A water pressure regulator is a plumbing safety feature which is designed to prevent water pressure from climbing too high while also ensuring that the pressure remains high enough for consistent flow from faucets, taps, and shower heads. This device is often located near the water main on the outside of the house, and it is very useful for people to know where their water pressure regulators are, and how to adjust them if necessary.

Plumbing works because of the water pressure. When the pressure is high enough, water will be pushed through an open tap, even if the outlet for the water is well above ground level. However, pressure which is too high can result in leaks, eroded washers, banging pipes, and even explosions, in extreme circumstances.

A water pressure regulator is a valve which controls the level of water pressure to ensure that it is effective and safe. In a multistory building, each floor may have a water pressure regulator in place, since higher levels of pressure are needed on high floors to successfully push the water up.

Classically, water pressure hovers somewhere between 40 pounds per square inch (2.8 kilograms per square centimeter) and 60 PSI (4.22 kilograms per square centimeter). Most water pressure regulators have an adjustable dial which can be used to increase the water pressure in the event that water is merely trickling out of taps, and to decrease the pressure if the water pressure is too strong. Some also have valves which open up in a pressure surge to allow water to harmlessly flow out, rather than blowing through the plumbing system.

Water heaters have a special type of water pressure regulator which is called a temperature pressure regulator valve (TPRV or TPR valve). The TPR valve is designed to open if the pressure or temperature inside the hot water heater grows to a dangerous level, allowing the pressure to vent harmlessly, albeit sometimes messily. If this valve becomes damaged or defective, there is a risk of an explosion caused by extremely high pressure inside the water heater.

Familiarizing  with safety features like water pressure regulators, main water cutoffs, and breaker boxes is a very good idea, so that they can be accessed quickly in an emergency. It is also a good idea to periodically test these safety features to ensure that they are working smoothly; it should be easy to turn the valve or knob with the assistance of a pair of pliers or vice grips, for example, and there should be no signs of corrosion leakage, or stress on the surrounding joints.