Cistern very slow to refill

[ScotHill]

The occasional toilet in the cupboard under the stairs takes a long time to refill, feels like ten minutes sometimes. The flow to the sink is fine so assuming it’s not the pipework, what else can I check before calling a plumber?

Is there anything that I can try draining and replacing myself?

[Mr Pointy]

There's a few possibilites:

1) An issue with the supply - isolating valve is small bore type or not fully open, or maybe flexi hose is kinked if there is one.
2) The inlet valve is a high pressure type & you have a low pressure supply
3) the inlet valve is blocked with scale or debris.

It looks like twisting the blue part will release the fill valve so you can check it but isolate the water supply first.

[ScotHill]

Will have a look thanks.

To clarify it never used to be like this, although I don’t know how quickly/gradually it got worse.

[p4cks]

Inside the blue screw thing there's likely to be a rubber diaphragm (similar to the below) that will have split, which can cause slow refill speed. I'd check that too, and get some spares as they are awful quality and they go quite often.

[ScotHill]

Is that a rubber ball valve washer? Are they standard sizes?

[Mr Pointy]

ScotHill said:

Is that a rubber ball valve washer? Are they standard sizes?

No, they tend to be manufacturer specific so you'll need to identify the brand of fill valve.

[spikeyhead]

Has it always been slow to fill, if so I'd be checking the feed to the cistern and making sure the tap is fully open

[petrolbloke]

OP said it hasn't always been slow to refill.

It's probably the fill valve. I've recently had to replace two in my house (plus the flush valves/siphons). Quite straightforward to DIY, plenty of YouTube videos to help. Main thing is don't under or over tighten fittings to avoid getting any leaks. If you have a bit of flexible hose (e.g. old garden hose) then you can use that to siphon 99% of the water out of the cistern.

[The Gauge]

I had the same problem with mine and fixed it recently by changing the rubber diaphragm in the filler unit. Lots of videos on Youtube to assist you. Although mine is a different model of flush unit my thread might assist you..

https://www.pistonheads.com/gassing/topic.asp?h=0&...

[netherfield]

If you undo the Blue collar at the top there might be a plastic cone behind it, this can have a small hole where the water comes through, they sometimes get blocked.if i have a spare i'll take some photos.

[netherfield]

Could be this little hole getting blocked.

[netherfield]

Better picture

[Ashtray83]

opella torbeck diaphragm washer simple job, isolate water undo the blue nut and swap it out. They split and stop them opening fully