Toilet Leak from Cistern

[1SJC]

Good evening,

We noticed a small pool of water around the base of our hidden cistern toilet. After some investigation, we found the leak to be coming from a seal around a connection between the toilet's back and the cistern.

I've tried unscrewing the part that connects the pipe to the cistern to clean and re-align, as well as a small amount of PTFE tape, but unfortunately, it's still leaking.

The 'seal' is made of hard plastic, and when inspected, I couldn't see any immediate cracks or faults, so I'm wondering whether it's likely to be a small micro-crack that I can't see or perhaps the cistern has developed a crack.

Could anyone suggest how to fix it and what I need to order? I'm wondering if a rubber doughnut ring might work and be the cheapest option - and failing that, I guess I might need to look at replacing the cistern.

Thanks for your help.
Joe

 

[Stuckinarut]

What’s the cistern material made from? A donut washer won’t cure it. It could just be the syphon tail washer, I’d replace that before doing much else.

https://www.amazon.co.uk/Toilet-Syphon-Outlet-Washer-41-50mm/dp/B072LRGMRM

 

[1SJC]

What’s the cistern material made from? A donut washer won’t cure it. It could just be the syphon washer, I’d replace that before doing much else.

Thanks, I wasn't sure of the correct terminology, but it appears that the syphon washer was what I was looking for.

The cistern is made of cheap, fairly-thin plastic.

 

[Stuckinarut]

Thanks, I wasn't sure of the correct terminology, but it appears that the syphon washer was what I was looking for.

The cistern is made of cheap, family-thin plastic.

I’ve just edited my reply post, with a link. Another thing to try might be adding some food dye to the cistern, which may show if there’s crack.

 

[1SJC]

I’ve just edited my reply post, with a link. Another thing to try might be adding some food dye to the cistern, which may show if there’s crack.

I appreciate that, thank you. Would something like this be the same: https://www.toolstation.com/syphon-tail-washer/p66356

I want to collect it tomorrow, if possible.

Failing that, I'll perhaps try your dye test to see whether that shows any cracks.

 

[Stuckinarut]

I appreciate that, thank you. Would something like this be the same: https://www.toolstation.com/syphon-tail-washer/p66356

Looks like the correct one, so should work. Could be 1.5” you need though.

 

[1SJC]

Looks like the correct one, so should work. Could be 1.5” you need though.

Thank you kindly for all your help. Going to take off the existing washer now to measure, will collect first thing and update tomorrow with some (hopefully good) news.

Thanks again.