For years I've been keeping my sink and bath plugholes and overflows clean and clear by putting in a bit of bleach for a few hours or overnight before cleaning the bathroom. Recently I read somewhere that bleach can damage pipes and now I'm worried that I've been destroying my pipes all these years! What's the truth? Is it okay to use bleach, or is there another, better way to keep the drains clean and clear? I'm not talking about unblocking or dealing with a problem - just regular, preventive maintenance.