We decided to sacrifice the corner in our barn directly beside the big door, so the cistern would be protected from the sun and easily accessible for emptying.
An underground cistern, obviously, is made to go under the ground. This means the cistern gets pressure from outside to withstand the pressure from the inside when it is full. If this pressure on the outside is not there, the cistern could get damaged. So we came up with the following way to build in this cistern above ground.
We started by building a wooden construction coming out of the corner about 20 cm bigger as the cistern is.
This is the cistern we bought.
We put in a thin layer of sand on the bottom to protect the pond liner, which is coming in next, against any sharp spots in the concrete floor.
We have laid out the entire basin with the pond liner, just incase there would be a problem with the cistern, the waist water will be contained and not flood our barn.
This would also have made for a nice pool.
After another layer of sand the cistern is put in place.
Around the sides is also filled with sand which we compacted.
Then we build a deck on top, so we can stand on it to empty our toilet waist in the cistern. The pipe going up is for venting. It has a filter on top, so it won’t smell bad in our barn. The metal pipe is for draining the cistern. The big black lid in the middle is where we can fill in our waist water. The hole in the deck is where we will connect the outlets of the toilet and the shower we are going to build in into our barn this year. Obviously that would not work by gravity, so we will put a waist water shredder pump in between, but that will be a future project.