Renovation & Design

Diagnosing rattling plumbing sound could get invasive

Question: I live in a two-storey townhouse condo, which is about five years old. When you flush the toilet, on either level, the pipes seem to make a rattling sound. What would you suggest?

— Barb Heppner


Answer: Noisy plumbing is a common issue, which rarely causes any serious problems and can be quite annoying to home occupants. This may be attributable to poor workmanship or pressure changes at fixtures — figuring out which is responsible will determine the proper course of action to alleviate the issue.

Hearing a noise when plumbing fixtures are operated can range from being quite normal to excessive, depending on the situation.

By your description, it appears the "banging" noise is toward the more concerning end of the spectrum. Many fixtures will have noises attributable to simple movement of water through the pipes and faucets.

Some may be relatively quiet, while others will be audible in various areas adjacent to the room where the plumbing fixtures are located. Toilets can have very noisy flushes, or almost silent ones, depending on the design and tank parts.

Unfortunately, there is often little testing or information on noise levels available prior to purchase. If this is what is going on in your building, there may be nothing to do other than replacing the noisy fixtures.

Since your description sounds different than typical water flow noise, there is likely one of two causes for the disturbance.

Similar to water flow issues, some fixtures may allow a larger than necessary flow of water immediately after the fixture is activated. This can create a sudden pressure change within the supply pipes, which is sometimes heard as a banging noise. This is often referred to as "water hammer" and is much more common with really old fixtures.

Opening and closing the valves more slowly may prevent the sudden pressure differential and thus the noise. Special water hammer arresters can be installed near the fixtures, but are normally only used when all other options have been ruled out. Since your problem is with toilets, the first option is not applicable.

If your toilet issue is caused by too high initial water volume, then changing tank parts, or the complete fixtures, may be the easiest solution.

Installing new tank parts is quite simple, but determining which brands have less problems may take some research. Many licensed plumbers will have experience with this issue and have their preferred type of toilets or replacement parts to solve the issue. The other option, which I don’t recommend, is to partially close the valve supplying the toilets, to slow down the fill rate of the tank. While this may work, you may find that the tanks take an unnecessarily long time to fill, which can be overly noisy in its own way.

The second scenario for the banging pipes is poor securing during installation.

As previously mentioned, there can be a considerable initial pressure change within the water supply pipes when any fixture is operated. If the pipes are not well-secured to the building framing, they can vibrate when something is turned on. This can cause them to literally bang against the framing, making loud sounds. In that case, the repairs can be much more extensive.

Opening up walls and/or ceilings will likely be required to access the offending pipes, to install proper anchors.

Diagnosing the exact areas where the loose piping is located may be even more difficult than accessing them.

Since your building is quite new, determining the type of water piping installed may help to figure out which of these two scenarios is more likely. Since most residential buildings are now plumbed with PEX supply pipes, that would be the most logical guess. This semi-flexible plastic piping is easy to cut and install, with metal crimp rings used to connect fittings and pipes. PEX pipes are normally secured to wall and floor framing with C-shaped plastic clips, nailed or screwed in place. These are designed to be held with only one fastener, which allows some flexibility. Because PEX pipes may expand and contract with changes in temperature, this style of clamp allows for minor movement without damage.

Unfortunately, I have observed numerous situations where these plastic clamps have broken, even in relatively new homes. This may be due to their composition, or poor installation of the pipes under pressure, which causes mechanical damage to the clips. Once several clamps have let go of a pipe, it will be much more likely to move around when fixtures are operated.

To complicate matters even more, your building could be plumbed with copper water supply, due to its design. Since it is a multiple-family dwelling, fire separations are required between units, which may not allow plastic pipes to penetrate these barriers.

In that situation, many newer plumbers may not be well experienced in copper pipe installation. That makes it more likely that the pipes are not properly secured to the framing, allowing movement with sudden pressure changes.

Consulting an experienced plumbing contractor, and maybe the original builder, will be required to review original installation methods. Opening walls and ceilings will be necessary, to inspect the pipes for poor installation.

Loud noises from toilets or faucets are usually attributable to either poor design or sloppy securing of the supply piping.

Replacing the toilets or tank parts may alleviate the problem, otherwise opening up walls and ceilings will be warranted to allow an experienced plumber to locate and fix the offending pipes.

Ari Marantz is the owner of Trained Eye Home Inspection Ltd. and the past president of the Canadian Association of Home & Property Inspectors — Manitoba ( Questions can be emailed to the address below. Ari can be reached at 204-291-5358 or check out his website at



Browse Homes

Browse by Building Type