BEFORE YOU INSTALL Water pressure check, dimensional drawing. Checking your water supply The lowest working water pressure is 20.3 PSI, the highest water pressure is 108 PSI. If these conditions cannot be met, the bidet may not function as intended; the flush and bidet functions may not work properly. Confirm dimensions of product with installation space Wall Unit: inches 15.66 i T 26.92in n z apg] Side profile Front view Top view BidetMate.