Tap water and drinking water quality in Rockville, MD

WATER QUALITY REPORT

Rockville, MD tap water: what’s in it in 2026

Reviewed by Joe Letorney, 30-year water treatment expert · Former WQA Certified Water Treatment Specialist (CWS), Level VI

See best water filters for lead removal and what filters remove PFAS.

Serving 67K residents via Washington Suburban Sanitary Commission (WSSC Water) · Rockville, MD drinking water is supplied by Washington Suburban Sanitary Commission (WSSC Water). EPA and public water system monitoring commonly focus on issues such as Disinfection byproducts, PFAS monitoring, Lead in older home plumbing. Rockville shares the same Potomac/Patuxent WSSC system as Gaithersburg, Bethesda, and Silver Spring — plant-finished water is strong, but older premise plumbing can still add lead at the tap. Enter your ZIP for SDWIS violations, UCMR5 PFAS results, and NSF filter picks.

Check water hardness in Rockville →

WATER PROFILE — WSSC Water CCR 2024

Hardness

105 mg/L

Moderately Hard

TDS

210 mg/L

Low

7.5

Neutral

Disinfectant

Chloramine

⚠ Standard filters don't remove

Fluoride

0.7 mg/L

Added

Nitrate

1.1 mg/L

Below limit

Disinfection byproductsPFAS monitoringLead in older home plumbing

74/ 88

WATERCHECKUP SAFETY SCORE

Grade: B

Fair

WaterCheckup Safety Score — an independent index from EPA public data and our formula. Not your utility’s official water quality rating, an EPA compliance grade, or a test of water at your tap. How we score →

Same score for your ZIP — look up your ZIP for the full contaminant report

✅

GENERALLY OK

Based on water safety score

WHAT YOU SHOULD KNOW ABOUT ROCKVILLE WATER

Rockville water currently shows no major violations in EPA monitoring data. That said, your home's internal plumbing can add lead or other contaminants after water leaves the treatment plant — especially in homes built before 1986.

⚠Disinfection byproducts

⚠PFAS monitoring

⚠Lead in older home plumbing

Public water systems in Maryland

8,042

EPA PWSID (this report)

MD0150005

TTHMs (utility avg.)

54 ppb

HAA5 (utility avg.)

38.1 ppb

PFAS compounds (UCMR5)

Browse Maryland utilities →

LEGAL DOES NOT ALWAYS MEAN SAFE

Rockvillewater may meet federal EPA limits while still showing contaminants above independent health guidelines (EWG, state advisories). EPA MCLs are often set on treatment feasibility — not a "zero risk" threshold. Compare levels below to health guidelines and state/U.S. utility averages, then see which filter technologies address your profile.

CONTAMINANTS IN ROCKVILLE WATER

EPA UCMR5 PFAS plus utility/EWG averages from our contaminant bundle. Run a ZIP report for live SDWIS samples at your address.

Total Trihalomethanes (TTHMs)

54 ppb (EPA limit 80 ppb)360× health guidelineModerate

This utility

54.0

U.S. avg

31.0

State avg

51.4

EWG health guideline: 0.15 ppb

EWG Tap Water Atlas utility average (2021–2023) · U.S. utility avg (EWG Atlas sample): 30.97 ppb · MD utility avg: 51.43 ppb

Removes with: RO · Carbon

Haloacetic Acids (HAA5)

38.1 ppb (EPA limit 60 ppb)635× health guidelineModerate

This utility

38.1

U.S. avg

21.6

State avg

32.4

EWG health guideline: 0.06 ppb (HAA5)

EWG Tap Water Atlas utility average (2021–2023) · U.S. utility avg (EWG Atlas sample): 21.57 ppb · MD utility avg: 32.43 ppb

Removes with: RO · Carbon

Water Hardness

105 mg/L (EPA limit 150 mg/L)Lower concern

From WSSC Water CCR 2024

Removes with: RO · Ion exchange

Haloacetic Acids (HAA9)

50.5 ppbLower concern

This utility

50.5

U.S. avg

23.6

State avg

34.8

EWG Tap Water Atlas utility average (2021–2023) · U.S. utility avg (EWG Atlas sample): 23.64 ppb · MD utility avg: 34.80 ppb

Removes with: RO · Carbon

Barium

29.6 ppbLower concern

This utility

29.6

U.S. avg

43.5

State avg

35.9

EWG health guideline: 700 ppb

EWG Tap Water Atlas utility average (2021–2023) · U.S. utility avg (EWG Atlas sample): 43.45 ppb · MD utility avg: 35.90 ppb

Removes with: RO · Carbon · Ion exchange

Manganese

13.6 ppbLower concern

This utility

13.6

U.S. avg

5.69

State avg

6.29

EWG health guideline: 100 ppb

Long-term exposure at high levels may affect the nervous system. Staining and taste issues at lower levels.

