Fairfax Water Qauality

 

Every year public water suppliers are required to issue an annual drinking water quality report to their customers before July first of the following year. In June Fairfax Water released their report which can be found in its entirety at this link.  Fairfax Water owns and operates the James J. Corbalis Jr. and the Frederick P. Griffith Jr. treatment plants. These plants are the primary source of water for most of Fairfax County and portions of Loudoun County and Prince William County. Fairfax Water acquired the City of Falls Church water distribution system as well as an area that serves approximately 120,000 people and obtain their water from the Dalecarlia and McMillan treatment plants, part of the Washington Aqueduct which is owned and operated by the U.S. Army Corps of Engineers.

The result is that now Fairfax Water provides water to county residents from their two water treatment plants and buys water from the Washington Aqueduct to supply residents in and around the City of Falls Church. These were historic systems that were once town owned. The newer developments around Merrifield and the Dunn Loring Metro Station are supplied water from the Fairfax Water owned plants. Thus, they are required to report on the water quality of all these sources. 

Both the Washington Aqueduct and Fairfax Water run excellent water treatment plants. All four plants use advanced technologies and practices in drinking-water treatment, which is the process of cleaning raw water to make it safe to drink. Fairfax Water reports that their water consistently surpasses all federal (US EPA Safe Drinking Water Act) and state standards. Of the 182 compounds that are required to be tested for, very few were found in the finished drinking water. Those found were in concentrations well below the EPA’s maximum contaminant levels under the Safe Drinking Water Act. Fairfax Water’s state-certified Water Quality Laboratory performs or manages the testing required by federal and state regulations. The Washington Aqueduct does the testing for the water they supply. 

Two issues emerged from the review of the water quality report. The first is the rising salt level in the Occoquan Reservoir and from the Potomac River. From comparing the Washington Aqueduct numbers to the Fairfax Water numbers it is clear that the Occoquan Reservoir has a higher level of salinity than the Potomac River, but both levels are rising. Sodium is a secondary contaminant in drinking water it is recommended that the level be controlled below 20 mg/L by the EPA.

The ICPRB, the Virginia Department of Environmental Quality (VDEQ) and the Northern Virginia Regional Commission have developed a voluntary Salt Management Strategy published in 2020 to try and reduce the largest source of salt/ chloride to the Potomac, its tributaries and the Occoquan Watershed, but this alone may not slow the increasing salinization of our source water for drinking as road construction continues at an alarming pace. As we try to encourage the adoption of the voluntary salt management strategy, we keep building roads and paving over the counties.

Sodium and chloride the elements that make up salt and break apart in water are washed off road by rain and melting snow and flow into local waterways or seep through soils into groundwater systems with negative impacts on water quality and the environment. Salts pollute drinking water sources and are very costly to remove. The only available technology to remove salt from the source water is reverse osmosis which could cost Fairfax Water alone $1-2 billion to install and requires a significant amount of energy to run. 

The second problem that was seen in the water quality report was the presence of PFAS above the target regulatory level. In April 2024, the EPA announced the final national primary drinking water standards for six poly- and perfluoroalkyl substances (PFAS). Public water systems have five years (by 2029) to implement solutions that reduce these PFAS if monitoring shows that drinking water levels exceed the maximum contaminant levels (MCLs). Fairfax Water has stated that they will ensure their water meets these standards by the regulatory date.

Even with these issues, the quality of the finished drinking water being produced at Washington Aqueduct and Fairfax Water meets or exceeds all United States Environmental Protection Agency (US EPA) current standards and requirements. The water quality report released in June covers the sampling done during calendar year 2023. There were no violations of the U.S. EPA’s Safe Drinking Water Act.