LONDON (Reuters) - Toilet seats are more hygienic than many surfaces in the average home, including chopping boards, kitchen surfaces and sinks, according to a report on Wednesday. A survey of 15 homes by researchers from the University of Arizona in Tucson found the toilet seat was the cleanest of 14 sites in kitchens and toilets. During the 30-week study the researchers took samples of bacteria from each site. In the final 10 weeks they gave the homeowners bleach and told them how to keep the surfaces clean. "What we found, and we are still theorising as to why, is that even before we introduced any disinfectant, the toilet seat was always the cleanest site," Pat Rusin, who led the study, told New Scientist magazine. Kitchen chopping boards had three times as many bacteria as the toilet seat and water rung from dishcloths had a million times more. The researchers think bacteria breed better in damp environments such as chopping boards and kitchen surfaces and cannot thrive on toilet seats which are too dry. They advised homeowners to soak dishcloths in a sink filled with a cup of bleach for at least 10 minutes once a week and said kitchen worktops should be scrubbed daily.