Violent rattling/banging of toilet intake water pipe when turning on water

The rattling is inside the wall. I had the toilet intake valve closed for more than one year. Toilet is in the basement, and there are 1st floor and 2nd floor in my townhome. To attempt to fix this rattling, I replaced the toilet flush valve, and tried bleeding the water pipes in my entire home as best as I could from my limited online research, but it still happens. It happens when I turn on the faucet to let the water into the toilet beyond a certain threshold. If I keep it open very slightly, no rattling, but if I open it beyond the threshold, the rattling starts. The rattling is isolated to the toilet water intake pipe. All other faucets, showers, sinks don't cause this problem. My feeling is since the rattlings starts when I turn on the water, it's likely to be loose strap holding the pipe inside the wall, but could it be very heavy build up of water pressure since I had the pipe closed for over 1 year? What do you recommend I try to get this resolved by myself if possible?

 

Before I ripped open the wall to see if the pipe is poorly secured, I would try replacing the toilet supply stop valve, especially if it the older type that requires several turns of the knob to fully open or close. Sometimes the washer in them comes loose and can vibrate when the water flows, causing pulsing in the water that can cause a lot of noise.

Replace it with a 1/4 turn ball stop valve. If the old one is soldered on, you may be able to just cut it off and replace with a compression type that doesn't require soldering. You can do this as long as there is enough supply pipe sticking out of the wall.

Since you already replaced the fill valve, if changing the stop valve doesn't solve the problem, you will likely need to open a small hole in the wall to investigate. If there is molding at the base of the wall, you may be able to remove it and cut a small hole behind it to see if you can secure the pipe better.

 

If I do nothing and simply keep the intake water pipe faucet closed, can that damage any water pipes inside my home? The toilet intake pipe sticking out the wall is white. I think it's plastic, or more likely PVC tube. Current stop valve has nuts so I don't think it was soldered on. Will I be able to replace the stop valve without soldering? Please see the pic.

 

Keeping the valve closed is OK.
The shaking is usually caused by restricted flow through a valve, it causes turbulence/cavitation.

Just replacing the valve and keeping it fully open might fix your problem. The easiest way to change the stop would be a sharkbite push-on valve (1/2" nominal inlet x 3/8" compression outlet)

If you use a sharkbite, ensure you have a way to hold the pipe securely while you push the valve on to a depth of ~7/8".

I agree with Carbide, it's probably the angle stop...

 

Hi,
Open the valve all the way. Fill the toilet tank, after the water stops flush the toilet if you still get a water hammer then change the angel stop. Make sure to shut off the water to your unit. It looks like an easy job. I would get a 5/8x3/8 angle stop and a new flex line 7/8 (for toilet) x 3/8. The new flex line will make the job easier. Remove the old angel stop leave the nut on the pipe. Clean off the pipe. I wouldn't use pipe dope on that type of pipe. Install the new valve and flex line. No need for pipe dope.
Good Luck Woodbutcher

 

Town homes often have high psi. I would get a water pressure gauge and put it on the cold water launfrt outlet.

Test pressure with and without water running in the home.

Often PRV valves go faulty and I often replace. As well as faulty expansion tanks.

You may or may not have one but check and see.

PRV should be by the main water line in the home. Exp tank should be close by or at water heater.

 

It looks like water pressure is about 110psi. Is this too high for a townhome? It's 3 stories (basement, 1st floor and 2nd floor), and water pressure gauge is in the basement.

 

In the basement of my townhome (2 stories and a basement), there is the main water pipe assembly like below:

In the guage in the picture, it's pointing to about 110. Is this my townhome water pressure? 110psi? A lof of people have to buy a water pressure guage, but it looks like I have one built in?

If water pressure is 110psi, it looks like below is the water pressure reduction valve? So do I shut off the main water valve > Loosen the nut > turn the screw COUNTERCLOCKWISE to reduce the pressure (Some source say clockwise to reduce to pressure so this is confusing but it will be very important to know which direction I need to turn the screw). Your help is appreciated

 

Yeah. It shouldn't be more then 80. Plus I see you have flow guard gold CPVC piping.

When that piping is installed the should be a 100 psi relief valve somewhere. Otherwise if it gets too high joints start bursting.

Its 110 now but I bet when your water heater runs and thermal expansion builds the psi its much higher. Also at night when no one in the community is using water pressures tend to rise.

Find the prv and adjust or replace. Also find the 100 psi reklief valve and change that while your at it..

That may fix your issue. But I also bet the washer came loose in that angle stop. Replace that too.

Dont forget to check expansion tank...

