Bill, I am stopping the spray foam well above the water line. Once the spray foam is setup and curing the rest of the way I am going to stand it back in place and fill the tank with water unto the max level it will be allowed to go and let it sit for 48 hours to test for leaks. If there is a leak the only part that will need to be fixed is the bottom 7 inches of the tank. I had considered doing the water test first, but ultimately decided that the foam will be out of the way and will allow me to let the foam cure and test for a water leak at the same time.

I agree though that water testing is a vital part to the build and would be disastrous if the false bottom and soil were in place and then a leak was found. I will be filling it with water tonight or tomorrow...depending on how firm the foam gets before bed time tonight, don't want the foam to run down the wall