Building a Cistern

[dnoyeB]

I decided to build a cistern so I can use the water from my sump pit on my grass. the sump does not produce enough GPM so ill need the reservoir to be able to run the pump without cycling continuously.

It will be 600 to 1000 gallons. Right now it will be 10' long 4' wide and

4' to 5' deep.

I planning to have 8" thick concrete base and the walls will be concrete blocks. My question is, do I need rebar anywhere? and do the walls need to be filled with cement? any rebar in the walls?

Its looking to be 5 blocks high and its going to be in the ground. Any gotchas I should know about? Do I need to have any provisions for drainage around the cistern footer?

Thanks,

Carl

[Pat]

Yes. Yes. Yes. Yes.

Why not use a septic tank. Fast and easy.

[Don Young]

You will need some sort of waterproofing on the inside because blocks and mortar are not themselves watertight. I would definitely use rebar and some cavity filling, as earth pressure can be pretty high and it would be likely to crack when empty. If a high water table is possible you might need some way to keep it from floating out of the ground. There should be government guidelines available, maybe build it like you would a septic tank. Be alert to possible bacteria problems in the water.

Don Young

[aemeijers]

A tight daylight lid to keep down mosquitoes? Why reinvent the wheel? Go to nearest farmer ag supply store, and look at the premade plastic tanks. Leakproof, and likely as cheap as rolling your own, unless you value your time at nothing. Something to keep daylight off it, and it will likely last longer than you will. If you insist on concrete and below ground, call local precast place and see what septic tanks, installed, go for. I've used a new one as a cistern to capture a ground water layer (a spring, really) for non-potable water use. It worked great. 50 feet of corrugated plastic in a gravel layer feeding in, another leading out, and the thing never went dry, and the water was always cold and clear. It probably would have passed lab tests for drinkable, it just was outside of accepted code.

-- aem sends...

[Pete C.]

Well, not septic tank, pump chamber, pretty much the same thing, but without a baffle you don't need. Available from the same precast places and if you have the hole ready and in an accessible location their truck can place it in the hole for you.

[dnoyeB]

I would gladly buy a tank if I could find a store locally. $1000 gallon tanks cost about $600 and delivery is just about as much. I live in Michigan, Detroit, and just can't see to find any such stores around here. Maybe I don't know the right term to search for. I know we have lots of septic systems in my city.

[EXT]

Look just outside the city, for an agricultural supplier. For a septic tank, you go to the manufacturer, "Concrete Products" or such in the yellow pages, look for cast concrete tanks. These things are not transported far due to their weight and need of power equipment to unload them, and not sold through any retailer. Although one would normally be supplied via an septic system installer in most cases.

[dnoyeB]

What if instead of building the cistern next to my house, I trench out the stream at the bottom of the hill about 20' away where the sump water currently goes. I can dig it down perhaps 3' would be safest. And I can streach it wide to make a sort of catchment area. I can easily drop a PVC pipe into that with a filter on it.

I have 2 concerns with this though.

1 How frequently will I have to re-dig it.

1. It flows, but not very strongly until my sump kicks on every 10 minutes. Is this enough to deter mosquities?

What do you think? Sees much easier than the concrete cistern.