 

Do you turn the screw on the water pressure reduction valve counterclock wise to reduce the pressure after you shut off the main water valve? Some will say clockwise so it's important to know which direction to turn the screw.

I guess I was a little surprised I have a water pressure gauge built into the main pipe assembly by the builder.

 

Dont do nothing. That gauge is on the street side. You dont know what the house PSI is. You need to put a gauge somewhere to test. often the washer line or an outside house bib.

At least I think its on the street side..

Also since there is a PRV you must have an exp tank.. I can bet its faulty..

But your post is feeding us small tidbits at a time. If you show us all the piping there so we know whats what we can help you better. Also the exp tank. Water heater, etc...

 

There are gas company's gauge on the street side. I don't see one for water pressure. On the bottom of main pipe, this simply appears to be water meter. For my education, what is the PSI of 110 in the needle gauge I'm showing in this thread?

 

This appears to be BEFORE the PRV, so yes, it could be pressure from the street. If you take a pressure reading after the PRV, I am sure it will be less, probably in the 65 psi range.

 

OK so the water meter is below... So your line splits.

Left with the gauge of 110 psi is probably your irrigation system. Right is the home with the PVC.

1.You need to test the home side psi with a gauge to verify the PRV is working.
2. You need to find the expansion tank in the home and check.

High psi is the #1 cause of pipe banging IMO.

 

Merged threads. Your questions will be answered here. No need to start new..

 

How do I take the pressure after the pressure reduction valve? I understand I need to buy a water pressure guage. Do I take the pressure at the water heater faucet or outside spigot, or I guess both?

 

outside hose bib or disconnect washer hose and test cold water side.

Id really like to know if you have an expansion tank..

But if your not concerned I guess I shouldn't worry either and I should stop asking..

 

So do you mean 110 psi I'm showing in this thread is probably ok? I'll buy a water pressure guage and test. Where would I be able t locate expansion tank? Is it exposed inside the townhomes?

 

Should not be more then 80 psi in the home.

https://www.lowes.com/pd/WaterMaster...-Gauge/1126113

Expansion tank..

 

I don't have an expansion tank on top of water heater like you're showing in the pic. Maybe I don't have done, unless it's hidden inside the wall, which I think i doubtful. BTW, the needle gauge I'm showing in the thread, has tilted up slightly tonight. It was at 110psi, but it's now 120psi tonight. It sounds like this is the water pressure coming in from outside or from irrigation system. Can water pressure on the irrigation fluctuate?

I'll buy a water pressure gauge and try measuring it for inside of my townhome, and if it's normal, work on replacing on toilet stop valve with or without hiring a plumber. Is changing toilet stop valve something an average person can do with right size valve and plumber's tape? If I mess up, the main water valve must be shut off which will prevent me from using all faucets, washers, showers and toilet inside my home.

 

Yes water pressure from the street fluctuates. At night when the area is using less water pressure rises..

Since you have a PRV on your home side you have a closed system. A expansion tank is usually required by code.

Reason is when your hot water heats up water expands thermally. This raises the pressure in the home. Normally the pressure will push back to the street. But the PRV valve is also a check valve. So water cant push back and you homes pressure builds up. ( Until a faucet is opened)

But it will continue that cycle.

And if the prv is not working then you are getting that high psi on the house side. That plastic pipe will start bursting when it gets up over 100 psi..

Your in MD and I am suprised... You all follow the same strict code we follow here in NJ for plumbing... We are the only two states that follow that code...

 

I finally got a water pressure gauge, and did it from basement outside hose bib, and 1st floor outside hose bib. Basement was 55 psi, and 1st floor was 50 psi which seems to make sense because the higher you go the lower would be the water pressure in my opinion. It also seems like water pressure regulator in my basement is doing its job since the pressure coming in from street is about 100 to 125 psi as it fluctuates.

Now, since I don't appear to have high water pressure in my townhome, does that increase the likelihood the violent rattling/banging is due to the toilet water stopped in my basement bathroom? Your opinions are appreciated.

 

Could be a loose washer in one of the stops. The pressure is OK. But with a PRV you should have an expansion tank installed. The expansion tank my eliminate the banging..

Most times hammer arrestors are installed near the fixtures that make the pipes bang...

 

I just don't see the type of expansion tank you're showing in your pic. I don't think that type of the tank would be inside the wall. Not the in the boiler room in the basement where the water heater is.

I guess the next step would be for me to make a trip to Home Depot and check out the toilet stop valve they're selling and decide if replacing it is something I can do...... If I make an error, then I have to shut off the main water valve in my townhome.