Home & Garden

Ask Angie: Several problems could cause rattling in water lines

Angie Hicks
Angie Hicks MCT

Dear Angie: Our two-story home has 41/2 bathrooms, which all seem to have a common cold-water pipe that runs through a particular wall and ceiling. In four of the baths, when the toilet is flushed, the water cutoff causes the pipes to vibrate very loudly in the wall or ceiling. Turning off the cold water faucet at the sink also causes a vibration.

We've had three plumbers out. They have cut through walls in two rooms and failed to locate the section of pipe causing the problem.

Is there a tool a plumber could use to locate the problem area before cutting through the wrong area of walls/ceiling again? Or, is there another way this problem could be resolved? — Claire K., Nashville

Answer: There could be a few things that cause the rattling noise in the pipes behind the walls, so that means there's more than one option to solve the problem. Fortunately, none of them should be too invasive.

To start, the problem could be a loose pipe, which would need to be secured to the wood framing with pipe clips. Ideally, this could be done by getting to the pipes via an access panel or an open area where the pipes are exposed, such as a basement, rather than cutting through a wall or ceiling. Visibly inspect your pipes in open areas to see whether there is a lot of movement when someone turns faucets on and off or flushes a toilet.

Another problem could be that your water pressure is too high. That can cause pipes to vibrate and lead to long-term damage to your pipes and appliances. Highly rated plumbers I've spoken to in your area say the indoor water pressure should be 40 to 60 pounds per square inchI. Adding a pressure-reducing valve to your incoming main line could correct high pressure, if that's your problem. You can buy a water pressure test gauge to test the pressure yourself, or a qualified plumber can test the pressure for you.

Finally, you could be experiencing a common occurrence known as water hammer. Water hammer is caused by fast-closing valves, such as toilet fill valves and faucets. As the water flows through the pipes and the valve shuts off quickly, it causes the water to stop suddenly in the pipes, causing the "hammer" effect. Adding a water hammer arrestor to the offending pipes could correct this, but that can involve cutting and soldering pipes and probably would require a plumber. Again, ideally, the plumber could add the arrestor to the pipes where they already are exposed. One possible simple solution to water hammer could be to replace your toilet fill valves with slow-shutting fill valves.

If you've lived in the house for a long time and the hammering effect has gotten worse, it could be that you have air chambers connected to your pipes behind the walls. Air chambers help cushion against water hammer, but they fill with water over time and need to be drained to allow them to refill with air. Most homeowners can do this easily by shutting off the water main valve, opening the faucets and flushing the toilets, starting at the highest level of the home and working down to the lowest level, until all the pipes have drained. Once water stops running out of the lowest pipe, close that drain and turn the water main back on.

The noises you hear aren't just aggravating. They could cause a pipe to break because of the force of the banging. Water damage can be devastating and expensive to repair, so be sure to find a reputable plumber to help diagnose and treat the problem.