I noticed my water flow at my faucets sometimes drops a few seconds after been turned on, so I tested my water pressure using a meter.

  • I get 84 PSI (I know, it is slightly too high) when not using the water.
  • I get 55 PSI (a drop of 30 PSI) when I turn on just one faucet.
  • Turning on 2 more faucet does not change the water pressure and it remains at 55 PSI.

What problem(s) do I possibly have?

  • Lacks anything like sufficient details. Water comes from a well, or an elevated spring/tank, or a municipal supply? You do or don't have a pressure regulator (aka pressure reducing valve or PRV?)
    – Ecnerwal
    Commented Aug 17, 2023 at 16:43
  • Certainly looks like a constriction somewhere that limits flow rate. Valve not fully open, pressure regulator failing if you have one, someone having bent a pipe or done a particularly bad solder joint...
    – keshlam
    Commented Aug 17, 2023 at 17:50
  • 1
    Constrictions reduce flow rate past the constriction, but when flow is stopped the flow past the constriction continues until the pressure is balanced. When flow near the end of the run is opened typical compression of air in the pipe will cause a detectable burst until flow is reduced to capable flow past the restriction. That constriction could be a pinch, too many bends, a section of pipe that is too small, rust build up in iron, plugged filter, damaged pressure regulator, the list is almost endless. Commented Aug 17, 2023 at 19:33
  • Thank you all for your comments. I am living in a 20-year old subdivision using county water. The community is well established and not too old. There are two new smaller subdivisions are under construction nearby, not sure these would have anything to do with my problems. I will replace the 20-year old pressure valve to see what happens (I have black particles on my whole house filter even after they came flushing to water lines three times in a week.
    – dec101
    Commented Aug 19, 2023 at 1:53

1 Answer 1


I had a very similar problem in a house where I used to live, where the house received city water: high pressure at first then drop to low pressure. The water pressure regulator was bad. Replacing the regulator restored normal steady-pressure operation.

At the house I live in now with well water, the water pressure comes out high then drops low when the main water pre-filter gets clogged. The water can slowly push through the clogged filter to high pressure, but drops low because the flow cannot get through the filter fast enough. Replacing the filter media restores normal steady-pressure operation.

Either of these may fit your situation.

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