I use something like this ...

http://www.screwfix.com/search.do?fh_search=overflow%20waste%20pipe&cm_mmc =MSN-_-Plumbing%20|%20Drainage%20and%20Sewerage%20|%20Gen eric-_-Pipes%20-%20Overflows%20-%20Exact-_-overflow%20pipe

Two flanges to get the mastic/putty onto.

Mike



"'Mike'" wrote in message ...

We have 5 across the back of the garage and have had the same problem. I
took them all out again and gave the washers a good coating of mastick
inside and out. When nd if it leaks again, as long as it is only a small
leak, I find that the general crud seems to seal it up again.

Thanks for the lollipop ;-)

Mike



"Broadback" wrote in message ...

I have set up three rainwater butts, linked at the bottom. works quite
well but from time to time develops a leak in one joint or another. I
have been looking at larger storage tanks, but they seem ridiculously
expensive. Any suggestions?