I will give you more than you asked for which will help you from now on. Never diaginois part of a problem then ask someone to furnish the other part unless you are certain about the terms you are useing. In this case,just tell us what you see and hear. Does it sound like uncle Ramos passing gas following Thanksgiving Dinner or like a gut shot bear pleading for relief? "Water hammer" sounds like,,,,,,, well,like someone hit the pipe with a hammer when facuet is quickly closed. You said "It only happens when all the way on, no difference whether hot or cold water." That sounds to me like the facuet makes a noise while running fully open. That's not water hammer,that is somthing (likly a washer) loose in facuet viberating and making a growling noise.

If indeed you have hammer,you need to locate and recharge the chamber per instructions printed on it.

As klem1 said, water hammer happens from a sudden stoppage of rushing water (or air). In understandable terms, if you have your valve wide-open and have water travelling through your pipe at 100mph, then rapidly close that valve, the water in that line goes from 100mph to 0mph in an instant. When that happens, the energy/force from that rushing water suddenly being blocked has to go somewhere. If you have fixtures and/or pipes that aren't securely fastened to a stud or block, the fixture/pipe shakes and strikes something solid. That's the banging sound. The banging should only last a second or two because, by then, the water has stopped and there's no sudden energy transfer. (Even with loose fixtures/pipes, if you close the valve gradually, you won't get water hammer.)

Are you on a pump? If it's banging while the water is on, you could be getting surges from the pump that could move inadequately strapped pipe.

Generally, air in the pipe only will make a fixture "spit." I guess if it's forceful enough and your fixture is really loose, it could create a minor and momentary movement, but unlikely. And once the air is bled out of the system, it should be smooth sailing.

Only other thing I can think of, based on current information, is that you may have a break somewhere that's causing the pipe to gulp air at irregular volumes or leak water at an irregular rate that's causing the flow rate to change in that faucet line and, in essence, creating surges. Seems unlikely.

J

Hmmm....confusing.

The sound is like the pipes are being banged furiously with a hammer. It's only when water is running and only at full force. It's not causing spitting which did happen when we first turned the main back on. In the past it would spit and make a few loud bangs at each faucet as we turned them on but after that no problems - this is the first time for this lingering situation.

It doesn't happen for a second or two then stop, rather it keeps going as long as the faucet is fully open.

We're not on a pump.

I wonder if I should try shutting the water (main) off again and turning it back on with all the faucets open to see if there is some air that would get forced out. Although from the previous comment it doesn't sound like you think it's air. If I did want to do that can you please tell me: do I open all the faucets before turning the water off, turn it off, then leave all faucets open when turning it back on?

Unless there's something unusual going on, it shouldn't matter if you open one, more than one, or all before you open your main. An air pocket isn't going to move in reverse, at least not horizontally, against a wall of water pushing behind it.

Try it first by opening all outlets, then the main. All air in the system will be purged. If it's still banging, there's something afoot, but I can't think of anything else...for the moment.

J

I'd get a professional-we had to replace our pressure regulator last time our pipes were making noise. I'd hate to think what might have happened if we kept on trying to just turn on all faucets to mitigate the problem.

Thanks for all the comments!

Another thought...falls under the realm of unlikely possibilities, but who knows.

Do you have a water hammer arrestor for that line? Maybe there's a hole/break in the arrestor that's making it gasp in air, then exhale, and doing that repeatedly and causing the dynamic pressure in that line to fluctuate from air bleeding into the water flow and causing some movement, like a cavitation.

Just thinking out loud.

J

Another thought...part deux.

Do you have a pressure regulator between the water service line and your house?

The regulator should be passing a steady stream of water at whatever psi it's set at. If somehow it's malfunctioning and sending pulses of water at varying rates, it could be akin to a constant on-off-on-off type action.

Or, you just could have a bad fixture with a bad washer or stem that somehow causes some vibration/pulsing.

***Please read the paragraph below before this procedure: If it does it only when it's running, try this. Close the angle stop for your cold line and disconnect the supply line at the fixture-end. Get a big bucket. Open up the angle stop and run water into the bucket. Do you still get that noise? If not, repeat with hot line.

Caveat emptor: If you have an old angle stop, be it gate or ball, and it hasn't been touched in years, even decades, it may not close or re-open. Even if it works, it may continue to bleed from the stem of the handle. If that happens, you will need a new angle stop. BE AWARE of this possibility. I don't want to be the one who created another problem, so you have been FOREWARNED.

J

Got it - thanks.

I'm not plumbing-capable so I'm thinking this might be better off in the hands of a plumber. I'll post back later to say what it ended up being in case you're interested.

Hi Leslie,

I have a similar problem. Did you come with a solution?

To explain, I have been developing my basement and put new water lines using Sharkbite. After the last step when I directed and installed all the lines to the location of planned sink, shower, and vanity, I hear noise anytime turn on the water on the main floor. Before closing the ceiling with drywall I need to know if I have to do something about it.

comment are appreciated!

Here's what we did but I don't know if it's at all helpful in your situation. The banging was only at one sink - the kitchen - and only when turned the faucet on full force. Our solution was we just didn't turn it on full force, haha. That was the short-term solution.

Then we had a plumber come in for something else and asked about that kitchen faucet banging and he said that the only solution is to open up the third floor shower plumbing and put in two aerators to help the air escape from the line. But we didn't do that.

Instead, the next time we left home for 2 weeks we tried turning off the main and turning it back on in the order he recommended which was: He said in the summertime if you want to shut the water off to the house, just shut off the water main in the basement. There is no need to open up the faucets at that time. When you return, open up the third floor sink and shower faucets, and then turn on the water main slowly until the water is running out of the third-floor faucets at full speed. He said in the wintertime you can do the same process as long as you leave the heater on in the house you shouldn't have to worry about pipes freezing.

So either shutting the main off and back on with faucets open on the third floor helped solve that kitchen faucet problem or it somehow resolved itself and that was a coincidence. Either way, it no longer makes the banging noise.

I don't know that that will help you but good luck!

Leslie,I'm glad you didn't let the plumber open any floors because imo your plumber is at best a joker, maybe even a greedy bum. While it's true that following a certain routine while turning water back on can prevent air in lines,air in lines can cause brief spitting at facuets but not hammer. Techinaly,air in lines might even prevent or miniumize hammer.

Thank you Leslie and Klem