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How Do I Stop Water Hammer In My House?


Ever wondered why your pipes make those crazy banging noises from time to time, like a neighbour angrily hammering on the wall? This is known as water hammer, and is usually caused when an appliance such as a washing machine or dishwasher suddenly shuts off – or when a fast running faucet is closed abruptly. In technical plumbing terms it is known as a hydraulic shock, the shock coming at the abrupt halt or change of direction of the water which causes the pipe to move and bounce against other pipes or fixtures. Obviously, having your pipes jolting like this is not good – it can lead to damage to the pipe or whatever it is banging against. Aside from that, it’s very annoying, so it’s best to get it sorted before it becomes more than just a regular headache! Here are some tips (maybe check it isn’t an irate neighbour first. 

The basic method

This is a simple list of tips which may stop the problem without having to remove, install, refit or replace any fittings at all. Start by shutting off the water supply to the whole house at the main. The open all the faucets in your home, starting with the top floors. Flush all the toilets, then wait for about half an hour. This should allow all the water to drain. Turn on the main water supply and wait about 10 minutes to allow the plumbing to return to its full power. Make sure all the faucets are closed, then flush the toilets to see if you experience water hammer. This is by no means a fool-proof test, so you may need to investigate further even if you don’t experience water hammer straight away.

Older plumbing?

If you’re without air chambers then this is an issue that needs addressing immediately.  In some cases the installation of a pressure reducing valve is a good one – gate valves are one of the most common types of valves used in plumbing. Pressure becoming too high in pipes is a common cause of water hammer, so this might help. Again, seek professional help if you need it!

Check your air chambers

Good quality (or more modern plumbing) will come fitted with air chambers which cushion and compress that shock, reducing or eradicating water hammer. So if your plumbing is relatively new, or has just started hammering this might be a good starting point to investigate. They can become waterlogged, so by turning off the water behind the chamber and allowing it to drain thoroughly, this could help. If you’re not confident with the DIY  it’s always best to look for a reliable plumber for this or any of the suggestions on this list. 

Check for loose pipes

It’s possible for pipes to become loose over time, so it’s worth periodically checking them to prevent water hammer, or if you are experiencing it. Start with the most accessible ones, which are uncovered. Usually these can be found in the basement or the attic or any utility rooms that you may have. If the water hammer is mild it may be enough to secure and tighten any loose piping, or to insulate the pipes with foam. But if the water hammer is  more severe it may have caused damage to the pipes (or be about t), and this could mean replacing them entirely. When replacing pipes remember to use similar metals – consult your plumber if you’re unsure – mixing metals can cause corrosion and lead to even more problems. 

Pressure reduction

We touched on this before, but a full overhaul of your valves, or a dedicated pressure reduction system may get rid of water hammer entirely. Pressure reducing valves are not to stem the flow of water but are designed purely to reduce the pressure of the water in your pipes. These are most commonly found in homes which have high water pressure from the local water board, which may be contributing to your water hammer problems. It’s usually best to install a pressure reduction valve at the point the water enters your home, but again, consult a professional if you need some extra help. This is worth doing properly, as very high water pressure can damage appliances as well as pipes, which is costly or will ruin your home contents insurance premium (as well as being immensely inconvenient). 

Ultimately water hammer can vary in scale from a mere annoyance to a genuine threat to the plumbing facilities and related appliances in your home. Hopefully these tips will give you a bit of confidence when it comes to troubleshooting, fixing (either yourself or a plumber) and general maintenance.