What Residents Need to Know About Ashburn Water Quality

What Is the Source of Ashburn’s Drinking Water?

According to Loudoun Water, which provides drinking water to residents of Loudoun County, Ashburn’s water supply comes from two nearby sources: the Potomac River and Goose Creek. It also gets additional water from reservoirs in Virginia, Maryland, and West Virginia through deals with other water system providers.

Loudoun Water treats the water from Goose Creek itself, while the water that comes from the Potomac River may be treated by Loudoun Water or Fairfax Water.

How Is Ashburn Water Treated to Ensure Water Quality?

Ashburn’s water goes through a multi-step treatment process that includes:

• Chemical coagulation: Coagulants are added to the water so that unwanted particles stick together in clumps called “flocs.”
• Flocculation: The water is stirred and mixed so the particles form even larger clumps that are easier to filter out.
• Sedimentation: These large clumps are allowed to settle to the bottom of the water supply so they can be removed.
• Filtration: Additional contaminants are removed using a water filtration process that captures smaller particles left behind after sedimentation.
• Disinfection: Chlorine is added to the water to kill viruses and bacteria and to prevent bacteria from growing as it moves through the water system.

What Chemicals Are Used in the Water Treatment Process?

According to the 2022 Drinking Water Quality Annual Report, the following chemicals are added during the treatment process to maintain Ashburn’s water quality:

• Chloramine: Chloramine is a form of chlorine that’s used to disinfect the water by killing germs, viruses, and bacteria.
• Ozone: Ozone is used for additional protections against waterborne diseases and to improve the taste of the water.
• Orthophosphate: Orthophosphate is used to reduce the amount of lead that leaches into the water supply from pipes.

Although these chemicals help to ensure water safety and are regulated by the U.S. Environmental Protection Agency (EPA), they may leave behind some disinfection byproducts that may be a cause of concern for some consumers.

What Contaminants Are Found In Ashburn’s Drinking Water?

The Loudoun County 2022 Annual Drinking Water Quality Report [CR1] [MB2] reports that Ashburn’s water quality is in line with the guidelines set by the EPA and the Virginia Department of Health. However, nonprofit organizations like the Environmental Working Group (EWG) have more stringent recommendations than the EPA.

According to the EWG, Ashburn’s water supply contains 26 water contaminants, 12 of which exceed their health recommendations. These include:

Total Trihalomethanes (TTHMs)

Trihalomethanes are a group of chemicals that often end up in tap water as a result of the disinfection process. They include chloroform, bromoform, bromodichloromethane, and dibromochloromethane. Together, they’re called total trihalomethanes (TTHMs), and high levels of exposure are linked to an increased cancer risk.

Ashburn’s water has total TTHM levels of 30.2 parts per billion (ppm), lower than the EPA’s allowance of 80 ppb, but 202 times higher than the EWG’s guidelines:

• EPA maximum allowance: 80 ppb
• EWG recommended maximum: 0.15 ppb
• Ashburn maximum contaminant level: 30.2 ppb

Haloacetic Acids (HAA5)

Haloacetic acids (HAA5) are another byproduct of the disinfection process. They include monochloroacetic acid, dichloroacetic acid, trichloroacetic acid, monobromoacetic acid, and dibromoacetic acid. They are often measured together as HAA5, and are linked to an increased cancer risk with long-term exposure.

Ashburn’s water exceeds the EWG’s recommended maximum by 200 times:

• EPA maximum allowance: 60 ppb
• EWG recommended maximum: 0.1 ppb
• Ashburn maximum contaminant level: 20 ppb

An additional four acids make up the HAA9 grouping, for which there’s no legal limit. Ashburn’s water exceeds the EWG’s recommendation for HAA9 by 255 times.

Nitrates and Nitrites

Nitrates and nitrites enter the surface water and groundwater supply through runoff from agriculture, septic systems, and some urban sources. Nitrites in particular are linked to cancer, and contribute to cases of methemoglobinemia, or blue baby syndrome.

The EWG sets a maximum allowance of 0.14 parts per million for nitrates and nitrites, and Ashburn’s water exceeds this guidelines by 5.8 times:

• EPA maximum allowance: 10 ppm
• EWG recommended maximum: 0.14 ppm
• Ashburn maximum detected level: 0.805 ppm

Does Ashburn’s Drinking Water Contain Lead?

Lead is a major contaminant of concern for many renters and homeowners, especially those with children, due to its role in developmental and neurological disorders.

According to the 2022 Annual Drinking Water Quality Report, Ashburn’s source water is free from lead, and lead hasn’t been used in residential piping since 1986. It also adds orthophosphate to the water, a chemical that reduces lead leaching out of pipes.

Still, some older homes may have lead pipes that increase the risk of lead exposure. Residents can call the Safe Drinking Water Hotline (800-426-4791) to find out more about how to test your tap water for lead and minimize your exposure.

Does Ashburn’s Drinking Water Contain PFAS?

Heavy metals and disinfection byproducts aren’t the only contaminants of concern to watch out for. Environmental groups have raised the alarm about PFAS — per- and polyfluoroalkyl substances — also known as forever chemicals.

These substances are associated with industrial use, for example, firefighting foams used at airports or military bases.

The EWG found high levels of PFAS in 19 tap water samples from Northern Virginia, calling it a “hotspot” for forever chemicals in supposedly potable water.

The good news for residents of Ashburn is that PFAS levels were lower than in other parts of Northern Virginia — up to 7.8 parts per trillion compared to 62.4 ppt in Prince William County — although still higher than the recommended limit of 1 ppt.

This may be due to the fact that Ashburn’s drinking water comes from the Potomac River rather than the Occoquan Reservoir, which had higher PFAS levels.

Does Ashburn’s Tap Water Contain Fluoride?

Yes, Loudoun Water adds fluoride to the drinking water at low levels to benefit dental health. The Loudoun Water Trap Rock Water Treatment Facility has fluoride levels of 0.58 ppm, lower than the 4 ppm maximum allowed by the EPA.

How Is Ashburn’s Water System Tested?

The Ashburn water supply is tested regularly in order to comply with the Safe Drinking Water Act of 1974. The central system undergoes the following types of tests:

Bacteriological testing: Ashburn’s water is tested for E. coli and other bacteria at up to 180 locations each month. Loudoun Water also tests for Cryptosporidium to ensure that concentrations are below 0.075 oocysts per liter. Current levels are 0.0008 oocysts, which is not considered a concern for people in good health.

HAA5 and TTHMs: Loudoun Water tests for these disinfection byproducts on a quarterly basis at 12 different locations in the county’s water system.

Corrosion control: Ashburn’s water is also monitored for pH, which plays a role in reducing corrosion from lead and copper pipes.

Loudoun Water publishes water test results online and in its annual water quality report so residents can compare the test results against the EPA’s guidelines.

Which Water Filters Improve Ashburn Water Quality?

Ashburn’s water quality is tested and treated regularly, but some residents may choose to take matters into their own hands and install a home water filter for added protection. But which type of water filter is best for removing contaminants in Ashburn?

That depends on which contaminants you’re most concerned about. Activated carbon filters and reverse osmosis filters are both effective, but reverse osmosis filters are a better choice if you want to remove contaminants like PFAS and nitrates.

If you’re mostly concerned about chlorine and improving the taste of your water, then activated carbon filters may be more cost-effective and convenient.