Leaking bottom fill on toilet cistern

[Dave Thornley]

Just fitted a new WC all ok except for a leaking bottom fill connection. It is a Fluidmaster fill valve usual 1/2 inch connector. The leak occurs from between the base of the cistern and the plastic nut, not between the nut and the thread of the valve. It was supplied with a flat washer to be positioned inside the cistern but does not seem to do much of a job.

 

[mikeyd]

I'll ask for this to be moved to the plumbing forum. If the leak is from water already in the cistern rather than water entering the fill valve then the 'flat washer' might not be seated correctly. But I am just a DIY type and wouldn't know where to go from there, without seeing the bigger picture. Some photos might be useful.

 

[mattylad]

Is it a flat rubber washer?
Have you tightened it too much, thus deforming it?
Is there a bit of grit underneath it?

Empty the cistern, undo it and reseat it.

 

[undertrained]

Have you tightened it up enough? These rarely leak that I know of, could be foreign matter eg grit, etc as Mattylad has said.

 

[Madrab]

All standard fluidmaster valves come with a cone shaped rubber seal, the flat end sits inside on the fill valve shoulder and the cone end should be sitting into the hole. I'd check that first. If that's all ok then it may need more of a tighten. If it still doesn't work then there's something wrong with either the seal or the cistern, as a last resort a little silicone on the washer, both sides before fitting into a dry cistern and don't overtighten.