Removes with: RO · Carbon

Chloroform

13.5 ppbLower concern

This utility

13.5

U.S. avg

17.8

State avg

19.8

EWG Tap Water Atlas utility average (2021–2023) · U.S. utility avg (EWG Atlas sample): 17.82 ppb · MD utility avg: 19.80 ppb

Removes with: RO · Carbon

Chlorate

11.2 ppbLower concern

This utility

11.2

U.S. avg

161

State avg

68.3

Can impair thyroid function — most concerning during pregnancy and childhood.

Removes with: RO · Carbon

PFPeA

6.7 pptLower concern

PFAS (“forever chemicals”) persist in the body. NSF 58 reverse osmosis or NSF P473-certified filters remove PFAS at the tap — standard pitchers do not.

Removes with: RO · Carbon

Bromodichloromethane

6.14 ppb102.3× health guidelineLower concern

This utility

6.14

U.S. avg

6.47

State avg

6.68

EWG health guideline: 0.06 ppb

THM component linked to cancer and reproductive harm with long-term exposure.

Removes with: RO · Carbon

Bromochloroacetic acid

4.83 ppb241.5× health guidelineLower concern

This utility

4.83

U.S. avg

3.86

EWG health guideline: 0.02 ppb

EWG Tap Water Atlas utility average (2021–2023) · U.S. utility avg (EWG Atlas sample): 3.86 ppb

Removes with: RO · Carbon

PFHxA

4.8 pptLower concern

PFAS (“forever chemicals”) persist in the body. NSF 58 reverse osmosis or NSF P473-certified filters remove PFAS at the tap — standard pitchers do not.

Removes with: RO · Carbon

Perfluoropentanoic Acid (PFPeA)

2.51 pptLower concern

This utility

2.51

U.S. avg

3.00

State avg

1.88

EWG Tap Water Atlas utility average (2021–2023) · U.S. utility avg (EWG Atlas sample): 3.00 ppt · MD utility avg: 1.88 ppt

Removes with: RO

Perfluorohexanoic Acid (PFHxA)

2.11 pptLower concern

This utility

2.11

U.S. avg

2.85

State avg

1.26

EWG Tap Water Atlas utility average (2021–2023) · U.S. utility avg (EWG Atlas sample): 2.85 ppt · MD utility avg: 1.26 ppt

Removes with: RO

Dibromochloromethane

1.81 ppb18.1× health guidelineLower concern

This utility

1.81

U.S. avg

4.14

State avg

1.51

EWG health guideline: 0.1 ppb

THM component linked to cancer and harm to fetal development.

Removes with: RO · Carbon

Nitrate and nitrite

1.08 ppm (EPA limit 10 ppm)Lower concern

This utility

1.08

U.S. avg

1.04

State avg

1.23

EWG Tap Water Atlas utility average (2021–2023) · U.S. utility avg (EWG Atlas sample): 1.04 ppm · MD utility avg: 1.23 ppm

Removes with: RO · Carbon

Nitrate

1.06 ppm (EPA limit 10 ppm)7.6× health guidelineLower concern

This utility

1.06

U.S. avg

1.10

State avg

1.14

EWG health guideline: 0.14 ppm

EWG Tap Water Atlas utility average (2021–2023) · U.S. utility avg (EWG Atlas sample): 1.10 ppm · MD utility avg: 1.14 ppm

Removes with: RO

Fluoride

0.683 ppm (EPA limit 4 ppm)Lower concern

This utility

0.68

U.S. avg

0.49

State avg

0.66

EWG Tap Water Atlas utility average (2021–2023) · U.S. utility avg (EWG Atlas sample): 0.49 ppm · MD utility avg: 0.66 ppm

Removes with: RO · Ion exchange

U.S. and state averages from EWG Tap Water Atlas utilities in our database. For your exact tap, use a ZIP report — home plumbing can differ from utility averages.

Rockville is served by WSSC Water — the same Potomac/Patuxent system that serves Gaithersburg, Bethesda, and Silver Spring.

WSSC finished water meets federal standards; older homes can still add lead from premise plumbing.

EPA UCMR5 monitored PFAS in the WSSC system; kitchen RO is the usual at-the-tap upgrade for PFAS + DBPs.

Compare this report with nearby Montgomery County WSSC cities for the same public water system profile.

PFAS TESTING DATA — EPA UCMR5

Testing period 2023–2025 · Last updated Q1 2026

⚠️

PFAS DETECTED (BELOW MCL)

Max detected: 6.7 ppt · 2 compounds found · 0 EPA MCL violations

Compound

Level (ppt)

EPA MCL

Health Limit

PFPeA

6.7

—

✓ Within

PFHxA

4.8

—

✓ Within

Source: EPA UCMR5 national monitoring dataset · Testing period 2023–2025 · MCL = Maximum Contaminant Level (legally enforceable limit) · Health limit = EPA health advisory threshold

🔔 Get alerts if Rockville's water data changes:

WHICH FILTER TECHNOLOGY WORKS FOR ROCKVILLE?

Reference matrix — not specific brands. NSF-certified carbon blocks, reverse osmosis (NSF 58), and ion-exchange softeners address different contaminants. Product picks below match this profile.

