So a week or so ago we had a water main break in our street, leaving us without water for half the day. Once it was repaired, we have had what some call “water hammer”, others “pipe shudder”. Every time a faucet gets shut off, there is a one or two second vibration in the pipes (applies to all water sources in the house - showers, toilets, outside hoses, etc.). Its clear that there is a pocket of air in the lines somewhere, but what can I do to get rid of it? I’ve tried running all the water at once, only the highest line in the house, I’m pretty much out of ideas. Any help? Or should I just suck it up and call a plumber?
Well,how handy are you?
It sounds to me like your city water pressure is now too high.If you live in a Condo or Townhouse you can have the pressure regulator adjusted.
You can also install a dampening device that will absorb the shockwave of “Fluid hammer”.That would involve a bit of pipe “sweating” work.How are you with a torch?
Try calling the water company. Ask them what to do Im sure they would be more than happy to come & correct it themselves or tell you what to do. We get a lot of that here & the water then comes out brownish & they told me what to do about that. But you don’t have brown water 
I agree with both handy and RichG7subs but since I just installed a pressure reducer and there is a chance that your water pressure is too high (Hypothesis: your plumbing is susceptible to water hammer effects and pipe shudder but it wasn’t noticable before the city raised your water main pressure when they fixed the break) I’ll mention my experience with that.
My house was built in the 1960s when pressure reducers weren’t used and when you were lucky to have ENOUGH water pressure. A few years ago the county installed a new water main. I didn’t notice any difference. A few months ago I had a new toilet installed that makes noise filling for a few seconds every few hours, day and night but I couldn’t detect any leaking. The plumber checked my water pressure and said that it is too high (around 160 psi) and that it was causing the toilet valve to open to relieve the pressure every now and then. He said I should get a pressure control valve which he would install for only $270 even though he would probably have to do the work in the crawlspace. The pressure control valve limits pressure to around 55 psi. I tried to find out whether pressure contol valves were worthwhile or a scam but didn’t find any good information. However, my water heater is rated at around 150 psi suggesting that if my pressure from the street really is 160 psi, I should probably reduce it. I have also noticed that my water heater pressure relief valve drains a little bit from time which it shouldn’t do. More persuasive is an experience I had a few months ago with an inline filter for my refrigerator ice/cold water dispenser. I had installed a new filter near where the supply line ties into the cold water pipe in the crawlspace and about a week later discovered my basement filling with muddy water. One of the filter’s O-rings had blown out. I replaced the filter with another brand and have had no problem since but it did convince me that having more pressure in your pipes than you need is not a good idea. So last weekend I paid $30 for a 3/4" pressure reducing valve (deluxe model) at a hardware store and installed it. It was a very simple installation (except for the fact that it was in the crawlspace). The only difference I notice is that I have had to open some faucet supply valves that I had partially closed to limit the force of water coming out of the faucets. The toilet still fills for a few moments every few hours (it must have a leak after all) but it is much quieter.
So, if the mains pressure on your street is high and you don’t have a pressure reducing valve and the water company has no other suggestions, you might want to install a pressure controller on the theory that your problems are caused by excessive pressure.
Well thanks for the advice here. I hadn’t even considered a change in pressure as a possible cause. I think I have a prssure gauge somewhere around from when I installed my sprinkler system. I’ll check that first. I’ll also call my water co. and see what they say.
Thanks again.
Might be a simpler fix. Turn on every tap in the house (and remember the ones on the washing machine) and let the water run for a bit. Then go to the lowest taps in the house (basement bathroom?). If there’s a toilet there too, flush it, and turn off the taps. If you do that in strict order from lowest to highest, you may be able to get the air out of the system. Also, turn your taps off gently, don’t hammer them off.
I got that advice from a retired plumber who lives next door. It worked in my house.
I think he tried the all water faucet thingy…
At any rate, Im pretty sure there are special little gizmos you can attach to your hot water heater that let air out. I forgot what they are called.
Air in the lines is definitely not the problem. In fact, a little air in the system could actually be the solution!
Yes, excess pressure can be a factor in water hammer, but only insofar as it increases the velocity of the water traveling through the pipe. The real cause for the destructive transient wave phenomenon that people call water hammer is overquick closing of a valve or valves, creating a rapid deceleration of the water at the valve point. During the deceleration (valve closure), the water is compressed to some degree at the valve by its own kinetic energy; the pressure ‘kicks back’ up the line in a wave, ‘pulling’ at the water at the valve and creating a lower pressure there; the wave meets and compresses water in the pipe upstream from the valve and a return wave is generated; when the return wave hits the valve, the whole cycle is repeated until the system stabilizes. In household plumbing, this is generally a matter of a few seconds or less, and the annoying sound you hear is actually the pipes moving, knocking against the framing of the house.
In the modern home, water hammer is most often associated with washing machines, which feature flow control valves operated by electric solenoids that tend to close very quickly. If the service pressure is way too high (over, say, 60 psi), the problem is often exacerbated – again due to increased flow/velocity – and water hammer can occur at other points where valves are closed.
The most common control device I’ve seen is just a few bits of pipe tied into the water lines – usually, as I’ve said, the ones that feed a laundry area – that are designed to trap and hold air permanently. If the feed line is vertical, the fix is a tee in the line, a few inches of horizontal pipe, then an elbow to turn to the vertcal (upward), then a couple feet of pipe topped with a cap. The result looks kinda like the arm of a cartoon cactus. If the feed line is horizontal, the fix is even simpler, just a tee in each line and the couple feet of pipe and cap sticking straight up.
Once the devices are installed and the pressure is restored, they’ll remain full of air indefinitely. Air is much more compressible than water, and the trapped air will act as a cushion to absorb the transients and eliminate the water hammer. The more severe the water hammer, the longer the vertical length of pipe should be.
I’ve installed a great many of these devices over the years, and they really do work.