Here's the scenario: Replaced my old well tank (just the standard old galvanized tank) with a new bladder tank. The old tank was in the well pit which wasn't going to be a convenient installation for the new tank. So, I installed the new tank in the basement. The existing 3/4" supply from the old tank was re-routed from the tank and now comes directly off of the discharge side of the pump. The 3/4" line runs approximately 10' into the house where I installed a tee to feed into the bladder tank, a tee to install the relocated pressure switch, and one for a pressure gauge. The problem I have is that every time the pump shuts off, the pipes hammer. I replaced the swing check on the well pipe on the suction side of the pump with an "in-line" check valve thinking that would help since the spring would close the valve rather than relying on water pressure to close it. No such luck, it still hammers when the pump shuts off. This is an older, 1 1/4" galvanized, shallow well and the check valve is located about 2' from the suction side of the pump. This is a 1/2 horse with an 1 1/4" inlet on the suction side and 3/4" outlet on the discharge side. Cut in pressure is 30 psi and cut-out is 50 psi. Tank came pre-charged at 28psi (although I didn't check the charge before installing the tank). What am I missing here? Nothing else in the house causes the hammer. Not even the solenoid valves on the washing machine when they close. Have I plumbed something in wrong? Never had this problem with the old tank, and I would have thought that the bladder tank would act as a shock absorber to prevent this sort of thing. But, then again, I'm just an electrician, so this plumbing stuff is about as easy for me to understand as Chinese arithmetic. Any help or suggestions would be greatly appreciated.