40m doesn't seem at all surprising if you consider the height of a water tower built somewhere with higher elevation than most of the town. My house is 20m lower than the base of either of the two nearest water towers, at least one of which is ~75m tall. A few years ago, the town completed migrating one of the outlying areas with lots of new development into their central pressure zone, resulting in an increase by 45psi in those neighborhoods.

Pressure reducing valves are used anywhere the pressure going into a home is above 80 PSI, and those are a lot more common than homes needing their own booster pumps.

Sorry, for got to mention. Most of India does not have direct water connections.

Most homes have borewells, storage tanks and intermitten municipal supply. So there is no direct line from local municipal water tower to homes.

> Pressure reducing valves are used anywhere the pressure going into a home is above 80 PSI, and those are a lot more common than homes needing their own booster pumps

My house has one of these, as the pressure would go up to 90 psi sometimes (iirc). Weirdly, my water pressure isn't consistent and can still burst to a "visibly from the tap" higher pressure for a few minutes at a time. I have no idea what causes it.

I wonder if it's from water expanding in the hot water heater. That might be pressurizing your system after you send a volume of cold water into the heater after use. Your pressure reducer valve might be acting like a check valve preventing expansion relief into the municipal supply.

An interesting premise, but I am on a well, have a pressure tank, and the well hose/pump has a check valve.

(Otherwise, water could slowly drain back into the well)

So think of it as a closed system, and it is a common setup, yet I have not seen this behaviour.

I have to _reduce_ the mains to 55psi to keep my water heater functioning.

Plenty of pressure here (USA) without a pump.

4 bar is the normal house inlet pressure in Norway. In fact in some places the mains pressure is much higher and a pressure reduction valve is fitted. No one uses header tanks.

nah, just one pump. The well is about 518'/158m deep, so the basement +2 stories are kind of a small add-on. I seem to recall most of the bog-standard plumbing bits are rated at 120 or 150 psi. I just put in some new PEX line extensions and that stuff is rated for 160psi at 74F, 100psi at 180F and 80pis at 200F. (BTW, very good experience installing the PEX, as long one takes care to make clean cuts, it's great - I'm about to go test it for vacuum lines at my shop)

Edit: Plus, I've got to say that it is really cool to get perspectives from all over the world here - India, Norway, and a few other places, just in a few comments - just how differently things are done, and what we each take for granted in our environment.