Very Quick Water Pressure Question

I have a bad water hammer issue throughout the house. I have read if it affects multiple appliances, the origin is most likely that the water pressure is too high. Is it possible to reduce the water pressure by partially shutting off the supply line or do I have to install a water pressure regulator?

Thank you

You need a PRV and an expansion tank. Restricting the flow won't reduce the pressure and could induce turbulance, extra wear, and noises. When there's no flow, it doesn't matter whether the pipe is a foot in diameter or 1/8", the pressure is the same. Now, restricted flow might slow it down, and soften the water hammer. Water hammer ONLY occurs when a fast acting valve shuts OFF. If you have noises WHILE the water is running, it is not water hammer. Now, a loose washer on a faucet or other valve can vibrate and quickly turn the water on/off and could be water hammer, but you'd probably notice the flow wasn't consistent. The fix for that is replace the washer or replace the valve - there a lots of valves that no longer have washers in them. If the hammer only occurs in one place, it might just be that the pipe needs to be anchored properly.

I'd first check what the static and maximum pressure is, though. A PRV is typically only needed if the pressure exceeds 80psi, although some people like it lower, and most people's supply is usually lower than that; it depends on how close to the pumping station or water tower you are and your elevation relative to the supply.

Partially closing the supply valve will not reduce static system pressure. it will reduce flow, and the dynamic system pressure drop may reduce the hammer, but you will not be happy with performance. Most important, if you pressure is too high, all the system components will continue to be exposed to that high pressure.

Best bet...buy a $10 guage at the hardware store, and get some idea what your static and dynamic ( in-use) pressure is. If static is over 80, you need a pressure regulator, and should probably also install an expansion tank on the water heater, especially if it is gas.

From Wiki
http://en.wikipedia.org/wiki/Water_hammer

Lower fluid velocities. To keep water hammer low, pipe-sizing charts for some applications recommend flow velocity at or below 5 ft/s (1.5 m/s).

Fit slowly-closing valves. Toilet flush valves are available in a quiet flush type that closes quietly.

A hydropneumatic device similar in principle to a shock absorber called a 'Water Hammer Arrestor' can be installed between the water pipe and the machine which will absorb the shock and stop the banging.

Shorter branch pipe lengths.

Shorter lengths of straight pipe, i.e. add elbows, expansion loops. Water hammer is related to the speed of sound in the fluid, and elbows reduce the influences of pressure waves.

Arranging the larger piping in loops that supply shorter smaller run-out pipe branches. With looped piping, lower velocity flows from both sides of a loop can serve a branch.