A couple of years ago, I started constructing a ferro-cement tank for water storage in the shed/garage near our current home. I planned the tank to hold about 5,000 gallons, collecting water off of the roof of the building. The idea was to run a water line down the hill to the new house from this cistern. The drop in elevation between the cistern and the house would provide about 25 pounds of water pressure. We also wanted to have a cistern for collecting water off of the roof of the new house at some point.
The ferro-cement tank is only partially constructed, and time to devote to its construction hasn’t been readily available. In order to facilitate an earlier move into the new house, we decided to go ahead and put in a cistern near it. I considered options for water storage, including buying a poly tank (or more than one), building a ferro-cement tank, etc. We finally decided that buying some concrete septic tanks would not be much more expensive than building a ferr0-cement tank and about half the price of a poly tank or any other commonly available water storage tank. It also would involve a lot less time than building a cistern.
I hired a guy to dig into the hill in front of the house to create a place to set three 1,500 gallon septic tanks. 
This week, after getting the insulation taken care of, I leveled out the bottom of the excavation site in order to get it ready for the tanks. I hauled in 6 tons of rock to put in the bottom for the tanks to sit on. The intention is for them to have a solid base that won’t settle and cause any of them to crack and end up leaking.
After getting the site prepared on the fourth day of the week, I called to schedule delivery of the tanks yesterday morning. We got all three tanks set in place yesterday (and then baled the second cutting of hay).
The plan now is to drill a 2” hole near the bottom of each tank in order to plumb them all together with shut-off valves for each tank. Also, the water line from the tanks into the house will come from this location. I’ll use one of the existing outlets for an overflow when the tanks are full. I’ll also construct some type of filtration system for the incoming water, which will be harvested off of the roof.
One other task I’d like to complete with the tanks is to coat the inside of them to ensure they won’t leak (they aren’t supposed to, anyway) and to prevent the water from taking on the smell and taste of concrete. I’ll be completing these tasks along with many others during the next couple of weeks.
10 comments:
Please post about the filtration system from the roof. I have two 1500 gallon upright poly tanks and was thinking of a first flush system. I can use the water now for the animals and gardens but in the end I want to be able to run it through another filter system before pumped in the house.
Thanks,
MDR
MDR, I will post about it as it comes together. My plan at the current time for the water entering the cistern is roof washers on each downspout (divert the first several gallons of runoff away from the cistern, washing dirt and bird droppings off the roof and away) and a general filter consisting of mesh, sand, gravel, and maybe charcoal. This will provide water for washing and bathing. Drinking and cooking water will be put through a ceramic filter.
Thanks db. I want to see how all the elements come together.
How does the roof washers know when it is time to divert back to the cistern? Would a sand/charcoal filter be to slow in a heavy downpour causing a overflow and you end up loosing water?
You guys are amazing! I love seeing how you do all of this. :)
The roof washers will likely be built out of 4" PVC so that the first 10 gallons or so from each downspout is diverted. The first bit of rain is then used to wash the roof. As far as the other filter, I don't know yet. I'm thinking of situating it over one of the access holes on top of one of the tanks which is about 18" in diameter. I may decide that sand and charcoal aren't really necessary, just some gravel and fabric to filter out leaves, sticks, small rodents, and things like that. Theoretically, once the roof is washed with the first bit of rain, there shouldn't be a lot of mess getting into the cistern. It will be cleaner than the pond or creek water, and the Burkey filter (ceramic) will filter out 99.9% of non-chemical bad stuff.
thanks for the response, I look forward in seeing it come together.
I really would advise you not to coat the insides of those tanks. You are more likely to have problems from the coating than from the concrete, which is only limestone at the end of the day. We make wine in concrete tanks. You could coat them with tartaric acid (paint it on, leave a day or two, then rinse - no scratching, though) if you insisted, but, "Why?".
Thanks for the advice about not coating the insides. After a bit of research and thought, I decided that coating them would not be a good idea, too. I have cleaned out the insides as well as I could and am happy with them as is.
Yeah, it's best to not coat them. It's like how they're made to resist leaks; those tanks should keep the water nice and clean for ya as they are. It would be less work for you, giving you more time to set everything else up.
I know you have long since the original post completed the water system- so how are you pleased with the system ? also, where di dyou purchase the tanks ?
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