Having problems with loud banging coming from the pipes in the wall behind your washing machine? That is water hammer, which happens when the shut off valve suddenly closes on a high-pressure water line like the one to your washing machine. As the washer fills with water the water coming in through the pipe rushes in quickly. When the drum is full the valve to the washer closes abruptly. That fast-moving water has nowhere to go now and so inside the pipe slams against the sides in strong surges under the pressure. That makes the pipes jerk and then bang against the other pipes and the wall. It makes a loud banging noise and can lead to problems and damage with the joints and pipe connections. To avoid costly plumbing repairs it makes sense then to look for water hammer solutions.
Check the air chamber
There is a vertical pipe that acts as a cushion found near the water valve called the air chamber. When the valve shuts the air chamber is meant to absorb that shock of water and stop it from slamming in the pipes. Some homes have air chambers that are in the walls but sometimes if it gets waterlogged it can stop doing its job. This means you need to drain the system to fix it. First, shut off the mains water valve and then open the highest tap in the home and drain water from the lowest tap. This should lead to the air chamber re-filling with air, not water and that should now cushion the pipes so there is no banging. Now if you do not have an air chamber you might want to have professional put one in for you.
Have water hammer arrestors installed
Another option for your water hammer solutions is to have arrestors installed. These are cylinders that are filled with air and will absorb the sudden jolts of water pressure when the valve is shut off. Most are quite easy to put in and you could do it yourself, or you can bring in a professional to do it for you. They attach between the shut-off valve and the water supply line with a screw connection. You should install two, one on each of the hot and cold water supply lines.
Regulate the pressure
The pressure-reducing valve can be adjusted so that the pressure is better regulated. This valve is where the main water supply valve is. Some have a handle and some might need a simple screwdriver or wrench. Adjust it to less than 50 PSI and you get the added bonus too of saving energy and doing better at water conservation. It will also help extend the life of your appliances like the dishwasher and washing machine, as well as the toilets.
Reduce pressure at the meter if there is no pressure-reducing valve
In cases where your home does not have a pressure-reducing valve, you can get in touch with those in charge of the water system where you live to ask about the water pressure. Most will check the pressure and reduce it if it needs it.
Fasten loose lines
Sometimes when constructing the home, the plumber might not have made the straps tight enough that fasten water supply lines to studs with screws or to wooden joists. If they loosen, or if not enough are used the pipes start to knock around more and make the noise. As one of your potential water hammer solutions, you could use a screwdriver to tighten those pipe straps or put in new ones. You can get different straps, the more common being plastic and thin metal. You can get padded ones too though for an added reduction in noise. Do not use galvanized straps or steel straps though if you have copper piping as that can cause big problems.
Put in some pipe insulation
Insulation is another of the water hammer solutions you or a plumber might opt to use. It can fit around the water lines to stop then freezing and also works great to cushion them and prevent banging. They are easy to open and fit over the lines and are cheap too and you can get different thicknesses.