Contaminant

Carbon

Ion exch.

Total Trihalomethanes (TTHMs)

✓

—

Haloacetic Acids (HAA5)

✓

—

Bromodichloromethane

✓

—

Bromochloroacetic acid

✓

—

Dibromochloromethane

✓

—

Nitrate

—

✓

—

TEST YOUR TAP OR FILTER NOW?

Rockvilleutility data is a strong baseline — but lead often comes from your home's pipes, and PFAS can vary by neighborhood. Choose certified lab testing for certainty, or skip straight to NSF-certified filters matched to this profile.

STEP 1 · VERIFY AT YOUR FAUCET

Test before you buy a $300+ filter

SimpleLab Tap Score mail-in panels test PFAS, lead, nitrates, bacteria, and 100+ contaminants at your kitchen tap. Results in about a week — then pick filtration with real numbers, not guesses.

Tap Score City Test — from $89 →

Accredited labs · Best if you have old plumbing, pregnancy, or want proof before installing RO

STEP 2 · FIX IT NOW

Ready to filter based on this report?

Get NSF 58 / NSF 53 picks matched to Rockville's PFAS, lead, and disinfection byproduct profile — reviewed by a 30-year water treatment expert.

Take the 3-question filter quiz →

Best when contaminants are already flagged above and you want the right RO or pitcher today

Clean water splash — certified water filter recommendations

WHAT TO DO ABOUT IT

Based on Rockville's water profile above, here's the exact system we recommend — and why it's right for this water supply specifically.

TOP PICKS FOR ROCKVILLE

⚠ Contaminants detected in local water

Aquasana SmartFlow RO

MOST CERTIFIED

Aquasana · ~$449

WQA Gold Seal + NSF 42/53/58/401. Most certifications of any under-sink RO. Removes 90+ contaminants.

WHY THIS FOR ROCKVILLE · Chosen for Rockville because PFAS was detected at 6.7 ppt in EPA UCMR5 monitoring — above the 4 ppt federal limit — and lead service lines add additional risk. RO removes 99%+ of both at the tap.

Amazon →

AquaTru Under-Sink RO

EASIEST FILTER CHANGE

AquaTru · ~$375

NSF 42/53/58 certified. Quick-change filters, no tools. Compact tankless design, 4-stage filtration.

Amazon →

Not sure which filter is right for you? Take the 3-question quiz →

WATER SYSTEM -- EPA SDWIS

System Name

Washington Suburban Sanitary Commission (WSSC Water)

EPA PWSID

MD0150005

Population Served

67K

State

FREQUENTLY ASKED QUESTIONS

Is Rockville, MD tap water safe to drink?

Yes. Rockville is served by WSSC Water, the same utility serving most of Montgomery County, and its water meets all federal EPA legal standards. As with neighboring Gaithersburg, meeting legal compliance doesn't mean zero health concerns — EPA limits are set based on treatment feasibility, not always the lowest level independent researchers recommend.

Where does Rockville's water come from?

Rockville draws from the same WSSC Water system as most of Montgomery County, sourced primarily from the Potomac and Patuxent Rivers. Because it's the same regional utility and treatment process, water quality across WSSC's Montgomery County service area is broadly similar city to city — the bigger variable is usually the age of a specific home's internal plumbing.

Does Rockville have hard water?

Rockville's water hardness is consistent with the broader WSSC service area, drawing from the same Potomac/Patuxent river sources as Gaithersburg and other Montgomery County communities. A home water test is the most reliable way to confirm your specific hardness level, since local plumbing and neighborhood-level variation can affect readings.

Is there lead risk in Rockville homes?

Rockville has a mix of older and newer housing stock. Homes built before 1986 may still have lead solder or lead-containing fixtures that can leach into water after it leaves the treatment plant, even though WSSC's treated water itself meets federal lead standards. If your home predates 1986, a certified lead filter or water test is a reasonable precaution.

Is there PFAS in Rockville's water?

Rockville is covered by the same UCMR5 PFAS monitoring program as the rest of WSSC's service area. If you want protection beyond current compliance levels, an NSF/ANSI 53 or 58-certified filter rated for PFAS removal is a common recommendation across the WSSC region.

LEAD SERVICE LINE RISK

Does your street have lead pipes?

As of October 2024, all US public water systems must publish a public inventory of their lead service lines — the pipes connecting the water main to your home. Even if your public water system water tests clean at the treatment plant, lead can leach from these pipes into your tap. Homes built before 1986 are most at risk.

EPA Official Service Line Inventory →

Federal LCRR inventory data for Washington Suburban Sanitary Commission (WSSC Water) · PWSID MD0150005

💡 Homes built before 1986 may have lead solder or service lines. A filter certified NSF/ANSI 53 removes lead at the tap regardless of pipe material.

STAY INFORMED

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City-wide data is just the start. Enter your ZIP to see your exact water system's EPA report, PFAS levels, and violation history — then get the right filter for your home.

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