What causes a blow back of water at the end of the flush when the last water has left the bowl? This happens on both of the toilets in the house.

JT, December 2008

I'm not a plumber but it sounds like you have a situation with your drains whereby 'stuff' can flow out of the bowl and down the drain - but not freely into the main sewer - hence the blowback. If this situation has developed recently I would suspect a partly blocked drain between your house and where it joins the sewer in the road. If you can lift any manhole covers you may learn something. I once found a complete house brick causing a blockage to a drain for six houses (ours was one!)

Richard, January 2009