Easain

@markc thanks, I think this will be my next thing to try yes . had wondered if there was anything thicker then ptfe tape I could try? after connecting everything I realised I didn’t leave enough room between the roof to fit the uv bulb in so need to dismantle and re jig it all anyway ?

@Cpd I presumed everything was a parallel thread as there didn’t seem to be other option for connections - I seems that all my threaded connections are seeping even when plastic/plastic or plastic/metal.

I’m building a uv water treatment and break tank with pump in an outbuilding as we are on private supply. I cannot get these joints to seal with lots of ptfe tape. I have seen others on the forum use these joints so I presume it would work. Any advice appreciated .