ᐅ Water Pressure in New Construction – Standards and Possible Improvements?

Created on: 19 Dec 2017 14:56
D
DReffects
Good day,

we recently had a single-family house built, and now the shower fittings are installed. Unfortunately, the water pressure is so low that the lady (and I a bit as well) have trouble getting the shampoo properly rinsed out.

The rain shower with massage function is more like a hesitant trickle. It’s not due to the showerhead itself; we tested by connecting the old showerhead from our rental apartment, and the water pressure is clearly lower here as well.

I have several questions:
- Is there a standard regarding water pressure?
- How can water pressure be measured? Possibly without removing the fittings...
- What options are there to increase the water pressure?

Thanks!
T
toxicmolotof
19 Dec 2017 22:35
It is correct that the pressure drops when an outlet is opened. The question is, what pressure does the supplier provide at which elevation? If the water has to be pumped uphill from the treatment plant, less pressure naturally reaches the destination.
K
Knallkörper
19 Dec 2017 23:39
Reducing from 5 to 3.5 bar (72.5 to 50.8 psi) is too much. A pressure loss of 1.5 bar (21.8 psi) is quite significant for flow losses.
DReffects20 Dec 2017 00:04
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 faucet directly in the utility room. I still want to check if the pressure drop is as significant at the shower as well.

I can’t say what the pressure is at which height. We have a basement but are also located somewhat "on a hill" (You can tell I really know what I’m talking about...^^)

One general question:
The water pressure we are discussing applies only to the cold water, right? I usually prefer to shower with warm water... so where and how is the water pressure for the hot water generated? We have a 300 liter (79 gallon) water storage tank next to the gas boiler in the basement...
A
Alex85
20 Dec 2017 02:30
I was about to say, isn’t it more about the hot water?
Do you have pressure problems at all outlets? A friend of mine had the water pipe diameter to the shower sized too small. The rain shower felt more like a drizzle.
A
alexm86
20 Dec 2017 12:09
There is a DVGW sheet W400 that regulates the pressure the supplier should provide. For buildings with a ground floor and one upper floor, a minimum pressure of 2.5 bar (36 psi) at the handover point (i.e., the water meter) must be ensured at rest pressure. Usually, water pipes inside the house are built with DN 15 (15 mm / 0.6 inches), but for a proper rain shower, DN 25 (25 mm / 1 inch) is needed. The installer must know this in advance.
DReffects20 Dec 2017 21:37
Alex85 schrieb:
I was just about to say, isn’t this more about the hot water?
Do you have pressure issues at all outlets? A friend of mine had the water pipe diameter to the shower undersized. The rain shower felt more like a light drizzle.

Yes... all the shower fittings also have a standard handheld showerhead – and even with that there is barely any pressure.
alexm86 schrieb:
There is a DVGW sheet W400 that regulates the pressure the supplier should provide. For buildings with a ground floor and one upper floor, a minimum pressure of 2.5 bar (36 psi) (static pressure) at the supply point (i.e., the water meter) must be ensured. Usually, water pipes inside the house are made with DN 15 (½ inch) diameter; for a proper rain shower, DN 25 (1 inch) is needed, but the installer needs to know this in advance.

We informed the installer about the shower fitting (Grohe Rainshower 360 Duo) before he started the installation work. I can’t say now what diameters are used where.

It might also be somewhat subjective – I don’t know what the actual pressure in bar (psi) was in the apartment. The fact is: shampoo rinsed out within seconds there, but here I have to use the showerhead for 20–40 seconds.