It can be somewhat unsettling to turn on a tap or your shower and to hear a loud banging sound as the water begins to flow. It sounds as though someone is hammering inside the wall, which is why this occurrence is known as water hammer. It can be caused by air trapped inside the pipes which is being released when the water is turned on. It can also happen when the water pressure is simply too high. Ongoing water hammer can cause damage to your pipes from the vibrations and excessive pressure. So what can you do to prevent water hammer and the stress it causes to your pipes and fixtures?
If the hammering noise is infrequent, then it's probably caused by a small amount of trapped air inside the pipes. This is not a cause for alarm and is unlikely to become a regular event. Since it's fairly infrequent, any damage caused to your pipes is too minimal to worry about. The air will be expelled and the fixtures will operate as they should. It's when it happens more often than not that you need to consider that your water pressure might be too high.
Regular occurrences of water hammer can be fixed with an anti hammer control valve. This small, useful valve essentially operates as a pressure regulator. Generally made from durable brass, they can simply be screwed into place. The control valve is fitted between the connecting pipe (which supplies the water) and the tap washer, which is then connected to the basin flange or jumper valve. If you install the control valve yourself, please remember to turn the water off first. If the fixtures are built into the wall (which is often the case with showers), you might need to call a plumber. The plumber will be able to loosen the fixture and extract it from the wall without causing any damage. The control valve is then fitted, and the fixture is put back into position.
If the water hammer continues even after the control valve has been installed, the culprit might be your choice of taps or shower head. These fixtures are often chosen for their aesthetic value as opposed to their flow capabilities. Sometimes the fixture does not allow water to be expelled at a sufficient speed or volume to match the available water pressure. In these cases, you might need to consider changing the fixtures in question. It's an inconvenience, but it's better than causing ongoing damage to your pipes which can be even more of an inconvenience in the long run.
Water hammer is an annoyance, but it can turn into a big problem for your pipes if you don't take the necessary steps to fix it.