Water quality at six beaches has been downgraded after heavy rain this week. Sixteen beaches were classified as good, down from 18 last week, and 21 the previous week, the Environmental Protection Department said. It warned that beaches were likely to be more polluted than their grades suggested after heavy rains. No beaches were closed due to red tide yesterday, but red flags have been hoisted at five Tuen Mun beaches since Thursday - Old and New Cafeteria, Kadoorie, Butterfly and Golden. The gradings of Cheung Sha Lower and Trio (Hebe Haven) have changed from fair to good; Hairpin, Shek O, Stanley Main and St Stephen's from good to fair; Lido and Old Cafeteria from fair to poor. Anglers, Approach, Ting Kau, Castle Peak and Rocky Bay are closed to swimmers because of unsuitable water quality or a lack of facilities. Good: Deep Water Bay, Kwun Yam Wan, Middle Bay, Tong Fuk, Repulse Bay, Lo So Shing, South Bay, Pui O, Turtle Cove, Clear Water Bay 2nd, Cheung Sha Upper and Lower, Hap Mun Bay, Kiu Tsui, Hung Shing Yeh, Trio (Hebe Haven). Fair: Big Wave Bay, Tung Wan (Cheung Chau), Chung Hom Kok, Clear Water Bay 1st, Hairpin, Silverstrand, Shek O, Tung Wan (Ma Wan), St Stephen's, New Cafeteria, Stanley Main, Kadoorie, Discovery Bay, Butterfly, Silvermine Bay. Poor: Casam, Lido, Gemini, Old Cafeteria, Hoi Mei Wan, Golden Beach.