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Not health advice. Contact your local water utility for concerns.
Data from EPA Water Quality Reports. For official information, contact your water utility or health department.
Comprehensive water safety analysis • Updated June 2026
Waltham's water meets EPA standards, though 0 contaminant(s) are elevated above 50% of limits.
•All 3 historical violation(s) in Waltham have been resolved.
Generally Safe. Waltham's tap water meets EPA standards. Score: 84/100.
Want to understand your score better? Learn how scores are calculated →
Is your neighbor's water better? See how Waltham's grade of B+ (84/100) stacks up.
Guides matched to the contaminants found in your water
8 contaminants tested • EPA SDWIS data • Click any contaminant for details
| Contaminant | Level Detected | EPA Limit | % of Limit | Status |
|---|---|---|---|---|
| Total Trihalomethanes | 13.78 ug/L | 80.00 ug/L | 17.2% | Safe |
| Fluoride | 0.659 mg/L | 4.00 mg/L | 16.5% | Safe |
| Nitrite | 0.146 mg/L | 1.00 mg/L | 14.6% | Safe |
| Copper | 0.177 mg/L | 1.30 mg/L | 13.6% | Safe |
| Nitrate | 1.12 mg/L | 10.00 mg/L | 11.2% | Safe |
| Chromium | 0.0085 mg/L | 0.100 mg/L | 8.5% | Safe |
| Haloacetic Acids | 1.66 ug/L | 60.00 ug/L | 2.8% | Safe |
| Mercury | 0 mg/L | 0.0020 mg/L | 0.0% | Safe |
Based on detected contaminants in your water
Removes chlorine, improves taste, and filters many organic compounds. Great starting point.
| Filter Type | Best For | Typical Price |
|---|---|---|
| Reverse Osmosis | Lead, PFAS, arsenic, nitrates (95-99% removal) | $150-300 |
| Under-sink carbon block | Chlorine, VOCs, many organics; some lead/PFAS models | $100-250 |
| Pitcher / faucet carbon | Chlorine, taste; NSF 53 models also reduce lead | $20-50 |
See our full water filter comparison for certified products matched to specific contaminants.
Our data covers your city's water system, but contaminants can vary at the tap. A home water test gives you exact results for your faucet.
Get a Certified Home Water Test — Tap ScoreWe may earn a commission when you purchase through our links, at no extra cost to you. All recommendations are based on our independent analysis of Waltham's water quality data.
Specific to the contaminants found in Waltham's EPA-reported water data
Elevated nitrate levels in Waltham's water pose particular risk to infants under six months. Nitrates can cause methemoglobinemia ("blue baby syndrome"), a condition where the blood cannot carry sufficient oxygen. Symptoms include bluish skin color, shortness of breath, and in severe cases, death. Formula-fed infants are at greatest risk. Pregnant women should also limit nitrate exposure. Boiling water does NOT remove nitrates—it actually concentrates them. Reverse osmosis or distillation systems effectively remove nitrates.
Past violations for Waltham's water system
monitoring
Haloacetic Acids - 2/4/2021
ResolvedMCL
Nitrate - 2/4/2024
Resolvedmonitoring
Lead - 2/4/2021
ResolvedHow to contact your water provider and access official reports
The primary water provider for Waltham is WALTHAM WATER SYSTEM (Public Water System ID: MA119318), serving approximately 68,019 residents. This utility is responsible for treating, testing, and delivering drinking water that meets EPA standards under the Safe Drinking Water Act. As a regulated public water system, it is required to conduct regular testing for over 90 contaminants and publish results in an annual Consumer Confidence Report (CCR) that must be made available to all customers by July 1 each year.
Your water utility is legally obligated to notify customers within 24 hours of any violation that poses an immediate health risk, and within 30 days for less urgent violations. If you are concerned about your water quality, you have the right to request testing data from your utility at any time. For independent verification, you can have your water tested at the tap by a state-certified laboratory. The EPA maintains a list of certified labs by state at epa.gov/dwlabcert. Home testing is particularly important because it captures contamination from your household plumbing that utility testing at distribution points would not detect.
