The Environmental Protection Department has rated water quality at 23 beaches 'good', nine 'fair' and one 'poor' for this weekend.

Compared with last week's gradings, Kiu Tsui Beach and Shek O Beach have been upgraded from 'fair' to 'good', while Ma Wan Tung Wan Beach has been downgraded from 'fair' to 'poor'.

As many beaches are likely to be more polluted than their grades suggest during and after periods of heavy rain, bathers should avoid swimming for up to three days after a storm or heavy rainfall.

Seven beaches - Anglers', Approach, Ting Kau, Casam, Gemini, Hoi Mei Wan and Lido - are closed to swimmers year round because of poor water quality. The public is advised not to swim at these closed beaches.

Under the grading system, beaches are classified into four grades according to the level of E.coli in the water.