Hello All,
First of all, I apologize for the length but im trying to give you all everything I can think of. Ive read a lot of posts about this issue that have helped me narrow down the water hammer sound and actually eliminate it, the catch is to eliminate the "hammer" I have to stop the flow to each shower fixture. Im pretty sure this means I need to replace both fixtures/mixing valve systems and the hammer will be eliminated and I can use the showers.

The house is 11 years old with 3/4" and 1/2" copper lines and there was no hammer sound for 7 years. No fixtures have been repaired or changed. I am on city water with a pressure reducing valve. I have been throughout the house checking for loose pipes or missing plastic buffers and have found nothing missing or loose enough to bang against studs etc. to make the noise. I have checked the pressure on the main line with no valves open and I have checked the pressure with valves open, in both cases it was between 44 to 48 psi. I have drained all the hot and cold water from the system and turned it back on to force any air out of the lines, which seems to lessen the hammer for awhile but not long.

When I started to slueth this problem out, the hammer was always at the boys shower/tub no matter what source of water was used or if it was cold or hot. In other words, the washer, dishwasher, kithcen sink, both (2) toilets, both showers (boys and master), and both bathroom sinks (boys and master) would cause the hammer sound at the boys shower/tub. One fixture is a shower only, one is a shower/tub fixture, and both are 1-handle systems made by either Pegasus or Glacier Bay (I know, not good).

So last night I read on this site about some water stops on some mixing valves that can go bad and I thought maybe I have these and maybe this is the problem. So I take off the handle etc. to access the guts and sure enough the mixing valve does have these stops and I proceeded to screw them shut to stop water flow to the shower cartridge. Then I flushed the toilet and voila there was no hammer. Then I went to the boys sink and tried the cold water...no hammer, then the hot water...no hammer at boys shower but a hammer at master shower, crap!! Then I checked all other sources, and it hammered at master shower only when source requires hot water. So, I go to the master shower and turn the water stops off and voila there is no hammer from any source, cold or hot. So, all stops shut on both mixing valves equals no hammer at all; all stops open equals hammer at boys shower from all sources, hot and cold; stops shut on boys shower only equals hammer at master shower with hot water sources; stops shut on master shower only equals hammer at boys shower, hot and cold.

I guess my questions is: 1) Am I right to just replace the whole valve and fixture?

Replace the pressure balancing spool if there is a separate one on the valves or the entire cartridge if it integral with the cartridge.

you can probably get free parts from which ever of the big box stores that sell those brands.
if they won't help they can at least get you in touch with the manufacturer's rep..

Good luck getting the "correct" part you want from either of those companies, (which are probably the same one anyway). The customer "service representatives" usually send you what THEY think you need, not necessarily what you asked for.

Before "replacing parts," you can try this. Works for some (& has, for me).

Turn off the water at street or main valve at house (if it fully stops flow).
Close the valve on your water heater.
Open water valves in house. Make sure in each area of house, the valves lowest to ground (and / or slab) are opened - to drain. Even if that's outside faucets.

After the bulk of water's drained, close the shut off (stop) valves on the toilets.
Rest of valves that you opened, can now close (if want).

Turn water back on at main valve.
Last of all, turn toilet valves back on.

Many (most?) houses have a vertical section of pipe above the toilet supply valves, to hold air as a cushion to prevent water hammer. If some / most of that space designed to hold air gets water, it no longer functions.

I've had to do this on several houses. Several times on this house. Often, after city turns water off, then back on.

Thanks for reply. I looked for the cartridge at plumbing stores in town and no luck. Part number takes me to Chinese company and website. Thought it was best to go better quality.

Thanks again. I will try the water drain trick with the added toilet element. I love easy fixes but Im guessing it will still hammer because sinks etc. make it hammer as well.



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Hello, were you able to fix your water hammer issue? I have the same problem and I've been told that it's due to having different size of plumbing lines. Plumber wants $$$$ to fix the problem. He says he needs to replace pipes under the house.

