Water Filters Washington
Potomac River Water Leaves the Plant Clean. Your DC Service Line Is Another Story.
The U.S. Army Corps of Engineers' Washington Aqueduct treats Potomac River water at the Dalecarlia and McMillan plants, and DC Water carries it through 1,300 miles of mains. By the time it reaches your tap it can pick up lead from one of the estimated 31,016 lead service lines still in the ground, chloramine disinfection byproducts and nitrate from upstream farmland, at an average hardness of 7 GPG. AFW Filters matches every DC home and apartment to the right water purification RO system, water conditioner for hard water or water softener system.
Contaminant Snapshot
visitors on DC Water
5 to 10 GPG range
EWG health guidelines
money-back guarantee
What's in Washington, DC Tap Water?
| Contaminant | Severity | DC Level | Source | Best Treatment |
|---|---|---|---|---|
| Lead (service lines) | CRITICAL in older homes | 90th percentile 2 ppb; 1 of 105 homes above the 15 ppb action level, highest 35.9 ppb (2024) | Lead and galvanized service lines, pre-1987 solder | RO at the kitchen tap |
| Disinfection byproducts (TTHMs, HAA5) | HIGH | TTHMs 22 to 68 ppb and HAA5 13 to 55 ppb in single samples; 9 of the 13 contaminants above EWG guidelines are byproducts | Chlorine and chloramine reacting with Potomac organic matter | Catalytic carbon or RO |
| Nitrate | MODERATE | Up to 2 ppm (MCL 10); 14 times EWG's guideline | Upstream fertilizer runoff and wastewater | RO |
| Chromium-6 | MODERATE | 4 times EWG's health guideline | Natural deposits, industry | RO |
| PFAS | MODERATE | PFOS up to 3.1 ppt and PFOA up to 2.4 ppt in 2025, under EPA's 4 ppt limits | Upstream industrial and consumer sources | RO or whole-house PFAS system |
| Hardness | MODERATE | 7 GPG average, 5 to 10 GPG range | Potomac River minerals | Water conditioner for hard water or softener |
How Hard Is the Water Across the DC Area?
Every DC ward drinks the same Potomac water from the Washington Aqueduct, so hardness inside the District stays in a narrow 5 to 10 GPG band that shifts with river conditions. Cross into the suburbs and it changes: WSSC Water's Potomac plant runs harder, its Patuxent plant runs softer, and Northern Virginia sits in between.
| Area | Communities | Utility & Source | Hardness |
|---|---|---|---|
| District of Columbia (all 8 wards) | Capitol Hill, Georgetown, Columbia Heights, Brookland, Anacostia | DC Water, treated by the Washington Aqueduct (Potomac) | 5 to 10 GPG, 7 average |
| Montgomery County & lower Prince George's | Bethesda, Silver Spring, Rockville, lower PG | WSSC Water, Potomac plant | 4.6 to 12.5 GPG, 9.0 average |
| Laurel area | Laurel and northern Prince George's | WSSC Water, Patuxent plant (Triadelphia and Rocky Gorge reservoirs) | 3.4 to 5.0 GPG, 4.1 average |
| Alexandria | City of Alexandria | Virginia American Water, supplied by Fairfax Water (Potomac and Occoquan) | About 6.6 GPG |
Legend: 0 to 3.5 GPG soft · 3.5 to 7 moderate · 7 to 10.5 hard · 10.5+ very hard. Sources: DC Water 2025 Drinking Water Quality Report (2024 data); WSSC Water 2025 Tap Water Analysis; Virginia American Water, Alexandria typical water quality. WSSC figures converted from mg/L at 17.1 mg/L per grain.
