[pvaldes]

You either had clay in the soil, or need to add a thick layer of clay for that. Then you use machines to compact the clay layer, remove air and made it watertight. Put water, will turn into a brown mess, wait for the clay sinking eventually, done.

If you don't have clay, ducks can provide manure that turns into fine mud with the same properties and pigs can provide the compact work, but will taint the water later with nitrogen. Machines are better.