Welcome to the forum. Although you can post in any forum, the USA forum is here in case of local regs or laws

Install the app
How to install the app on iOS

Follow along with the video below to see how to install our site as a web app on your home screen.

Note: This feature may not be available in some browsers.

Nov 27, 2017
7
2
3
42
Reading
Member Type
DIY or Homeowner
Hello, may be a strange concern but just got some questions about the water supply to my cold water kitchen tap. It has always had poor pressure and if using water in upstairs bathroom this gets even worse. I just had a combi boiler fitted so the cold water tank in roof has been removed and everything connected to the mains water supply. The kitchen tap is now running at full pressure and the water seems much colder. I told this to the plumber and he said it may have been connected to the cold water tank before instead of the mains although shouldn't have been! I am now worried I have been drinking tank water for the year I have lived here! However, now everything has been changed over I can't see a way of checking this. The washing machine supply also stems off the cold water to kitchen tap supply. Can one pipe use mains and tank supply for different outputs? Is there any way I can now check? Could there have been another reason for the poor pressure? Thanks in advance.
 
Can one pipe use mains and tank supply for different outputs? Is there any way I can now check? Could there have been another reason for the poor pressure? Thanks in advance

Hello,
No, one pipe can't use two separate types of supply.

If you are in a house in a town or city I would say it would be unusual for your kitchen sink to be a tank fed supply. Not impossible though.

Is it more likely that the stop tap was nearly closed and due to the Plumber working on the cold water pipes, he/she has opened it up fully?

Just thinking out loud!
 
Hello,
No, one pipe can't use two separate types of supply.

If you are in a house in a town or city I would say it would be unusual for your kitchen sink to be a tank fed supply. Not impossible though.

Is it more likely that the stop tap was nearly closed and due to the Plumber working on the cold water pipes, he/she has opened it up fully?

Just thinking out loud!

Thanks, the plumbing under the kitchen sink is a bit of a mess so not sure if the last person was doing a bit of an amateur job and they connected it up wrong...!! However, a while ago my dad did a pressure test on the washing machine supply and said was good. (he was doing it to see if there was enough pressure for a combi) Yet the tap right next to it had really bad flow until the recent work was done. If the stop tap was partially closed I would assume the pressure test would have been low, although I also assume that if the washing machine was off the tank the pressure wouldn't have been as good? It's all a mystery and I just wish I'd checked before the work was done now!
 
The pressure test would just show the pressure, not the flow of water, so the stopcock could still have been turned down too low. Pressure remains same

Oh okay, thanks. So if the supply was from the tank where he tested it would probably be low as relying on gravity? Am just thinking that as the pressure was good it is more likely to be a mains supply. (although I don't know what pressure water can get up to from a tank in the roof going down to the kitchen in a 2 storey house?) I know before the work was done if you had the bath taps on the cold water tap in the basin upstairs would not work!! It does now! Very strange!
 
There's nothing wrong with drinking water that came via the Storage tank as long as the tank is (was) reasonably clean.
All the water comes into the house through the same pipe it just takes a bit longer to get to the tap if it goes via the tank.
 
Oh okay, thanks. So if the supply was from the tank where he tested it would probably be low as relying on gravity? Am just thinking that as the pressure was good it is more likely to be a mains supply. (although I don't know what pressure water can get up to from a tank in the roof going down to the kitchen in a 2 storey house?) I know before the work was done if you had the bath taps on the cold water tap in the basin upstairs would not work!! It does now! Very strange!

No, what I meant was testing pressure will always remain constant, even if stopcock was only turned on slightly. I would think, given that the pressure tested okay previously, then it must have been all mains at sink and stopcock or other valve at sink was turned down creating poor flow.
 

Official Sponsors of Plumbers Talk

Similar plumbing topics

V
Replies
1
Views
962
Bathroom Advice
Deleted member 120897
D

We recommend City Plumbing Supplies, BES, and Plumbing Superstore for all plumbing supplies.