I have a major problem with a leaking bath waste. I was recently called to a customers house as they had water dripping from there kitchen ceiling from the bathroom above. The main problem was a broken fibre washer on the hot tap but I also noticed that the bath waste was leaking slightly and so cleaned off all the silicone and fitted a new rubber sealing washer (without silicone). The next day they called to say the bath waste was still leaking so I went back and this time used silicone between the rubber seal and the bath. However, the next day they ca\lled to say it was still leaking ! I therefore installed a complete new waste and trap (without silicone) but again they called to say it was still leaking. I have since used both Plumbers Mate and Fernox LSX (on two different occasions) but still the customer calls to say it is still leaking. Every time I have been to the customer I have filled the bath half full of water, drained it down and not had a single leak. However, the customer has baths regularly and fills the bath to just below the overflow. When they have finished the bath, they drain it but sit in the bath while it drains. The bath does not leak when they have showers or when the bath is half full or less. I have now run out of ideas and so any advice would be much appreciated. Thank you.