How do I tell if my mains water pressure is good?

[MisterBoy]

Running a single tap I get a good rush of cold water but doing anything else it dwindles a lot. I know the classic "flush the toilet and someone gets scalded in the shower" but this seems to be much more extreme than I've had in other properties. No idea if our pressure might be a bit low or it's outrinternal plumbing.

Is my first job simply to ask the water provider to take a look - is testing the pressure something they'd routinely do?

 

[JohnD]

how old is the house? or are you in a flat?

what is the incoming water pipe made of (or its colour if you can't tell) and diameter?

BTW you say "pressure" but it's more likely the "flow" at fault. Turn off all taps, stand in the kitchen, put your thumb over the spout of the cold tap and turn it on. Can you hold back the pressure?

Now fill a bucket and time it. How many litres per minute does it deliver?

 

[MisterBoy]

how old is the house? or are you in a flat?

what is the incoming water pipe made of (or its colour if you can't tell) and diameter?

Thanks John. It's a Victorian house in a rural location with a dedicated 100m supply from the mains on the street. We have rarely seen the supply as it is buried but I am led to believe it's some sort of 3" cast iron pipe or something like that.
For reasons we don't understand we have not 1 but 3(!) stop cocks into the house from this - kitchen, utility room and outside tap.

Actually that makes me think I can test if turning on the outside tap reduces the kitchen tap pressure, etc - tell me something if it's our internal plumbing?

 

[Madrab]

Buy a pressure gauge, get one from the local sheds.

Attach it to an outside tap or appliance valve, as close to the mains as possible. Take 3 readings. One with no water running (static pressure) another with one tap running (woirking pressure) and then a final one with several outlets open >2 (peak dynamic pressure).

Also test flow, run the water into a bucket, time that over a minute. Then measure how much water there is is litres, that will give you the flow in L/Min.

Depending on those figure will determine how good am mains service you have. How rural are you? that can also have an effect on the service you receive as well as the time of day. You really want to do the tests at peak usage times as that will show worst case, which is really what you want to know.

 

[MisterBoy]

Thanks @Madrab I didn't know that existed for domestic use - this sort of thing I assume it has the standard outside tap thread: https://www.screwfix.com/p/monument-tools-mains-water-pressure-test-gauge-11bar/82412

Any idea what figures I want to see, or what would constitute bad results? The "fill a bucket " test is nice and simple too I like that as long as I know what sort of rate I am hoping for.

 

[Madrab]

That's the chap

Anything above 2/2.5 bar dynamic @ 20L/Min is nominal for most domestic properties say up to 3 bathrooms and /or unvented HW

Anything below 1 bar dynamic @ <=10L/Min, IMO, is a poor service.

Everything in the middle is OK, depending on what the service needs to provide for within the property.

 

[CBW]

Have you checked the incoming stopcock and any above are fully open?

 

[MisterBoy]

Have you checked the incoming stopcock and any above are fully open?

I've checked the ones our side of the water meter - is that what you mean, or is there one on the main supply to check too (i.e. if they wanted to disconnect us?)

 

[CBW]

Yes, I meant your side, this wasn’t mentioned in the OP or replies. You will likely have one outside (usually called a boundary stopcock), this maybe closed off too, but up to you if you want to check it?