Is DC Tap Water Safe to Drink? A 2026 Guide

If you live in Washington, DC, your tap water comes from the Potomac River, treated by the Washington Aqueduct and delivered by DC Water. It is tested constantly and meets every federal Safe Drinking Water Act limit. So the short answer is: yes, it is legal to drink.

But "legal" and "health-optimal" are not the same thing. Federal limits (MCLs) were largely set decades ago and are far weaker than the health-based guidelines used by the Environmental Working Group (EWG), which reflect the levels associated with roughly a one-in-a-million lifetime cancer risk.

What EWG flags in DC water

According to EWG's Tap Water Database, DC Water's supply contains several contaminants above those health guidelines, the most notable being disinfection byproducts created when chlorine reacts with organic matter in the Potomac:

• Bromodichloromethane, a disinfection byproduct linked to cancer and effects on fetal development.
• Dichloroacetic acid, a haloacetic acid associated with cancer and reproductive harm.
• Total trihalomethanes (TTHMs), a regulated group of disinfection byproducts.
• Hexavalent chromium (chromium-6), the "Erin Brockovich" chemical, an unregulated contaminant with no federal limit.

Why disinfection byproducts matter

Chlorination is essential. It stops waterborne disease. The tradeoff is that chlorine reacts with natural organic material to form byproducts. Utilities across the DC region that draw from the Potomac share this profile, which is why the numbers look similar in Arlington and Alexandria too.

How to reduce these contaminants at home

A point-of-use reverse osmosis (RO) system is the most effective way to reduce every one of these contaminant classes at the tap. RO forces water through a membrane with pores around 0.0001 microns, small enough to reject dissolved contaminants that carbon filters alone miss, including chromium-6 and PFAS.

You can see the exact contaminants detected in your zip code with our Washington, DC water report, then explore how the Sanavia Hydra RO system addresses them.