The water in my bath tub is not coming out. There is pressure when the faucet valve cartridge is removed but when it is put on the water hardly comes out. This is a new valve cartridge and the faucet has been replaced numerous times with each plumber. Everything has constantly been replaced and it is getting costly. We were getting a little sand in our water and a light rust residue. The pipes in the wall were replaced a couple years ago with new copper pipes, but the bathtub water keeps doing the same every few months. Any answers? Please help me!