Tap washer issues

[DKL]

Our kitchen tap was dripping just before Christmas. It's a fairly traditional farmhouse mixer tap, we've had it number of years and it has been fine until then. Didn't seem unreasonable so I found a box of tap washers and changed them both.
All was fine for a few weeks but gradually the drip came back. Fished both out again today and there are deep grooves in the washers from tightening the heads during use I imagine. I noticed, and had initially on reflection, that the 3/8" washer didn't fill the holder for the washer very well, it was a bit loose but a 1/2" washer was too big. I found another set of glands and the washers fit snuggly into the holder.
I'm aware it could be the mating face for the washer in the tap unit but it seems unlikely so why is it leaking again so soon?
I suppose I could change both glands but it should be a quick and easy fix to stop a leak.
Any ideas?

[LooneyTunes]

You could try reseating the tap or using a domed tap washer.

[Bill]

DKL said:

I'm aware it could be the mating face for the washer in the tap unit but it seems unlikely so why is it leaking again so soon?

This would be my guess, grinding the seat is an easy job.

[mcdjl]

Not all tap washers are equal. I going some 1/2" to be smaller than 3/8" and vice versa. I gave up trying to find the right size for mine and replaced the taps entirely.

[wolfracesonic]

LooneyTunes said:

You could try reseating the tap or using a domed tap washer.

I had exactly the same issue, re-seating was the root cause/ solution I think but I took a punt on some domed washers, problem solved! I naively went to a Grahams plumbers merchant 10 minutes from me…’No we don’t have those, try B&Q’

[DKL]

Hmm, ok thanks. I have domed washers so could try that. I think I have a grinding tool too so work for the weekend.