What Should I Know About Water Hammer?

Do you know that irritating, loud, banging and vibrating noise that you hear when you turn off the tap? It’s what we call a water hammer. A water hammer occurs when a valve is suddenly turned off which causes the pressure from the gushing water to suddenly stop. This high pressure then causes hydraulic shock waves that reverberate throughout the pipes thereby causing those loud vibrating noises that you hear.

We would need to differentiate though if the sound that you hear is from a water hammer or from trapped air inside the pipes. One simple way to do this is to determine when you hear the sound. If you hear the sound after you have turned on the tap, then that is trapped air inside the pipes. But if you hear the sound after you have turned off the valve, then definitely that is a water hammer.

Water hammer may only sound like a simple annoyance but we should not take it lightly. A water hammer can lead to a serious plumbing issue and can lead to a leaking pipe or burst pipe. The most common valve that causes water hammer to occur in your homes is the valves in your washing machines and dishwashers. These valves were designed to deliver more than the usual amount of water to the water fixture that they are connected which means that there is a higher water pressure coming from the flowing water on these taps. So when you suddenly close these valves, you now have the recipe for a potential water hammer.

Normally, when you shut off your valve or close the taps, the water pressure is diverted into the air chamber on the vertical pipes to cushion the effect of the water pressure rushing in when the water is suddenly shut off. The vertical riser, therefore, helps to minimize the water pressure and dissipates it before it reverberates throughout your piping system. But over time that air packet is lost and that’s when a water hammer occurs.