Toilet cistern ball valve dripping already!

Yes, and certainly worth a try. You can dissolve off any scale with descaler or vinegar. It might be some grit from the mains.

You can get replacement diaphram washers for them too. Note that there are one or two tiny holes in the washer by design.

That's on the short side, but depends on usage.

Or a bit of crud coming in with the supply after works on the main or building work in your place that opens up the cold supply pipe work.

Yes, isolate first... B-) Examin the the washer where the nozzle sits and see if there is a moulding flash or something that is causing damamge.

You can get kits of replacement disphram washers etc rather than replace the whole assembly. A kit froma shed may well be comparable in price to whole new valve but it'll be a quicker and simpler job just swapping parts.

The OP linked to an ordinary plastic ball valve not an equilibrium valve.

Diaphragm washers for ordinary ball valves don't have holes, or at least the one I have doesn't...

That sort's not very clever at the best of times because the floatation force of the ball puts a big bending load on the vertical tube. Does yours have an adjustable screw to react this force against the cistern casing? If so, make sure it's correctly adjusted and also adjust the water level down a bit to give a bit more leeway before it overflows.

If you *do* replace it, don't do a like for like but use one of these instead.

I'm using the side entry versions which replaced the old fashioned ball float valves in the upstairs loo low level cistern and the attic hot water header tank.

Seems to be an exact match to the ones bought a few years ago from a B&Q shed.

I've already replaced the one in the loo on account it suddenly took to spraying the water out of the top cap after a year or so instead of via the down pointing outlet pipe and forcing the sideways spray into the lid join, resulting in drippage from the cistern.

The replacement did the same thing about a year later but I decided not to play the 'rental' game and used an aluminium foil pie tray to act as a shield. There doesn't seem to be an obvious reason for this sudden change in behaviour, nor any way to disassemble it for repair or maintenance. Aside from this oddity, it still functions perfectly fine as a fill level control valve.

I've still got the original as a spare. Does anyone know if they can be taken apart for repair or maintenance?

Weird looking thing... is the float the round black cylinder thingy, sliding up the pole, so to speak?

But worth considering, thanks.

Yes

They seem to work ok.