Data: EPA Safe Drinking Water Information System (SDWIS) Last verified: 2026-05-03

Reviewing EPA compliance files for Waltham, MA surfaces 8 documented water violations — each categorized by violation type and linked to the utility that drew the federal citation.

Water Quality by ZIP Code in Waltham

Water quality varies across Waltham's 4 ZIP codes. Check your specific ZIP for detailed contaminant data.

ZIP Code	Grade	Score	Violations	Health
02451	C	59	2	0	View report →
02452	C	59	2	0	View report →
02453	C	64	2	0	View report →
02454	C	65	2	0	View report →

Water Quality Overview

Waltham, Massachusetts receives a water quality grade of C with an overall score of 62 out of 100, based on EPA compliance data from the Safe Drinking Water Information System (SDWIS).

The 2 water systems serving Waltham have accumulated 8 EPA violations (all monitoring/reporting type). These violations are tracked across 4 ZIP codes serving approximately 65,258 people.

What Grade C Means

A grade of C indicates moderate compliance issues. Waltham'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 Waltham water systems is 0.0019 mg/L — within EPA limits. No ZIP codes exceed the EPA lead action level.

With 75% of homes built before 1986, Waltham 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

Waltham 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 Waltham

Waltham is served by 2 community water systems regulated under the Safe Drinking Water Act. These systems collectively serve approximately 65,258 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 12 enforcement actions against water systems serving Waltham. Enforcement actions range from informal compliance assistance to formal orders and penalties.

How to Check Your Water in Waltham

1. Enter your ZIP code on ZipCheckup to see your specific water system data, including contaminant levels, violation history, and safety scores

2. Request your CCR — your water utility must provide an annual Consumer Confidence Report with detailed test results for all monitored contaminants

3. 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

4. Consider filtration — NSF-certified filters can remove specific contaminants. Reverse osmosis removes the broadest range; activated carbon is effective for chlorine and many organics

5. Check for advisories — monitor your local utility website and local news for boil water advisories or system alerts

EPA Enforcement History

The EPA and state regulators have taken 3 enforcement actions against water systems serving Waltham. Recent actions:

Enforcement actions range from informal compliance assistance to formal orders and penalties. The most recent action was on 2025-04-09.

Waltham vs. Nearby Massachusetts Cities

How Waltham's water quality compares to similar cities in Massachusetts:

Water Quality by ZIP Code in Waltham

Water quality varies across Waltham's ZIP codes. The table below shows the worst-scoring and best-scoring areas:

Common Questions About Waltham Water

These are the most common questions residents search for about water quality in Waltham, Massachusetts:

Is Waltham water hard or soft? Water hardness varies by source. Waltham's 2 water systems use multiple sources. Check your ZIP code report for specific hardness data.

Can I drink Waltham tap water? Waltham's water receives a grade of C (62/100). No health-based violations have been recorded, but home testing is always recommended.

What is the best water filter for Waltham? A NSF/ANSI 53-certified filter for lead removal is a good general choice. See our Water Filter Matcher for personalized recommendations.

Waltham vs. Massachusetts Average

Understanding how Waltham compares to the broader Massachusetts 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 Waltham.

ZIP Codes in Waltham

Waltham spans 4 ZIP codes. The ZIP with the lowest water quality score is 02451. 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.