Where does Loudoun Water, the largest drinking water supplier in Loudoun County, obtain its water, how it is treated before being distributed to customers, and how we can be confident we are getting the best product possible?

First, a confession. I do not live in Middleburg. Instead, I live in an area of Loudoun County whose water is supplied by Loudoun Water. In fact, Loudoun Water provides drinking water to more than 186,000 customers primarily east of Route 15 from South Riding to Sterling. You probably know that Middleburg uses groundwater, and is one of only four incorporated towns in the county not supplied by Loudoun Water, the others being Leesburg, Purcellville, and Lovettsville.

So where does Loudoun Water get its water? Two sources, actually, intakes in the Potomac River and Goose Creek, or, more accurately, Goose Creek Reservoir. However, Loudoun Water's primary function is water distribution. In reality, its drinking water comes from Fairfax County. Loudoun Water purchases fully treated water through fairly complicated contractual agreements from Fairfax Water (about 95 percent), and from the City of Fairfax. These agreements call for Loudoun Water to receive up to 53 million gallons per day of treated, drinkable water.

So how does Fairfax Water treat the water it furnishes Loudoun Water and why is it treated? Let's answer these questions in reverse order.

Remember that water is the universal solvent. As it moves overland or resides underground it continually is dissolving minerals and other natural material as well as less desirable material resulting from human and animal activity. Naturally occurring inorganic substances can be things like salts and metals, but these substances can also occur as a result of human activity – think salt from streets in winter. Other goodies water may pick up include microorganisms – you've heard of Cryptosporidium, a nasty that can cause abdominal infections (we may call it something else.) Other substances that may find their way into water include radioactive contaminants, and pesticides or other organic chemicals. Finally, sediment picked up by water can be the cause of turbidity (cloudiness.)

Yuck! We're drinking this stuff? But wait! We're not, we're really not. Fairfax Water uses a five step treatment process that involves chemical coagulation, flocculation, sedimentation, filtration, and disinfection. So what do these big words actually mean? The first three simply are processes that make contaminants group together and settle out to clarify the water before it is filtered. Finally, after filtration, the water is disinfected with chlorine and ozone to kill the microorganisms that might have made it through the filtration process. The finished water is tested daily for microorganisms. Yay!

These techniques have been developed over many years and are in use in one form or another by every water system in the U.S. that uses supplies derived from surface water sources. As a career "water guy," I feel confident that every time I draw a glass of water from my kitchen sink, it is as safe as water from any other source including bottled water. Yes, Loudoun Water and Fairfax Water really do it right.