Six Reasons Washington, DC Tap Water Needs Treatment
31,016 Lead Service Lines Still in the Ground
Disinfection Byproducts from Potomac Organic Matter
Chloramine Most of the Year, Chlorine Every Spring
Nitrate from Upstream Farmland
Low-Level PFAS
7 GPG Hardness, Right at the Hard-Water Line
DC Water Quality by Ward and Recommended Setup
Hardness is the same across the District, so the real difference ward to ward is how many lead service lines remain. Counts are DC Water's estimates as of 30 Sept 2025.
| Ward & Neighborhoods | Source | Hardness | Lead Lines Left | Key Contaminants | Severity | Recommended Bundle |
|---|---|---|---|---|---|---|
| Ward 5: Brookland, Eckington, Trinidad | Potomac via Aqueduct | 5 to 10 GPG | 5,697 (most of any ward) | Lead, DBPs, nitrate | CRITICAL | Gold Seal RO + catalytic carbon |
| Wards 4 and 7: Petworth, Brightwood, Deanwood, Benning | Potomac via Aqueduct | 5 to 10 GPG | 9,028 combined | Lead, DBPs | CRITICAL | Gold Seal RO + salt-free conditioner |
| Ward 6: Capitol Hill, Navy Yard, H Street | Potomac via Aqueduct | 5 to 10 GPG | 3,938 | Lead in row houses, DBPs | HIGH | RO system + catalytic carbon |
| Ward 1: Columbia Heights, Adams Morgan, Shaw | Potomac via Aqueduct | 5 to 10 GPG | 3,810 | Lead, DBPs | HIGH | RO system |
| Ward 3: Cleveland Park, Tenleytown, Chevy Chase DC | Potomac via Aqueduct | 5 to 10 GPG | 3,796 | Lead, DBPs, scale | HIGH | RO system + 32k softener |
| Ward 2: Georgetown, Dupont Circle, Foggy Bottom | Potomac via Aqueduct | 5 to 10 GPG | 2,799 | Lead in historic buildings, DBPs | HIGH | RO system |
| Ward 8: Anacostia, Congress Heights | Potomac via Aqueduct | 5 to 10 GPG | 1,948 | Lead, DBPs | MODERATE TO HIGH | RO system |
| Montgomery County (WSSC Potomac) | Potomac | 4.6 to 12.5 GPG | n/a | Harder water, DBPs | MODERATE | 32k to 40k softener + RO system |
Water Purification RO Systems for Washington, DC Homes and Apartments
DC's water problem is mostly about what happens between the main and your glass. An under-sink RO system reduces lead, byproducts, nitrate, chromium-6 and PFAS at the tap, whether you own a row house or rent an apartment.
View All RO Systems →5-Stage PT-505 Vertex Gold Seal Certified Reverse Osmosis System 50 GPD
Best for homes with a lead or galvanized service line. Third-party certified for homes on DC Water's lead inventory, and for the six months of filtering DC Water recommends after a line is replaced.
5-Stage Zoi Alpha Pure Reverse Osmosis System
Best for apartments and condos. Compact under-sink system for chloramine byproducts, nitrate and trace metals. Connects to the cold-water line with a dedicated faucet.
Mikro Alpha 4-Stage Portable Reverse Osmosis System with 75 GPD Membrane
Best for renters who can't drill the counter. Portable RO that needs no permanent plumbing changes, so it moves with you when the lease ends.
Water Conditioners for Hard Water vs. a Water Softener System in DC
At 7 GPG, DC sits right where scale starts to show. A salt-free conditioner stops buildup without salt or a drain line, while a compact softener gives the full soft-water feel.
View All Salt-Free Conditioners →Scale Sentry RESIDENTIAL Salt-Free Home Water Conditioner with HIGH-FLOW Radial Flow Carbon Prefilter
Best salt-free option for DC row houses. Prevents scale from DC's 5 to 10 GPG water and adds a carbon stage for chlorine taste during the spring switch.
Upgraded 1 Cubic Foot (32k) On Demand Whole Home Water Softener with 10% Crosslink Resin, Pentair Tank
Best compact water softener system. A family of four on 7 GPG uses about 2,100 grains a day, so 32,000 grains runs two weeks between regenerations. Fits basement and utility closets.
