Chlorine in water to be doubled

Wednesday, Oct. 17, 2001 | 9:15 a.m.

Las Vegas Valley Water District customers may soon notice a stronger chlorine smell in their tapwater.

The water district is gradually doubling the amount of the disinfectant chemical to kill any bacteria that a would-be attacker would introduce to the water system, district General Manager Pat Mulroy told Clark County commissioners on Tuesday.

The additional chlorine will raise the level from .5 parts-per-million to 1 part-per-million -- or one chlorine molecule for every million water molecules.

"Our customers will therefore experience a slightly greater chlorine taste in their water, but it's for their safety," Mulroy told the commissioners, who also serve as the water district's board of directors.

Vince Alberta, water district spokesman, said the federal limit for chlorine in public water systems is 4 parts-per-million.

The chlorine also will serve to warn the system's operators if any contaminant suddenly enters the water system, which serves about 1.4 million people.

Deputy General Manager Richard Wimmer said the system constantly monitors the level of chlorine in the water. A sudden drop in the chlorine level would indicate the chemical is reacting to something introduced to the system, he said.

The chlorine addition is just one of several steps the district is taking to protect the water supply.

The district's 42 buried reservoirs are kept full to keep water ready for delivery to users, Wimmer said. Each holds about 10 million to 40 million gallons.

The largest reservoir for the system is Lake Mead, which holds about 26 million acre-feet of water, or about 8.5 trillion gallons. Mulroy said the lake itself is an unlikely target for terrorists because any chemical or biological material would be massively diluted by the volume of water.

"It would be extremely difficult to contaminate," she said.

Other steps to protect the water supply include new locks, electronic monitoring and daily regular and spot inspections of water system facilities throughout the valley.