Old concrete rainwater cistern
We have a 100 year old, midwestern residential underground concrete rainwater cistern. It is located six feet from the house foundation. It is eight feet wide by ten feet deep.
We do not want to reuse it now, but would like to empty the water from it, cover it and keep it for possible future use.
Question – Do you feel it could rise (empty) due to ground saturation — or do we need to keep it full of water? We would prefer it empty.
What’s your location.
Frost depth for footings “might” not be a guide as to whether or not it would rise…
Here in NW Ohio I have seen a septic tank rise up quite a bit during a serious rain. That’s why they fill them shortly after sticking them in the ground. They are not as big as your tank I don’t think.
Well drained soils might make it less likely to rise.
Sorry, I’m not a hundred nor have I lived with a cistern.
Appreciate your comments, Calvin. 30-36" frost depth (Northwest Missouri).
We drained it but may end up refilling it, returning it to the original way we found it. Thought it would be less of an insect & rodent draw if it was dry, but probably not worth the risk.
Hopefully someone with a more educated or experienced opinion will give you reply.
I’m just guessing as a result of showing up to a job next door to that recent tank install. Around here at the Ohio Michigan border we have a sizable layer of near impenetrable clay. It was called the Great Black Swamp.
Was it full of insects and rodents?
You might want to consider adding some screening or sealant to prevent access by them.
Another option is a chemical treatment. (similar to pools) should not require huge amounts of chemicals, since it will not be exposed to sunshine and the surface area is not completely open to the great outdoors.
I agree with your assessment that it likely is best not to try to leave it empty.
Swimming pools float, that’s why they have hydrostatic relief valves. You might look into a retrofit.