Water pressure in new buildings - standard and possibilities for improvement?

That the pressure drops when an outlet is opened is correct. The question is, what pressure does the supplier provide at what height? When it goes uphill from the waterworks, less pressure is naturally available.

From 5 to 3.5 bar is too much. A pressure loss of 1.5 bar is quite a significant figure for flow losses.

The shut-off valves before the filter are fully open, I have checked that, as well as the large one behind it. I measured the pressure drop when opening the tap directly in the technical room. I still want to check whether it drops just as much at the shower.

I cannot answer what pressure is at what height. We have a basement but are already somewhat "on the hill" (You can tell I really know my stuff...^^)

Generally, one more question: The water pressure we are talking about only applies to the cold water, right? I basically like to shower warm... where or how is the water pressure for the hot water generated? We have a 300l water storage tank next to the gas boiler in the basement...

I was just about to say, isn’t it more about hot water? Do you have pressure problems at all outlets? For a friend, the cross-section of the water pipe to the shower was too small. The Rainshower is more like a drizzle.

There is a DVGW sheet W400 that regulates the pressure the supplier must provide; for buildings with a ground floor and one upper floor, a minimum pressure of 2.5 bar (static pressure) must be ensured at the transfer point (i.e., water meter). Normally, water pipes (inside the house) are built with DN 15, but for a proper rainshower, DN 25 is required, which the installer must know in advance.

I was just about to say, isn’t it more about hot water?
Do you have pressure problems at all outlets? A friend of mine had the cross-section of the water pipe to the shower sized too small. The Rainshower feels more like drizzle.

Yes... all the shower fittings also have a regular hand shower - and even with that there is hardly any power.

There is a DVGW sheet W400 that regulates the pressure the supplier should provide; for buildings with a ground floor and one upper floor, 2.5 bar minimum pressure (static pressure) must be ensured at the transfer point (i.e., the water meter). Normally, water pipes (inside the house) are built with DN 15; for a proper Rainshower you already need DN 25, but the installer has to know that beforehand.

We had informed the installer about the shower fitting (Grohe Rainshower 360 Duo) before he started the installation work. I cannot say what cross-section is where.

Maybe it is also just subjective – I don’t know what the pressure in bars was in the apartment. The fact is: with the shampoo it rinsed out within seconds there, here I have to use the shower for 20-40 seconds.