Kitchen waste to bottle gully, then off to foul / rainwater waste (or whatever its called). It's been in service since the house was built 24 years ago. Over xmas I noticed the water wasn't draining from the sink when the washing machine was emptying (it had done for many years prior), so thought it was blocked. I removed the Dip Tube, cleaned everything up, but found no issue. With no Dip Tube, I threw 5 x14 litres buckets of water down the sink, it cleared with no issue. I put the dip tube back, and it blocks after one bucket. Nothing has change for 20 odd year, so can anyone give me a clue about what the issue may be?
