What's in Fairfax County Tap Water? 14 Contaminants Above Health Guidelines

If you live in Fairfax County, your tap water meets federal standards. That sounds reassuring, and it should count for something. It also doesn't tell you the whole story. The Environmental Working Group's Tap Water Database lists 14 contaminants in Fairfax County Water Authority water that exceed EWG's health guidelines. They include PFAS, chlorine byproducts, nitrate, and hexavalent chromium. Here's what the data shows and what you can do about it.

Fairfax County Water Authority at a glance

The Fairfax County Water Authority serves 1,121,613 people in Virginia and draws from surface water. EWG's report covers testing data from 2013 to 2024. Across that period, 32 contaminants were detected in the water. Fourteen of them came in above EWG's health guidelines. For the most recent quarter assessed by the EPA, April through June 2024, the utility was in compliance with federal health-based standards. So the utility isn't breaking any rules, and that distinction matters for everything that follows.

Legal does not equal safe

Federal limits and health guidelines measure two different things. A legal limit is an enforceable standard, and EWG points out that many of them haven't been updated in almost 20 years. A health guideline is a benchmark set at a level where scientists see little or no risk over a lifetime. Take haloacetic acids, known as HAA5. The utility's level was 16.4 ppb, well under the 60 ppb legal limit, but that is 164 times EWG's guideline of 0.1 ppb. Guidelines like this one are conservative on purpose, and they aren't diagnoses. They do show you how much room exists between what's legal and what researchers consider ideal.

Chlorine byproducts are the biggest numbers

Water utilities add chlorine and other disinfectants to kill germs, and that protection matters. The tradeoff is that disinfectants react with organic matter in the water and form byproducts. Fairfax County's water contained chloroform at 17.7 ppb, which is 44 times EWG's 0.4 ppb guideline. Bromodichloromethane came in at 6.59 ppb, or 110 times its guideline, and the group of nine haloacetic acids called HAA9 measured 26.6 ppb, 444 times its guideline. Total trihalomethanes, or TTHMs, measured 27.8 ppb against an 80 ppb legal limit. EWG says these byproducts increase cancer risk and may cause problems during pregnancy.

PFAS in Fairfax County water

EWG's report shows eight PFAS detected in Fairfax County Water Authority water. The 6:2 fluorotelomer sulfonic acid measured 3.17 ppt, which is 3.2 times EWG's 1 ppt guideline, and it has no legal limit at all. PFOA measured 0.417 ppt, 4.6 times EWG's guideline of 0.09 ppt. PFOS was detected at 0.392 ppt, and EWG lists a proposed legal limit of 4 ppt for both PFOA and PFOS. Several others showed up too, including PFHxA at 2.71 ppt and PFPeA at 2.88 ppt. Federal PFAS rules have been changing, so check the current limits before you rely on any single number.

Nitrate and hexavalent chromium

Nitrate is a fertilizer chemical that reaches drinking water through agricultural and urban runoff, wastewater plant discharges, and septic tanks. Fairfax County's level was 1.12 ppm, far under the 10 ppm legal limit but 8 times EWG's 0.14 ppm guideline. EWG says excess nitrate can cause oxygen deprivation in infants and increase cancer risk. Hexavalent chromium, a carcinogen, measured 0.103 ppb, which is 5.2 times EWG's 0.02 ppb guideline. It can come from industrial pollution or from natural mineral deposits. Neither one has a legal limit that matches EWG's health benchmark, so both pass inspection easily.

Fairfax is not an outlier

Here's the honest part. Many of these numbers sit close to national averages, and some sit below them. PFOA in Fairfax County was 0.417 ppt compared with a national average of 0.796 ppt. Hexavalent chromium was 0.103 ppb against a national average of 0.44 ppb, and TTHMs were 27.8 ppb against 29.1 ppb. That doesn't make the water bad. It means this is what typical American tap water looks like when you hold it against health guidelines instead of legal limits. The gap between the two is the real story.

Which filters work for Fairfax County tap water

EWG's filter guide rates reverse osmosis as the most effective option for this utility. It lists reverse osmosis as filtering all 14 contaminants that exceed guidelines, plus 15 others. Carbon filters handle 11 of the 14 and 8 others, with a lower upfront cost and less maintenance. EWG also notes that reverse osmosis costs more upfront, needs more maintenance, and uses more water. Those are real tradeoffs, and you should weigh them against what you want out of your water. For a household that wants the broadest coverage, including nitrate and hexavalent chromium, reverse osmosis covers the most ground.

What to do next

Start with your utility's annual water quality report and compare the numbers to health guidelines, not just legal limits. Then test the water at your own tap with an accredited lab, since your home plumbing can add contaminants like lead that the utility's testing never sees. Ask the lab which compounds the panel covers, because many PFAS tests only look for a short list of known compounds. If you decide to filter, look for NSF certification and published performance data for the specific contaminants you care about. Test again after installation, so you know the system is doing its job. If you're pregnant or have an infant at home, talk with your doctor about what's right for your family.

At Sanavia Water, we build reverse osmosis systems for homeowners who want real protection from what's in their water. We believe you should see the data and then decide for yourself. Our team can help you read your local water report and choose a system that fits your home. If you live in Northern Virginia and want to know where to start, reach out and we'll walk you through it.

Frequently asked questions about Fairfax County tap water Is Fairfax County tap water safe to drink?

EWG reports that Fairfax County Water Authority water was in compliance with federal health-based standards for the latest quarter it assessed. That's the legal bar, and the utility met it. EWG's health guidelines are stricter, and 14 contaminants exceeded them. Those guidelines are benchmarks for long-term risk, not a statement that the water will make you sick. If you have specific concerns, especially during pregnancy or for infants, talk with your doctor.

Does Fairfax County tap water contain PFAS?

Yes, EWG's data shows eight PFAS detected in the water. Two of them, 6:2 FTSA and PFOA, came in above EWG's health guidelines. The 6:2 FTSA has no legal limit, and the PFOA level sat under the 4 ppt limit that EWG lists as proposed. PFAS rules have been shifting, so check current federal standards for the latest numbers. A lab test at your own tap gives you the clearest picture.

What are trihalomethanes and haloacetic acids?

They're disinfection byproducts that form when chlorine reacts with organic matter in water. Trihalomethanes include chloroform, bromodichloromethane, dibromochloromethane, and bromoform. Haloacetic acids are a related group, and five of them are regulated together as HAA5. EWG says these byproducts increase cancer risk and may cause problems during pregnancy. Reverse osmosis and activated carbon are the filter types EWG lists for reducing them.

What is the difference between a legal limit and a health guideline?

A legal limit is an enforceable federal standard that utilities must meet. A health guideline is a benchmark set at a level scientists consider to pose little or no risk over a lifetime. EWG says many legal limits haven't been updated in almost 20 years. That's why a utility can comply with every rule and still show contaminants above health guidelines. Reading both numbers side by side gives you a fuller picture of your water.

The bottom line

Fairfax County tap water meets federal standards, and it also contains 14 contaminants above EWG's health guidelines. The biggest numbers come from chlorine byproducts, with PFAS, nitrate, and hexavalent chromium on the list too. Many of these levels are close to national averages, which shows how wide the gap is between legal and ideal for most American water. Test your own tap, read the data yourself, and filter with a system that has real performance data behind it. When you're ready to take the next step, contact Sanavia Water and we'll help you find the right system for your home.

Source: https://www.ewg.org/tapwater/system.php?pws=VA6059501