The Loudoun County Sanitation Authority plans to build two or three water storage tanks south of Route 50 in the next two years, said spokeswoman Samantha Villegas.

The steel lollipop-shaped tanks will hold 6 million gallons of water -- either 2 million or 3 million gallons apiece -- and will supply water to more than 7,000 homes and businesses in the Dulles South area, Villegas said. They will be similar to the two tanks at Ryan Road and Route 659 in Brambleton, which sit on an elevated five-acre site. Each tank is about 180 feet tall.

The tanks will not change where the county's water comes from or how it gets to customers. Their purpose is to regulate water flow and pressure.

"Water tanks aren't holding onto water that is closed off from the system, waiting to be tapped. Rather, they are fully open and connected to the water in the system," Villegas said. "More than anything, they're helping regulate flow, pressure and water levels in the pipes."

The authority says water tanks maintain consistent water flow and pressure through a radio-frequency system. Their ability to regulate water flow and pressure is crucial during periods of high water use -- such as warm days when many residents water their lawns or when firefighters tap hydrants during a fire. Water tanks also maintain flow and pressure in the case of water failure, a water-main break or during a storm, Villegas said. Without water tanks, customers might notice low water pressure or volume in a shower head or a hose.

The Loudoun authority buys water from the Fairfax County Water Authority and the City of Fairfax. The plants that provide water to Dulles South customers are the Corbalis water treatment plant in Herndon and the Lorton water treatment plants, owned by the Fairfax County Water Authority, and the Goose Creek water treatment plant in Ashburn, run by the City of Fairfax.

The authority is accepting suggestions for tank sites. A good site would be easily accessible to allow for filling and draining and would not have historical significance or be the habitat of any endangered species, Villegas said. It would also have room for landscaping and be visually appealing, Villegas said. LCSA will place large balloons at potential tank sites in November.

LCSA hopes to pick a site by 2006 and complete building in 2007, Villegas said. Each tank is expected to cost $3 million to $5 million.

To suggest a site or to apply to be a member of the water tank citizens advisory committee, call 866-771-1096 or visit www.lcsa.org.

Committee applications will be accepted until Sept. 16, and members will be chosen by early October.

The Loudoun County Sanitation Authority has proposed building two or three water storage tanks south of Route 50 that would be similar to this tank at Ryan Road and Route 659 in Brambleton.