DIY Doctor UK DIY Forums

The ceramic cistern for my toilet has a crack in it (sorry, tried to attach a photo but it was rejected as too large: the crack is from the hole that the down pipe to the toilet bowl goes into and it's a couple of inches long.) Previously I've mended it with No Nonsense clear silicone applied from the outside edges of the rubber seal washer to beyond the end of the crack and it's lasted about three years, but it's now leaking again. I've now removed the old silicone as best I can and I'm going to try sealing it again.

My question is: Is there anything that would work better than silicone sealant (e.g. plumber's mait)? Thanks.

Hi zacccc
Since you have used silicone in the past it's better you stick with the same.
Regards S

Thanks for your reply but before I'd received it I'd already bought and used some CT1 sealant, which isn't silicone based but which I'd been told was better than silicone sealant. I'm just waiting for it to cure. It was £12 from Wickes, so it better work!

stoneyboy wrote:Hi zacccc
Since you have used silicone in the past it's better you stick with the same.
Regards S

Hi stoneyboy,

As I said in my last post, before reading your post I'd already had a reply from someone on another forum. By mistake, in my original post I gave the wrong information. I said that my cistern was ceramic. I don't know what I was thinking of when I said that! It's not ceramic ... it's plastic! Anyway, I didn't realize my mistake until I'd bought some CT1 and applied it. Unfortunately, it hasn't worked, even though I've had three goes at it, each time applying more CT1 not only inside the cistern but also round the pipe coming out of the cistern to the toilet bowl. But I've still got a very slight leak, so now I'm thinking that perhaps CT1, while suitable for a ceramic repair, isn't the right stuff for repairing a plastic cistern. Do you know if I'm right about this? If so, what I'm intending to do is apply a silicon sealant at the edges of the CT1 sealant that's already there and see if that works. I'd welcome any advice on this. Thanks.