Please help me diagnose a problem with my cold water pressure/kitchen sink

Doug Cartel

Hi, About two weeks ago the amount of water coming out of in the cold tap in my kitchen sink suddenly dropped by a quite noticeable amount. It stayed like that for a week, and now after an additional week away at my parents, I've come home to find it's producing the tiniest trickle of water.

The water flow in every other tap in the house is absolutely fine, hot and cold. If I turn the cold tap in the kitchen with my thumb over the opening, the pressure is actually quite high - higher than in the hot water which is flowing fine.

I have no idea about plumbing, but my guess is that there's some air trapped in the cold water pipes for the kitchen. Does this sound about right? Is it something fixable, or do I need a plumber?

Prenderb

Cold tap in the kitchen sink is usually directly off the mains - if you have mains water that is. If the pressure in that cold tap is low, that suggests that either there's a pressure problem in the mains (check with neighbours or the council/group scheme) or that the recent cold weather has partially frozen your feed, thus restricting the flow.

steamengine

Doug Cartel wrote: »

Hi, About two weeks ago the amount of water coming out of in the cold tap in my kitchen sink suddenly dropped by a quite noticeable amount. It stayed like that for a week, and now after an additional week away at my parents, I've come home to find it's producing the tiniest trickle of water.

The water flow in every other tap in the house is absolutely fine, hot and cold. If I turn the cold tap in the kitchen with my thumb over the opening, the pressure is actually quite high - higher than in the hot water which is flowing fine.

I have no idea about plumbing, but my guess is that there's some air trapped in the cold water pipes for the kitchen. Does this sound about right? Is it something fixable, or do I need a plumber?

Check first its not a freezing problem. Check with your neighbours to see if they're affected.

Assuming its not then it sounds like there is something broken inside eg fractured spindle. Common fault, most kitchen taps can be repaired depending on your DIY skill. The trick is to open the valve body up with out twisting the tap around and causing more damage. Two spanners or wrenches must be used, so as to ensure the valve body does not rotate. After that repair kits or internal valve assemblies are available in most good plumbers supplies or Woodies, B&Q etc. Bring the old part with you. ps !!! don't forget to turn off the water first !!!

Prenderb

Actually, yeah, I hadn't thought of the tap being an issue too!

Doug Cartel

I have a question or two about pressure. If there's freezing or any other blockage, will that cause the total pressure in the tap to drop or just the water? I ask because while there's only a bit of water coming out, there is clearly a lot more air pressure in the cold tap then in the warm water one - eg, I can just about stop the flow by holding my finger over the opening when the cold is turned on, but with the hot water on it is very easy to stop.

Also, if there is a block in the mains, shouldn't I have seen a drop in the hot water. It's been two weeks since the cold water changed, and we were using the hot water regularly for about a week after that no problems. Would you expect there to be a drop in the hot water, or could there be enough trickling into the tank for me not to notice?

Like I said it's only that one tap, every other one - both hot and cold - is working fine.

Doug Cartel

steamengine wrote: »

Check first its not a freezing problem. Check with your neighbours to see if they're affected.

I think the problem started before the really cold weather came in. I'll ask the neighbours in the morning though.

steamengine

Doug Cartel wrote: »

I have a question or two about pressure. If there's freezing or any other blockage, will that cause the total pressure in the tap to drop or just the water? I ask because while there's only a bit of water coming out, there is clearly a lot more air pressure in the cold tap then in the warm water one - eg, I can just about stop the flow by holding my finger over the opening when the cold is turned on, but with the hot water on it is very easy to stop.

Also, if there is a block in the mains, shouldn't I have seen a drop in the hot water. It's been two weeks since the cold water changed, and we were using the hot water regularly for about a week after that no problems. Would you expect there to be a drop in the hot water, or could there be enough trickling into the tank for me not to notice?

Like I said it's only that one tap, every other one - both hot and cold - is working fine.

That figures - you seem to have sufficient pressure - the flow is restricted. This could be due to partially frozen supply or a fault in the tap. the kitchen cold tap is usually the only mains tap. The other taps are supplied from the attic tank and that would supply the other hot and cold taps as long as there's water in it.

If the attic tank is accessible depress the ball cock down and check the flow to top up the tank - this is also mains.

steamengine

Doug Cartel wrote: »

I think the problem started before the really cold weather came in. I'll ask the neighbours in the morning though.

This weather is throwing an extra spanner in the works. However if you can depress the ball cock in the attic tank and it is also a restricted flow then it looks like a freezing problem. In this case keep a trickle of water flowing from say a bath tap - it may help the situation.

