Water quality at 28 beaches has been rated "good" for this weekend and five "fair", according to the Environmental Protection Department's latest grading.

Compared with last week's grading, Kadoorie Beach has been upgraded from "fair" to "good", while Butterfly Beach, Cafeteria New Beach, and Kiu Tsui Beach have downgraded, from "good" to "fair".

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

Seven gazetted beaches - 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 suggested during and after periods of heavy rain, bathers are advised to avoid swimming at beaches for up to three days after a storm or heavy rainfall.