What's really in your Northern Virginia tap water?

Northern Virginia tap water is clean and safe to drink, but it has three traits that matter for your house. It's moderately hard to hard, it's disinfected with chloramines most of the year, and PFAS have been detected in one of its main sources. Those three facts explain why your dishwasher leaves spots, why your shower head clogs, and why the filter you bought may not be doing much.

Here's what each one means for your plumbing, and what works to treat it.

Where the water comes from

Most Northern Virginia homes get their water from Fairfax Water, which serves most of the region and draws from two main sources: the Potomac River and the Occoquan Reservoir. Both are surface water, and the overall quality is good. Fairfax Water tests for a long list of contaminants every year, and the results are public.

Treatment is designed for public health, though, not for how your water heater or faucets hold up. What's left in the water after treatment is what shows up as scale on your fixtures and an off taste in your coffee.

Is Northern Virginia water hard?

Yes. Fairfax Water delivers moderately hard to hard water, roughly 5 to 10 grains per gallon. That's squarely in the range where you start to notice it on fixtures and appliances.

Hard water won't hurt you. It shortens the life of water heaters and fixtures. The minerals build up inside tanks, valves, and shower heads, which cuts efficiency and wears equipment out early. We get regular calls about water heaters that failed ahead of schedule and fixtures clogged with mineral buildup, and we've written more on how hard water wears out appliances.

Hardness also shifts with the season and the source. When the system draws more heavily from the Potomac than the Occoquan, or the other way around, you may notice a change in how soap lathers and how fast deposits form.

Chloramines

Fairfax Water uses chloramines for disinfection most of the year and temporarily switches to free chlorine for a short stretch each spring. Chloramines last longer in the pipes than chlorine does, which means steadier protection against bacteria all the way to your tap.

The catch is filtering it out. Standard pitcher filters and basic carbon filters don't do a good job on chloramines. Chloramine reduction calls for catalytic carbon or a filter specifically rated for chloramines. If you're shopping for filtration, this is the detail that decides whether the equipment works on your water or just looks like it does.

PFAS

PFAS (per- and polyfluoroalkyl substances), often called "forever chemicals," have been detected in the Occoquan source, and Fairfax Water is working on treatment at the plant level.

You don't have to wait on that to deal with it at home. Reverse osmosis (RO) systems reduce PFAS at the tap, and placement and system design make a real difference in how well an RO unit performs and how convenient it is to live with. We cover the topic in more depth in our post on PFAS in Northern Virginia water.

Loudoun Water and wells are different

Not every home here gets Fairfax Water. Loudoun Water's supply and blend differ from Fairfax Water's, so the chemistry can differ too. Ashburn and Sterling are mostly on Loudoun Water, while parts of western Loudoun rely on private wells.

Well water can range from very soft to very hard depending on local geology. It can also bring iron, sulfur, and bacteria into the picture, and each of those needs its own treatment approach. That's a big part of why we test before we recommend anything.

What we recommend

For most homes on municipal water, the setup that works best is whole-house carbon filtration paired with an under-sink reverse osmosis system. The carbon system handles chloramines and improves taste at every tap in the house. The RO unit gives you high-purity drinking water and reduces specific contaminants like PFAS.

A water softener is a different tool. It handles hardness, which protects fixtures and your water heater, but it doesn't remove chloramines or PFAS. If your water still tastes like a swimming pool after a softener goes in, that's why.

The right combination depends on your actual water chemistry, not on a general recommendation. On municipal water, a few streets apart is usually the same water. Switch utilities, or move to a well, and it can be a different story.

Start with a test

We test water chemistry as part of our plumbing diagnostics, because it affects everything from pipe corrosion to how long your appliances last. Our technicians check the basics that drive filtration choices, like hardness and disinfectant, and lab analysis covers contaminants like PFAS when you want that level of detail.

Pioneer Plumbers is a family-owned, licensed and insured company, and once we know what's in your water, you get a written, upfront quote before any work begins. Call (703) 508-3088 to set up a water test, and we'll walk you through what we find and what we'd install.