Kitchen mixer tap – Cold water will not turn off

Mr M · 5 Oct 2025

My Kitchen mixer tap has been dripping for a while now, so I thought I would remove both brass screw-in glands to check the washers in each and give the glands a clean at the same time. I did this and both glands looked in reasonable condition. I also checked both while I had them removed, to make sure they were turning to the on and the off positions which they were, so I re-fitted both glands back into the tap.

I have ball-o-fix valves on both the hot and cold water supplies to the tap. When I turned the cold water supply back on, water started running from the tap head so I assumed I had reinstated the gland with it in the ‘tap on’ position. When I moved the tap on/off lever to its opposite way, the cold water continued to run. I turned the tap on/off lever fully both ways but the cold water continued running.

The hot water supply was fine after its gland had been re-fitted so I thought I would swap the glands over to check if the hot water would then continuously run and if the cold water would turn on and off. In other words, to try to rule out if one of the glands was now faulty.

I swapped the glands over but it was exactly the same. The cold water ran continuously regardless of whether the tap on/off lever was switched fully on or fully off and the hot tap worked as it should which suggests to me that the glands are working as they should?

Can anyone shed any light on what is causing the above to happen to the cold water side of my Kitchen mixer tap?

Thanks in advance for any responses received.

Wayners · 5 Oct 2025

The rubber seat may have corroded. You can buy a reseating tool to grind it smooth again but I've tried on old taps and found it failed. Just buy a new tap if that's your problem. Look and feel where rubber seals for damage

Mr M · 5 Oct 2025

Wayners said:
The rubber seat may have corroded.

Thanks for your quick reply. Where is the rubber seat that you refer to, located please?

Also, after having described how I have tested the glands, am I correct that they do not appear to be defective? It's definitely the complete tap that needs replacing?

Wayners · 5 Oct 2025

Is it a ceramic ¼ turn or the older rubber washer?
Could also be a cartridge.

If a cartridge or ceramic you need replace it. Sometimes ceramic fix themselves with a wash but often not...

Put up a picture may help

Mr M · 5 Oct 2025

It's the 1/4 turn brass type

When I turn the head on the gland, I can see the insert inside the gland moving from the open to the closed position and vice versa.

Also, when I blow into the gland when it's in the open position, the air comes through it. When I blow into it in the closed position, absolutely no air comes through it.

I've tried to photograph it in the open and closed positions but you can't really see this on the photos but the gland does seem to be working as it should and as I say, I swapped the glands over and the other gland that was working as it should in the hot side of the tap, didn't turn the water off on the cold side of the tap.

avonmouth · 5 Oct 2025

You can buy this kit on ebay for £3.15..........https://www.ebay.co.uk/itm/404258887855
It will fit tour tap and is an easy job.

accelerator · 5 Oct 2025

Mr M said:
I've tried to photograph it in the open and closed positions but you can't really see this on the photos but the gland does seem to be working as it should and as I say, I swapped the glands over and the other gland that was working as it should in the hot side of the tap, didn't turn the water off on the cold side of the tap.

This suggests that on the cold side, a gland cannot turn the water supply off because there is damage in the tap seat, i.e. water can get through even when the tap is properly closed. Can you see any damage within the tap on the cold side that could be causing this?

Mr M · 5 Oct 2025

I can't see any obvious signs of damage within the tap but I am not 100% sure what type of damage I'm looking for. I don't know if you can tell if there's damage, from the photos below.

Alec_t · 5 Oct 2025

Try a thinnner O-ring/ rubber washer on the cartridge, so that the blue seal can press fully against the valve seat.

Mr M · 5 Oct 2025

Alec_t said:
Try a thinnner O-ring/ rubber washer on the cartridge, so that the blue seal can press fully against the valve seat.

Apologies but I am not familiar with some of the plumbing terminology.

Is the cartridge that you refer to the same thing that I am calling the gland? ie the brass unit that screws into the tap itself that I have pictured below.

Also, where is the 'valve seat' located?

Is it the black O-ring/rubber washer that is shown (mid-way down the gland) in the above photo what you are suggesting I should replace with a thinner one or is it somewhere else?

I haven't got any replacement thinner O-ring/rubber washers here now but if it is that that you are referring to, could I simply remove the existing O-ring/rubber altogether and then re-fit the gland in the tap to test what you have suggested? I appreciate this is not ideal and that the gland may weep but it would only be temporary to try to do what you have suggested.

avonmouth · 5 Oct 2025

Buy this kit on ebay for £3.
It will fit your tap.

Mr M · 5 Oct 2025

Ok, so I removed the O-ring/rubber washer altogether from the gland and I checked that the gland was in the closed position before refitting it into the cold water side of the tap. Removing the O-ring/rubber washer from the gland should mean that when it is screwed in, the gland sits slightly further into the tap body than it did before, effectively meaning that the blue seal at the end of the gland has a better chance of closing-up against the inside of the tap to create a seal against the hole inside the tap (The hole that is shown in the photo below).

I then turned the cold water supply back on via the ball-o-fix valve and water started running from the tap head. I moved the tap on/off lever to its opposite way but it made no difference, so removing the O-ring/rubber washer didn’t work.

I then reduced the cold water supply flow through the tap by turning the ball-o-fix valve and I unscrewed the gland from the tap body and removed it. Water was then obviously coming out of the opening in the tap where the gland screws into. I put my finger inside the tap to fully seal the hole inside the tap that can be seen in the photo above and no water water flowed out of the tap head (as though I had turned the tap off). When I took my finger off the hole inside the tap, water started flowing again from the opening in the tap where the gland screws into.

It appears as though for whatever reason, neither of the existing glands that I have tried are properly sealing the hole in the tap body on the cold side.

Is there anything else that I can try?

Alec_t · 5 Oct 2025

Mr M said:
Is the cartridge that you refer to the same thing that I am calling the gland? ie the brass unit that screws into the tap itself that I have pictured below.

Also, where is the 'valve seat' located?

Cartridge=gland.
The O-ring is halfway down the gland.
The valve seat is in the tap housing and shown in post #11.

accelerator · 5 Oct 2025

accelerator said:
This suggests that on the cold side, a gland cannot turn the water supply off because there is damage in the tap seat, i.e. water can get through even when the tap is properly closed. Can you see any damage within the tap on the cold side that could be causing this?

I've thought about this a bit more and your test of swapping the hot cartridge into the cold side is not valid, because the cartridges are handed, that's why you need specific cartridges for hot and cold, so they can both open by moving the tap the same way (when they're on different sides).

Mr M · 5 Oct 2025

Alec_t said:
Cartridge=gland.
The O-ring is halfway down the gland.
The valve seat is in the tap housing and shown in post #11.

Understood. Thanks for clarifying.

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Kitchen mixer tap – Cold water will not turn off

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