This is the second water cistern I have built with a similar technique that I thought up in order to save money, use scrap material, and last as long as possible with the most minor investment.
This first picture shows the lid and vents on my original cistern. It's 16x6x5 which allows for about 3600 gallons of water storage. The large vent prevents condensation from building up. With plenty of airflow, you won't have mold or anything funky growing in your cistern. I shared this picture because I have not built the lid for the new cistern yet. This gives you a better idea of what a complete cistern looks like. The first cistern is located next to my shop to store rainwater from its roof.
I dug both cisterns by hand but I had a friend help me with the first couple of feet of the second cistern. I do everything I can to be as frugal as possible with an end result that will work well for several years while I expand my homestead. I came out here with very little and by the time I need to upgrade this system, I will be able to afford to do so.
This image is from the first cistern. I'm sharing it for two reasons. Firstly you can see the simple vinyl liner I laid down to line the inside of the hole I dug. Second, you can see I did not use a liner between the timber and the cistern. I wound up spraying enamel cistern paint on the timber which will be fine but in the second cistern, I put down a liner so I don't have to go back and paint. It will just work better this way.
In the new cistern, I laid a vinyl liner inside the hole. It's the white liner in this image. Then I laid a brown liner to cover the hole and used timber to pin it in place while I worked it around the perimeter.
Once pinned the second liner down, I filled in all the gaps so the entire top of the cistern is covered in timber except for a manhole like the one in the first picture I shared. This way I can climb down into the cistern to clean it out if or make repairs if I ever have to. Now I simply have to carefully cut a hole in the liner and fold the lower liner up into the manhole and the upper tarp down into the manhole. This way the entire cistern is encapsulated in the vinyl liner. These liners should last 10 years being buried under dirt. Any overflow can flow into the swale you can see in the bottom left of the picture. The swales lead around my property to my pond and out to my orchard.
I was able to order enough billboard liners to line both cisterns and my pond all of which will hold at least 3600 gallons each for under $200. That's about 11,000 gallons of rainwater storage for under $200. I know rich people might not understand my method but this is a perfectly acceptable way to get a great head start on a system like mine. When building a homestead on a budget, sometimes it just makes sense to spend very little money for a pretty great result. During monsoon season both my original cistern and pond filled up overnight! It's amazing what you can do with a little forethought.
Here's a video that might give you a better understanding of this build.
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