Plumbing help!

[Auntieobem]

Our downstairs loo is leaking from the cistern where the overflow pipe leaves the cistern at the base. I've googled, but just find lots of info re fixing ballcocks and stopping toilet overflowing. I'm assuming that a seal has gone - but apart from that am clueless. @pigletjohn any ideas???

For most connections through ceramic items there’s a rubber washer on the inside which is compressed to give a seal by tightening a nut on the outside. Can you see a nut which is tight to the cistern like this?

If so, try gently tightening it?

For a bad leak you’ll need to cut the water supply in, possibly by turning an inline tap (rarely present!) or just tying up the ballcock if there is one. Then you can flush the bulk of the water away and sponge out the remainder.

Once the cistern is dry you can disassemble the relevant parts. Buy a few rubber washers to keep as spares.

We've already tied up the ballcock (grateful for more than 1 loo) Don't think anything is loose, have ordered some plumbers putty as emergency fix

is it a plastic pipe with a plastic washer?

you can give it a quarter turn with a big wrench

if the rubber washer has perished you will need to unscrew it and fit a new one

How old is it?

Cistern blocks containing bleach can make them perish faster.

More modern flush valves incorprate an overflow pipe that runs into the pan, so the overflow in the cistern can be capped off.

I don't know the washer size without looking. Might be 22mm. But you can buy
a new pipe including washer very cheaply.

Thanks @PigletJohn , got someone coming to look tomorrow...