "top" that a horse can walk over without err, but not vehicle traffic. My structural engineer gave me a schedule for an unofficial top that doesn't exsist. I've got two manhole covers designed into it, with a rubber liner. The concrete might actually be good enough to hold water long term if I had it plasted the way pools are, but the rubber is cheaper and requires only an evening of labor on my part. |
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Hi, I don't recall posting to this forum before or not, but I read it quite often. I have often thought about the idea of water storage and thought I would share my thoughts and a few ideas on this topic. A couple of years back I had a 25,000 gallon pool built in my yard. Overall the experience was a nightmare but I learned quite a bit on building in ground pools so that the next time I get a pool built I will be better able to deal with the BS from pool companies and contractors. In thinking about it, there is not much fundamental difference between pool construction and building a large in ground cistern. Why not build a Cistern using Gunite and plaster like an in ground pool? Gunite is stronger than concrete and depending on what part of the country you live in, the cistern would be less likely to crack when it settles when filled with water in especially if you live in areas with expansive clays such as the Texas Gulf Coast. As I recall, water weighs 64.4 pounds per cubic Foot, so when water is added any structure built into the ground, it would have to be able to resist cracking due to uneven settling, expansion and contraction due to temperature change or groundwater table elevation. If you line the inside of cistern with plaster then it will fill the voids and make it more water tight. For a smaller cistern, you could use a precast storm manhole for larger pipes. You can order them for many different depths. Dig a deep hole (if you can), set the Manhole into the ground so that the top sits up about 1 foot above the ground, and fill it in. Another type of in ground water storage that would work well for people who don't have far to dig before they reach bedrock material would be to use a series of corrugated steel pipe or corrugated High density polyethylene pipe and connected together in the shape of an "E" with the ends of the pipes plugged and capped and then buried. These can be built anywhere, any size any depth (depending on the pipe size used). They have been using this type of system for several years for storm water detention/retention but could be used for water storage too. I looked for a web page describing the process and found this: This is a diagram of the pipe structure: www.atlantic-csp.com/pages/bespo01.html When I was younger, a friend of mine and I found an old abandoned house out in some woods near where I used to live. The house had a big wooden above ground cistern that was about 5' in Diameter and 7' tall. It was built like a big barrel. The house was built in the late 1800's to early 1900's and the cistern was still water tight and still collecting water (and millions of mosquito larva) up to the year 1985 when the house burned down. The Cistern was built on a platform 5 feet up off the ground and provided water to flush the toilets in the house and had a faucet on it to connect a hose to. The point in this being, a well built cistern should last a long time. Just some ideas I thought of. -badlnb |