In article ,
Tim S wrote:

b) Over tightening. Do the nut finger tight, then about one turn with a
spanner. It's better to err of being undertight, because you can tighten
more. Over-tight and the olive is bent. Turn the water on and look for
weeping joints, tighten gently until they don't. Eventutally you get a
knack of how tight to do them in the first place.

Ta for all the replies. I couldn't see how PTFE would
help either. The pipes are new, spotlessly clean, cut
absolutely square, and the joints aligned well.

I'd not appreciated that it was possible to over-tighten
them -- looks like that might be where I've gone wrong
with some of them. Time to dis-assemble and try being
less enthusiastic with the spanner this time!

Thanks again.

G.