Why does water pressure drop when another faucet turns on?
Water pressure can drop significantly or go to almost zero when multiple fixtures are used simultaneously, sometimes linked to recently installed equipment like a new water heater. This sudden restriction leaves households with conflicting pressure readings and forces them to wait ten minutes or more for the system to recover after closing the fixtures.
What people tried
Every workaround mentioned in the threads below. We haven’t tested any of them — and nobody here is claiming they worked.
- 1adjusting the pressure setting
- 2taking the PRV apart
- 3cutting the shutoff valve off multiple times
- 4waiting for system pressure to build up with all fixtures closed
In their words
Unedited, grouped by where they were said, most upvoted first within each place, each linked to the thread it came from.
“when a 2nd water source is being used, the water pressure is dropping significantly.”source ↗
“I keep getting conflicting results when I check the pressure.”source ↗
“Now, if someone is showering and someone flushes a toilet, the pressure drops to almost zero on the Radon water system pressure gauge and wont build up until all fixtures are closed for 10+ minutes.”source ↗
“We didn't have this issue before the new water heater and I'm confused why installation of a new one would make a difference.”source ↗