ScaleMaster HardWater Wizard RW10 Electronic Water Conditioner — 1-Inch Pipe
Best for tankless water heaters on a budget. Electronic conditioner rated for water up to 40 grains, with no salt and no maintenance.
40k Water Softener with 10% Resin and Fleck 5600SXT Controller, Pentair Tank
Best for Montgomery County homes on WSSC water. WSSC's Potomac plant averages 9 GPG and reaches 12.5. A family of four there uses about 2,700 grains a day, so 40,000 grains runs roughly two weeks between regenerations.
Salt-Free Conditioner vs. Salt-Based Softener at DC Hardness
Salt-Free Water Conditioner for Hard Water
- Stops scale from sticking; minerals stay in the water
- Fits DC's 5 to 10 GPG well
- No salt, no drain, ideal for condos and row houses
- Little to no maintenance
Salt-Based Water Softener System
- Removes calcium and magnesium completely
- Worth it in harder Montgomery County water (up to 12.5 GPG)
- Soft feel on skin and hair, less soap
- Needs salt and a drain connection
Whole-House Filters for DC Chloramine, Lead and PFAS
For protection at every shower and faucet, not just the kitchen, treat water where it enters the house. If your home is on DC Water's lead inventory, a whole-house lead stage covers the shower and bath taps too, while RO handles drinking water.
View All Catalytic Carbon Systems →GreenFlo Catalytic Carbon 15 Upflow System
Best for chloramine and byproducts. Upflow design with no backwashing or wastewater, which suits homes without a convenient drain.
Whole House PFAS Water Treatment System 8 GPM Flow Rate
Best for whole-home PFAS reduction. ResinTech PFAS-selective resin in a compact 12" x 48" tank for homeowners who want PFAS reduced at every tap.
20-Inch 2 Stage Whole House Filter with Lead-Cyst-Heavy Metal Reduction
Best whole-house option while you wait for a lead line replacement. A sediment stage followed by a Matrikx Pb1 lead filter, in 20-inch housings with 1-inch ports. It catches the particles that can shake loose during and after a Lead Free DC replacement. Keep a certified RO at the kitchen tap for drinking water.
20-Inch 2 Stage Whole House Water Filter — Sediment & Catalytic Carbon Filtration
Budget chloramine filter for row houses. Sediment and catalytic carbon cartridges in two compact housings, for chloramine most of the year and straight chlorine during the spring switch. Fits a basement or utility closet where a tank won't.
Why DC Homeowners and Renters Choose AFW Filters
We Read Your Service Line Before We Sell You Anything
We'll walk through DC Water's service line map with you and point you to the free Lead Free DC programs, then size what you still need.
We Don't Oversell Softeners
DC water averages 7 GPG, so many homes need a conditioner or a compact 32,000 grain unit, not a big system.
Real Water Experts by Phone
Call 785-661-2241, weekdays 8am to 4pm CT, for help reading DC Water's report.
120-Day Money-Back Guarantee
If the system isn't right for your water, we make it right.
Reviews from AFW Filters Customers
“Service was great, documentation was good, and shipping was fast and well protected.”
“Water output is great. Never thought I could install the whole setup myself, but the manual and videos are very clear.”
“Great price, easy experience, and quick shipping. Love the Fleck 5600 SXT setup we purchased.”
Frequently Asked Questions
Is DC tap water safe to drink?
How do I know if my DC home has a lead service line?
Will a water purification RO system remove lead from my tap?
Do I need a water softener system in Washington, DC?
Why does DC water smell like chlorine in the spring?
Is there PFAS in DC water?
Do water conditioners for hard water work on DC's water?
Can I install an RO system in a DC rental?
DC's Water Risk Lives in the Pipes. Get the Setup That Fits Your Building.
A Brookland row house on a lead line, a Georgetown condo with old brass fixtures and a Bethesda home on harder WSSC water need different setups. AFW Filters has matched homes to the right systems since 1998.