I have a leak from where the pipe from the toilet cistern joins the pipe which goes through the wall and outside. The one plastic pipe is just pushed into the other one. I realise that as a separate issue I have to address the level of water in the cistern - I know it shouldn't be high enough to go into the pipe. But in the first instance how do I make this connection water tight. As I say it is just one pipe slotted into another seems a bit primitive to me (as a mere female OAP) but it has been fine for the 18 years since it was first plumbed in. If anyone can help me and explain simply I should be grateful. Thanks for reading this.

Pilgrim, February 2014

Thank you very much Bob and Rich T for your clear and helpful answers. I will do as you say and try the sealant in the short term but also do some research on getting a new syphon unit.

Thanks again.

Pilgrim, March 2014

What you are probably seeing is not a pipe slotted into another but the overflow pipe joint socket which does give that appearance as to sealing go with Rich t as that would be my answer without removing and refixing. Normally these joints are soldered with plumbers Solvent glue. But sealant should work also.
I suspect its an old unit as most nowadays the overflow is built into the cistern so runs in to the toilet pan instead of on the floor. I would be worth getting the syphone unit changed as well and the water inlet valve as the washer may have worn and still allowing water through. You can do a search on the internet to see how various types of work. Type in the search engine 'Types of cistern syphon's and how they work'.

Bob, March 2014

Buy a tube of Silicone sealant from any DIY store and slap it liberally around the joint and job done, good luck.

Rich t, February 2014