Pressure regulator
A valve that lowers incoming city water pressure to a safe level for your home.
A pressure-reducing valve (PRV), usually found where the main line enters the house near the [main water shutoff](/glossary/main-water-shutoff), drops the high pressure from the municipal supply to a house-safe 50–60 psi. When it fails, pressure either creeps too high — stressing pipes, appliances, and supply lines until something bursts — or drops too low, leaving every fixture weak. A failing regulator is a common, fixable cause of sudden whole-house pressure changes; testing pressure with a cheap gauge confirms it.