Prenderb

Doug Cartel wrote: »

I have a question or two about pressure. If there's freezing or any other blockage, will that cause the total pressure in the tap to drop or just the water? I ask because while there's only a bit of water coming out, there is clearly a lot more air pressure in the cold tap then in the warm water one - eg, I can just about stop the flow by holding my finger over the opening when the cold is turned on, but with the hot water on it is very easy to stop.

Also, if there is a block in the mains, shouldn't I have seen a drop in the hot water. It's been two weeks since the cold water changed, and we were using the hot water regularly for about a week after that no problems. Would you expect there to be a drop in the hot water, or could there be enough trickling into the tank for me not to notice?

Like I said it's only that one tap, every other one - both hot and cold - is working fine.

Usually there's good pressure in the cold tap because it comes from either a pumped supply or somewhere a good bit higher than you, maybe 20m higher if not moreso. Your hot tank and the cold tank for other cold taps are usually only 2.5m (in a bungalow) or 5 or so metres (in 2 storey)higher than the tap, hence the dramatic pressure difference.

Don't confuse pressure and flow rate...Pressure is the "force" of the water exiting the tap, flow is the amount that comes through. Little flow can have lots of pressure but you mightn't notice it as much when trying the "hand on tap" experiment, simply because there isn't as much water to exert that pressure on your hand!

The mains feed in your house separates - one part goes to the cold side of your kitchen tap and another spur is taken to your attic tank. The attic tank fills up whenever water is used up by flushing the loo, running a shower or other tap/appliance. It would be fair to say that this could fill back up slowly after a flush but you mightn't notice if it was taking 50% longer than previously. The attic tank usually has a capacity of at least 1000l, and a flush could be 5 to 9, so you probably wouldn't notice if the refill from something like a flush was slower. Forgive me if I'm teaching you to suck eggs, I mean to be helpful not patronising!

Similarly, all hot water in your house would originate from the attic tank via the hot water cylinder in the hot press, so as long as there is something coming through up there to keep the tank topped off you wouldn't notice.

Doug Cartel

Thanks for the help everyone. I'll wait till the morning to check with the neighbours and have a poke in the attic.

It's kind of funny though. I used to work as a physics researcher, but when it came down to it, I got flow rate and pressure mixed up.

vincenzo1975

if water was leaking somewhere then the pressure would drop as well. the fact that the water is still in the attic tank measn you could have a leak up there, check the overflow pipe from the attic tank to see if the ballcock is passing, then check the ball cock is operating OK. If you rule that out, check to see if you have water supply to your washing machine dishwasher as these will also be off the mains. If the supplyu there is OK, and no sign of leakage around them, then it is more then likely the tap is damaged.

before you go working on the tap, ensure you shut off the mains supply, normally located behind the press under the sink or around that area.do not get yourself into a situation where water is spraying out and you dont know where to turn it off.

steamengine

Doug Cartel wrote: »

Thanks for the help everyone. I'll wait till the morning to check with the neighbours and have a poke in the attic.

It's kind of funny though. I used to work as a physics researcher, but when it came down to it, I got flow rate and pressure mixed up.

Used the thumb over the kitchen tap trick myself - Tells you instantly if your mains water pressure exceeds your tank pressure, which in your case in does. In the absence of a pressure gauge !!! "Needs Must" !!!

items

Doug Cartel wrote: »

Hi, About two weeks ago the amount of water coming out of in the cold tap in my kitchen sink suddenly dropped by a quite noticeable amount. It stayed like that for a week, and now after an additional week away at my parents, I've come home to find it's producing the tiniest trickle of water.

The water flow in every other tap in the house is absolutely fine, hot and cold. If I turn the cold tap in the kitchen with my thumb over the opening, the pressure is actually quite high - higher than in the hot water which is flowing fine.

I have no idea about plumbing, but my guess is that there's some air trapped in the cold water pipes for the kitchen. Does this sound about right? Is it something fixable, or do I need a plumber?

Good few replies on this one, haven't really go over them all.

Just on taps, kitchen sink taps are used most in house, they do wear down, they don't last for ever. I've seen many cases where tap is fine, just the head of tap is wore down, inside tap head is a section with splines, these splines match up with spindle on tap body, over the years the splines wear down so while you turn your not really opening tap, its just catching in places.

Tap internals can also wear down causing restriction also build up with limescale restricting flow. Most common taps can have internals replaced, not a big job so not a big cost. Replace hot side at same time, when one goes, the other will go soon after.