Water quality at 13 beaches has been rated 'good' for this weekend, 14 'fair' and six 'poor', while Butterfly Beach, Castle Peak Beach and Kadoorie Beach have been downgraded to 'poor', according to the Environmental Protection Department's latest grading.

Compared to last week, Pui O Beach and Stanley Main Beach have been upgraded from fair to good, Ma Wan Tung Wan Beach and St Stephen's Beach have been upgraded from very poor to poor, and Butterfly Beach, Castle Peak Beach and Kadoorie Beach have been changed from fair to poor.

The department said the poor water quality of Butterfly Beach, Castle Peak Beach and Kadoorie Beach is due to heavy rain which flushed pollutants from their nearby areas into the water, while changes in other beaches are generally within the normal range of fluctuation of the bacteriological water quality.

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

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

See the department's website or call 2511 6666 for more information.