Please let me know if you found a solution.

Thank you



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Dear phishman, I have the solution to your problem!! And it won't cost you a penny. I am a maintenance man at a condo in south Florida and one of the unit owners mentioned to me one day that he had some water hammer and wanted me to take a look. When his master toilet and/or cold water valve on his master sink was turned off the water hammer was bad, i mean really bad, it would hammer 4 or 5 times. We put one of those hammer arrestors at the toilet valve and I actually think it made it worse! After cutting numerous holes in the walls, hoping to find a loose pipe somewhere and finding nothing I started looking online. Then thank God I found your post! He has a Glacier Bay shower valve too that's about 4 years old. So I screwed in those adjusting screws you mentioned too and like you, no more water hammer at the sink and toilet but no water at all at the shower either!! So long story short, those adjusting screws screw into a sort of nut or base that has a hex head. First , don't forget to shut your main water valve and bleed off the pressure. I like to flush a toilet to bleed off the pressure. It takes a fairly big socket maybe 5/8 or 3/4" and you will need a deep socket but carefully remove both of them (hot & cold). Along with being an adjusting screw, they are also a check valve. Be ever so careful cuz when you remove that nut and screw assy. from the mixer valve, it's easy to drop it in the wall and then you're finished!! I don't know any easy way to get it out of the wall. You may want to pack a washcloth in that hole to be sure that doesn't happen. Anyway, once you have both adjusting screw/nut assemblies out, grab the adjusting screw with one hand and twist and pull at the other end which is round and has a rubber seat in it . Be careful because when that thing comes out it has a stem that is about 1/4" in diameter and about 3/8" long and there is a spring inside and you can easily lose it. So that little brass part with the rubber seat in it is basically a check valve and it must float freely. Both of the ones I was working on had corrosion on them but the one for the hot water was worse and was actually kinda stuck. I cleaned up the corrosion on the little stem with some fine sandpaper and put some lube on the stem/spring, and reinstalled them, no more water hammer!!!! I'm not sure I ever would have found it if it wasn't for your post so I felt obligated to return the favor. Good luck and thanks again from South Florida!



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Dear Anna Galvan, I believe your plumber is not being truthful to you. I am not a plumber, I am just a maintenance man but I have seen and repaired a lot of plumbing in homes and typically the pipe is larger diameter for example 3/4" at the main valve and the water heater and as it branches off and gets to it's furthest point such as sinks, toilets, and showers it will reduce to 1/2" in diameter. I'm sure that California has strict building codes and they would never have allowed different sized pipe if it wasn't ok. If your house never had water hammer and now it does, you may have the same problem that I had. I posted a full reply to phishman but I will give you a summary. If you have one of those one handle shower valves that when you rotate it slightly, the water comes on cold and the further you rotate it, the hotter the water gets, then if you are handy, remove the handle and the cover so that you can now see the valve itself. You will see the large stem/cartridge in the center and two adjusting screws on either side of the stem/cartridge. take a screwdriver and turn the adjusting screws to the right until they stop, just snug, don't over tighten. With those screws turned in you will have no water at that shower but now try your sinks and toilet and whatever else was causing water hammer. If your water hammer is cured then chances are the little check valves in those adjusting screw assemblies have some corrosion on them and are not able to operate smoothly, causing the water hammer and they just need to be cleaned, not replaced. If you have two or more showers with that same type valve, try the same test with all of them one at a time, leaving the first one(s) with the adjusting screws turned in. If one of them stops your water hammer, I would still clean all of them, otherwise you will probably be taking the others apart shortly to clean them too. To clean them refer to my reply to phishman. And if you are going to clean them yourself, don't forget to shut off your main water valve and bleed off the pressure. I like to flush a toilet to bleed the pressure cuz it will continue to drain and you don't have to concern yourself with shutting it off once you turn the main water valve back on. Good Luck!!



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