Mains water pressure

[allanb]

A couple of years ago we had a leak in the pipe bringing water to the house.  The plumber who fixed it commented that the house is fairly old, and the water pipes were probably not designed to take the pressure at which water is normally now supplied.  He suggested that he should fit a pressure limiter in the supply pipe; I agreed, and he did.

I think (but am not sure) that he mentioned something like 10 bar as a typical main supply pressure, and 4 bar as a pressure that would be adequate for the house.

Now for several months we have had a gradual drop in pressure in the house.  Most things still work normally, but the change is quite noticeable in the flow from the taps, and my wife thinks the washing machine is starting to function less effectively than it did.

I haven't yet been able to contact the plumber for advice.  I think he may have retired.  But in any case I have a basic question: if the pressure limiter was set to 4 bar, am I right in thinking that even if the mains pressure had fallen for some reason, as long as it was more than 4 bar, the pressure in the house should not be lower than that?

 

[Chancer]

The hydrostatic mains water pressure is not likely to change as you are almost certainly fed from a chateau d'eau, if you are at the end of an undersized or calced up water main the pressure may drop when lots of people consume water at the same time.

You are correct in your understanding of how the pressure regulator works.

Most likely the aerateurs in your taps are calced up, remove them and leave to soak overnight in vinegar and your pressure will seem to have doubled.

As to the washing machine you will have to explain what your wife means by functioning less effectively, in my experience this usualy means not washing as well, most machines will just take a little longer to fill but we are talking seconds compared to a wash cycle of often more than an hour.

Good luck.

[tenniswitch]

While you're getting ready to soak things in vinegar, be sure to check the ends of your water hose to the washer.  One (or both) will usually have a screen/filter on it.  When mine gets clogged up, it can take nearly half an hour to fill the washer drum.

[Chancer]

Good point, I threw mine away years ago as they never seemed to catch anything that might cause damage to the machine and what was the point of a filter that got blocked up with calc when my washing (90% work clothes) contained brick and tile dust, mortar, wood shavings, meatal swarf and assorted scerws and nails none of which have damaged the pump.

[allanb]

It's fixed.  I think it was the aerators in just two or three taps.  I'm sure I heard about the vinegar tip a long time ago, and I'm ashamed to say that I'd forgotten it.

Next I'll get to work on the washing machine.  In the meantime, thank you very much.

[Chancer]

Mine need doing every month, they get done once or twice a year, no problem so far with the filterless machine lave linge but the chasse d'eau sometimes needs a good thump.

[napoleon]

 

[quote user="allanb"]

I think (but am not sure) that he mentioned something like 10 bar as a typical main supply pressure, and 4 bar as a pressure that would be adequate for the house.

[/quote]

I am surprised at these figures. Maybe that's because am in a region that has a maximum pressure of 3 bar (about three times the pressure in the UK). I can understand why the plumber put in the reducing valve. What pressures do other members have?

Alistair

[JohnRoss]

I think our pressure was at least 6 bars when we moved in and the chauffe eau burst, quite old, a week after we moved in so I bought a pressure regulator from the local Brico and fitted it to the feed pipe coming into the house. With the control screw fully unscrewed I have got the pressure in the house down to 3.5 bar with all the taps off. Turning a tap on causes a pressure drop to 2 bars which is not a problem as long as you don't do it when someone is in the shower! Not really very satisfactory and I have changed the regulator once in the last 9 years. I have no way of knowing how accurate the pressure gauge is which is plumbed into one of the cold water pipes. I do take out the inspection screws on the regulator to look for muck from time to time but there are no filters.

In the UK we were near a pumping station and the pressure was much too high, actually blew up the valve in one of our loos and also the pressure gauge of a water board technician who came to check the pressure. The comment he made is not printable! I gather the water main was too small for the load of lots of new houses further down the line so they just put the pressure up to compensate.....................................JR

[Chancer]

I have a feeble 2 and a bit bar here in France yet calculating the static head from the chateau d'eau I should have more than 5 bar, I am at the end of the distribution and there are farms and an aircraft factory upstream of me, the pressure used to drop to nothing every Thursday evening when they must have been purging something but it seems stable now, my problem is that I am creating flats on the 3rd floor of my building, I have done a test with a hosepipe and shower head and its just about OK but if all 7 flats use the showers at the same time I reckon we will have problems. I think that there must have been problems in the past and that there is some form of regulator in the water main in the street.

In the Uk I was surprised to find that I have 6 bar, but of course still a weedy gravity fed shower, when I converted an outbuilding I used a French ballon and cabin de douche, if you use the hydro jets you step out of the shower bleeding!