Compared with the grading released last week, Kiu Tsui Beach, Middle Bay Beach and Shek O Beach have been upgraded from 'fair' to 'good' ; Butterfly Beach was upgraded from 'poor' to 'fair' and Lower Cheung Sha Beach was downgraded from 'good' to 'fair'.

The department said the changes in grading are generally within the normal range of fluctuation of the bacteriological water quality of the beaches.

Seven gazetted beaches - Anglers' Beach, Approach Beach, Ting Kau Beach, Casam Beach, Gemini Beaches, Hoi Mei Wan Beach and Lido Beach - are closed to swimmers year round because of poor water quality.

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