FRESH water supplies in Tuen Mun should be back to normal by 6 am today, Director of Water Supplies Hu Man-shiu announced last night, after frantic work to repair pumps damaged in floods on Friday. But the design of every water pumping station in the territory is to be reviewed following the breakdown, which left 420,000 people in Tuen Mun without fresh water. All 150 stations will be inspected to determine whether they need flood barriers such as walls, ditches, raised platforms or emergency drainage systems. Engineers from the Water Supplies Department are adamant there is no need to redesign pumping stations' electrically-powered motors - although they are not waterproof and break down as soon as they come into contact with water. ''We will look into the design of the stations to ensure water is kept away from the pumps, rather than the design of the motors themselves,'' said Tse Min-tat, the senior engineer in charge of customer relations at the Water Supplies Department. Mr Tse said any attempt to seal the motors - which would require steel cases and rubber gaskets - would cause them to overheat. The department has had almost 300 people - engineers, electricians and labourers - working around the clock to repair pumps at Tuen Mun's water treatment plant. Flooding during Severe Tropical Storm Ira on Friday inundated the station at Fu Tei, swamping its six main electric pumps and two auxiliary diesel pumps. Mr Tse said the Tuen Mun pumping station already had flood prevention measures, such as a raised platform around the pump pit. ''But the design of the plant did not anticipate the sudden rush of water we had on Friday,'' he said. ''All the stations in Hong Kong have preventative measures which estimate the maximum amount of flooding with regard to rainfall figures and nearby topography. ''But these might need to be revised because the natural drainage systems in Hong Kong have changed rapidly in the last few years.'' He said people had illegally blocked natural drainage routes, and these would need to be investigated to see whether pumping stations could cope with the change. Mr Tse said possible prevention measures at pumping stations include: Installing emergency pumps at the bottom of pits which drain water as it flows in. Shifting pumps to higher levels. Installing flood barriers such as walls, ditches and drains. Acting Governor Sir David Ford visited the pumping station yesterday to get a first-hand look at the repair work. After inspecting the station, Sir David visited one of the water tankers based on Tuen Mun's Butterfly Estate, where he said he appreciated the patience and co-operation of residents. ''I'd like to pay a tribute to the people in Tuen Mun who have had a very difficult situation to live in over the past two days,'' he said. He also thanked the government departments involved in the work.