At least 10,000 people in a South China town suffered a shortage of drinking water on Wednesday after excessive manganese was detected in their tap water.

The city government of Lufeng in Guangdong province said the manganese level in the tap water in Da'an town had been 1.2 mg per liter since Monday - 12 times the maximum permissible amount in drinking water.

The cause of the contamination remains under investigation and environmental specialists from Lufeng city were in town to conduct further tests, said Huang Xianjia, a city government spokesman.

Health officials say manganese is both a common chemical element and a required nutrient in drinking water. Nonetheless, excessive amounts of manganese can pose neurotoxic effects not limited to mental and behavioral disturbances, as well as impairment of motor skills.

The local government established emergency notices on every busy street in the city on Tuesday, warning residents not to drink tap water pending further notice.

"We're trying to remedy the situation and will keep you posted," read a notice written on scarlet paper.

However, Huang said, the contamination was "not serious."

"Tap water still appears clear with no odor", he added. "It's safe for washing and bathing."

But a resident surnamed Wang showed reporters apparent evidence to the contrary by producing two pails of water he stored on Monday. Dark sediment was clearly seen on the bottom of the buckets.

Wang and his neighbors have joined in a rush for spring water in mountains near their homes. "Many families have bought new pails", he said. "Some carry water on motorbikes, while others use shoulder poles."

Da'an town has several spring water resources nearby, so drinking water was not an immediate worry, said Huang Zhenyu, chief of the local government.

He said police and market regulators had been told to watch out for price hikes, however, as shopping runs on bottled water and food were considered likely.

The manganese-tainted water came from Da'an Waterworks, one of the two tap water suppliers in town. It provides water for more than 10,000 of the town's total 50,000 residents.

The cause of the contamination is still unknown. Town official Huang Zhenyu said there was no manganese processing plant or mine around.