Macau's drinking water has become so salty that its supply might be switched from Guangdong's West River to the North River, itself heavily polluted this month by a leak of toxic cadmium. The salt content of Macau's water has doubled as salt tides continue to plague Pearl River Delta watercourses including the Xijiang, or West River, amid a persistent drought. The biggest salt tide for six years is expected on Monday. Guangdong authorities have proposed switching the source of supply to the Beijiang, or North River, said Franklin Willemyns, executive director of the monopoly Macau Water Supply Company. 'There's a plan to draw water from the Feilaixia reservoir [on the upper reaches of the Beijiang],' Mr Willemyns said. 'But we don't know when that will happen, how much water we will get, or whether they are really going to do it.' A smelting plant spilled more than 1,000 tonnes of materials highly contaminated with cadmium into the Beijiang on December 16, forcing the use of alternative supplies. Mr Willemyns said the contamination should have been resolved by the time any switch was made. Macau draws almost all its daily consumption of 160 million litres from the Xijiang. The salt content of the water has risen from 250mg per litre to 500mg. Mainland officials have warned the situation may worsen in the next one or two months. Water rationing was imposed in Zhuhai , the city hardest hit by the salt tides, on Monday. In Hong Kong, a spokeswoman for the Water Supplies Department said local water quality would not be affected since supplies came from the Dongjiang, or East River.