The short answer
Mains pressure above about 500 kPa shortens the life of every tap, flexible hose and appliance valve in the building. Testing takes minutes with a gauge at an outside tap. The fix is a pressure limiting valve at the meter, which is a small part and a short job.
The complaint nobody makes
Nobody calls a plumber about high water pressure. They call about a tap that keeps dripping after it was just repaired, a flexible hose that let go under the vanity, a cistern that will not stop running, or a dishwasher that failed two years out of warranty.
Those all look like separate problems, and they get treated as separate problems. Often they are one problem wearing four different hats.
What the number should be
A gauge on an outside tap tells you in about a minute. Anything up to roughly 500 kPa is a comfortable working range for a house. Plenty of Melbourne properties are sitting well above that, because the network has to deliver enough pressure to reach the worst-served property in the area, and if you happen to be near the good end of that run you get the surplus.
On a recent job the reading came back at 700 kPa. Nothing had failed yet. That is exactly the point at which it is worth doing something, because at 700 kPa every one of these is under constant strain:
- Tap and mixer spindles, which are sealing against that pressure every time you close them
- Flexible braided hoses under sinks and vanities, which have a finite life and lose it faster under load
- Toilet cistern inlet valves
- Solenoid valves inside dishwashers and washing machines
- Every soldered and compression joint in the building
Why high pressure feels good
Because for the first few years it is genuinely pleasant. The shower is strong, the taps are responsive, filling a bath is quick. The cost is not in performance, it is in service life, and service life is invisible until something fails.
The failures also tend to get blamed on the wrong thing. A hose that bursts at five years gets called cheap. A mixer that drips again six months after a repair gets called a bad repair. Neither diagnosis looks at the pressure that is common to both.
The fix
A pressure limiting valve fitted at the water meter. It holds the pressure downstream at a set figure regardless of what the mains is doing, so the house only ever sees the pressure it was designed for.
On the 700 kPa job it was brought down to a steady 500 kPa. Small part, short visit, and it quietly removes the next decade of leaks that would otherwise arrive one at a time and get blamed on bad luck.
Worth knowing: if your property already has a limiting valve, it can fail, and it usually fails by drifting upward rather than shutting off. A valve fitted fifteen years ago is worth testing rather than assuming.
What to do about it
Get the pressure tested. It takes minutes, it needs a gauge rather than a guess, and a reading that comes back fine is still useful information because it rules the pressure out as a cause of everything else.
If it comes back high, you now have one job to do instead of an unpredictable series of small ones.