Water Quality in Portsmouth, NH: 12 Violations — Grade C
Grade C · Score 66/100 · 5 water systems · Updated 2026-05-03
Portsmouth's water has moderate compliance issues. Residents in affected areas should consider filtration.
Data: EPA Safe Drinking Water Information System (SDWIS) Last verified: 2026-05-03
Compliance records maintained by the EPA for Portsmouth, NH log 12 violations — accumulated reportable events drawn from every local utility in the SDWIS national tracking system.
Water Quality by ZIP Code in Portsmouth
Water quality varies across Portsmouth's 4 ZIP codes. Check your specific ZIP for detailed contaminant data.
| ZIP Code | Grade | Score | Violations | Health | |
|---|---|---|---|---|---|
| 03801 | B | 77 | 3 | 1 | View report → |
| 03802 | B | 82 | 3 | 1 | View report → |
| 03803 | B | 82 | 3 | 1 | View report → |
| 03804 | B | 82 | 3 | 1 | View report → |
Water Quality Overview
Portsmouth, New Hampshire receives a water quality grade of C with an overall score of 66 out of 100, based on EPA compliance data from the Safe Drinking Water Information System (SDWIS).
The 5 water systems serving Portsmouth have accumulated 12 EPA violations, including 4 health-based violations. These violations are tracked across 4 ZIP codes serving approximately 44,142 people.
What Grade C Means
A grade of C indicates moderate compliance issues. Portsmouth's water systems have some violations that warrant attention. While the water may still be safe for most people, residents in affected ZIP codes should consider additional testing or filtration.
Lead Levels
The average 90th percentile lead level across Portsmouth water systems is 0.0010 mg/L — within EPA limits. No ZIP codes exceed the EPA lead action level.
With 76% of homes built before 1986, Portsmouth has a higher-than-average risk of lead from older plumbing. Lead solder was banned in 1986, and homes built before this date may have lead in pipes, solder joints, or fixtures.
Radon Risk
Portsmouth is in EPA Radon Zone 1 (High risk). The EPA recommends all homes in Zone 1 areas be tested for radon. Radon is the second leading cause of lung cancer after smoking.
Water Systems Serving Portsmouth
Portsmouth is served by 5 community water systems regulated under the Safe Drinking Water Act. These systems collectively serve approximately 44,142 people across 4 ZIP codes.
Each water system is identified by a Public Water System ID (PWSID) and is required to:
- Test for over 90 regulated contaminants on a regular schedule
- Report results to the EPA and state regulators
- Issue an annual Consumer Confidence Report (CCR) to all customers
- Take corrective action when violations occur
The EPA has taken 40 enforcement actions against water systems serving Portsmouth. Enforcement actions range from informal compliance assistance to formal orders and penalties.
How to Check Your Water in Portsmouth
Enter your ZIP code on ZipCheckup to see your specific water system data, including contaminant levels, violation history, and safety scores
Request your CCR — your water utility must provide an annual Consumer Confidence Report with detailed test results for all monitored contaminants
Get a home test — certified kits cost $20–$50 and test for lead, bacteria, and common contaminants. Professional lab tests ($150–$400) cover a broader panel
Consider filtration — NSF-certified filters can remove specific contaminants. Reverse osmosis removes the broadest range; activated carbon is effective for chlorine and many organics
Check for advisories — monitor your local utility website and local news for boil water advisories or system alerts
Contaminants Detected in Portsmouth Water Systems
The following contaminants have been detected or caused violations across Portsmouth's water systems:
| Contaminant | Category | MCL | Violations | ZIPs Affected | Health-Based |
|---|---|---|---|---|---|
| Stage 1 DBP Rule | Treatment Technique | N/A | 8 | 4 | No |
MCL = Maximum Contaminant Level (EPA enforceable standard). Health-based violations indicate levels that may pose direct health risks.
EPA Enforcement History
The EPA and state regulators have taken 10 enforcement actions against water systems serving Portsmouth. Recent actions:
| Date | Action Type |
|---|---|
| 2024-04-02 | State Informal Action |
| 2024-04-02 | State Order Extension |
| 2023-12-08 | State Order Extension |
| 2023-10-11 | State Informal Action |
| 2023-10-09 | State Informal Action |
| 2023-10-09 | State Informal Enforcement |
| 2022-07-19 | State Order Extension |
| 2022-01-19 | State Order Extension |
| 2022-01-14 | State Informal Action |
| 2021-12-20 | State Informal Action |
Enforcement actions range from informal compliance assistance to formal orders and penalties. The most recent action was on 2024-04-02.
Portsmouth vs. Nearby New Hampshire Cities
How Portsmouth's water quality compares to similar cities in New Hampshire:
| City | Grade | Violations | Systems | Population |
|---|---|---|---|---|
| Portsmouth | C | 12 | 5 | 44,142 |
| Concord | D | 84 | 5 | 46,733 |
| Monroe | B | 9 | 5 | 35,983 |
| Hampton | B | 10 | 5 | 34,710 |
Water Quality by ZIP Code in Portsmouth
Water quality varies across Portsmouth's ZIP codes. The table below shows the worst-scoring and best-scoring areas:
| ZIP Code | Score | Grade | Violations | Health-Based |
|---|---|---|---|---|
| 03801 | 77 | B | 3 | 1 |
| 03802 | 82 | B | 3 | 1 |
| 03803 | 82 | B | 3 | 1 |
| 03804 | 82 | B | 3 | 1 |
Common Questions About Portsmouth Water
These are the most common questions residents search for about water quality in Portsmouth, New Hampshire:
Is Portsmouth water hard or soft? Water hardness varies by source. Portsmouth's 5 water systems use multiple sources. Check your ZIP code report for specific hardness data.
Can I drink Portsmouth tap water? Portsmouth's water receives a grade of C (66/100). There are 4 health-based violations — consider filtration.
What is the best water filter for Portsmouth? A NSF/ANSI 53-certified filter for lead removal is a good general choice. See our Water Filter Matcher for personalized recommendations.
Portsmouth vs. New Hampshire Average
Understanding how Portsmouth compares to the broader New Hampshire average helps contextualize your local water quality. Factors like water source, treatment methods, and infrastructure age all contribute to differences between cities in the same state.
To see how individual neighborhoods compare, check the ZIP code reports below — water quality can vary significantly even within Portsmouth.
ZIP Codes in Portsmouth
Portsmouth spans 4 ZIP codes. The ZIP with the lowest water quality score is 03801. Each ZIP code has its own water quality profile based on the specific water system serving that area. Check each ZIP code for detailed contaminant data, violation history, and system information.
Data Sources
- Water quality: EPA Safe Drinking Water Information System (SDWIS)
- Lead/copper: EPA Lead and Copper Rule sampling data
- Radon: EPA Map of Radon Zones
- Enforcement: EPA ECHO database
- Filter recommendations: NSF/ANSI certified products
Updated daily.