HONG Kong will review its billion-dollar commitment to buy two-thirds of the territory's water supply from China after heavy rains from Typhoon Dot have swelled reservoirs. Figures released yesterday show Hong Kong's reservoirs stand at 90.6 per cent capacity, or 530.737 million cubic metres. The Water Supplies Department said yesterday 14 of its 17 water storage containers had reached capacity and excess water was now spilling out to sea. This follows the downpour that accompanied Typhoon Dot when 454 millimetres of rain fell, according to the Royal Observatory. This year, the total rainfall for September stands at 655 mm, well ahead of last year when for the equivalent period only 61.9 mm had fallen. The year before it was 176.6 mm. Department officials said they would review this year's deal to buy $1.11 billion - 630 million cubic metres - worth of water from China. Tse Min-tat, the department's senior engineer, said the commitment was revised last year after an abnormally wet season. ''We will review the commitment again and might decide to defer some of this year's amount,'' Mr Tse said. ''Last year we reached a similar agreement to defer some of the originally agreed quantity because of unusually high rainfall.'' He said they would consider striking a deal similar to one made last year when no water was bought from China during November and December - which saved about $200 million. In September last year, there was a 15 per cent cut in water from China, reducing the normal daily supply from two million cubic metres to 1.7 million cubic metres. All of the catchments are now full except the three largest: the Plover Cove Reservoir, the High Island Reservoir and the Lower Shing Mun Reservoir. The other catchments have been automatically flushing excess water out to sea. Mr Tse said it was impossible to calculate how much water had been wasted and that it would be difficult to redirect it elsewhere. He said only a few of the modern reservoirs were able to redirect water into others when they became full. Many of the other dams were built in the 1940s and did not have such a facility. ''Because of geographical and technical restraints it is difficult for us to revise our overflow arrangements,'' he said. All the catchments had a built-in overflow so that nearby areas could not be saturated. Yesterday's floods saw the postponement of a meeting to discuss increasing water pollution penalties. The Legislative Council bills committee was due to begin scrutinising the Water Pollution Control (Amendment) Bill 1992 at 8:30 am. But only committee chairman Christine Loh Kung-wai had arrived by 8.45 am and she postponed the meeting. Other members due to attend were Tang Siu-tong, Samuel Wong Ping-wai and Albert Chan Wai-yip.