Waltham Water Quality Score
Based on EPA contaminant data and compliance records
Even with good water quality, a filter removes trace contaminants and improves taste.
Best for Fluoride Removal
APEC Reverse Osmosis System
Multi-stage RO removes excess fluoride — the EPA-recommended treatment for fluoride.
Check Price on AmazonNot sure what filter you need?
Get a lab-certified water test to know exactly what's in your tap water.
Test Your Water with Tap ScoreWe may earn a commission when you purchase through our links, at no extra cost to you.
Based on contaminants detected in your water, these resources may be helpful:
Find the right filter for your Waltham water quality needs:
Understand the contaminants that may be present in Waltham's water supply and their health effects.
Matched to the contaminants actually detected in Waltham's water
Elevated nitrates were found in Waltham's water — only reverse osmosis or distillation removes them (boiling does not).
We may earn a commission when you purchase through our links, at no extra cost to you.
Understand your water better with our in-depth guides on contaminants, filtration, and water safety.
Waltham's 84/100 score measured against the Massachusetts average and the national benchmark
Waltham has no contaminants above EPA limits today, though its 3 recorded compliance events are the main reason its grade is B+ rather than higher.
Compared with the Massachusetts average of 82.6, Waltham scores 1.4 points above the state average. Among the 50 Massachusetts cities we track, Waltham ranks #30 — in the middle of the pack statewide.
Against the national benchmark of 80.8/100, Waltham comes in 3.2 points above the national average. The contaminant closest to its limit here is Total Trihalomethanes, measured at 17.2% of the EPA limit, comfortably within the safe range. At the other end, Mercury is its cleanest reading at just 0% of the limit.
For Waltham residents, current contaminant levels are reassuring; the compliance events on record are historical context rather than an active health warning, but they are worth understanding via the EPA databases linked below.
Waltham's drinking water is managed by WALTHAM WATER SYSTEM, which serves approximately 68,019 residents through surface water sources such as rivers, lakes, and reservoirs. Our analysis of 8 tested contaminants reveals a quality score of 84/100, placing Waltham above average compared to other Massachusetts cities.
Waltham's water quality is strong across all tested parameters, with all contaminants well within EPA safety limits. This reflects effective water treatment and well-maintained infrastructure.
Waltham's water system has 3 documented EPA violations in its compliance history. All have since been resolved, indicating the utility has addressed past issues. Compliance history is one of the factors in our scoring methodology.
This report is based on data from the EPA Safe Drinking Water Information System (SDWIS) and the EPA Enforcement and Compliance History Online (ECHO) database. Our scoring algorithm weighs contaminant analysis (50%), compliance history (30%), and infrastructure factors (20%). Data is sourced directly from public EPA records and Consumer Confidence Reports. We are an independent resource with no affiliation to water utilities or government agencies. Learn more about our methodology.
Common questions from Waltham, Massachusetts residents about their drinking water
Yes, Waltham's tap water generally meets EPA safety standards with a quality score of 84/100 (Grade B+). All 8 tested contaminants are within legal limits, indicating the water treatment process is effective. However, water quality at your faucet can differ from what leaves the treatment plant due to your home's plumbing. Older homes built before 1986 may have lead solder or galvanized pipes that introduce contaminants. Even with a good score, a basic water filter can improve taste and provide extra peace of mind.
Waltham's water has been tested for 8 contaminants spanning inorganic chemicals, disinfection byproducts, organic compounds, radionuclides, and microorganisms. All tested contaminants are within safe limits, with 8 contaminants well below 50% of their respective EPA Maximum Contaminant Levels.' See the full contaminant breakdown table above for detailed measurements and EPA limit comparisons.
Waltham has a water quality score of 84/100, earning a grade of B+. This score is calculated using EPA SDWIS data and weighs three factors: contaminant levels (50% of score), regulatory compliance history (30%), and infrastructure factors (20%). The national average is approximately 72/100. Waltham's score of 84 is 12 points above the national average, indicating above-average water quality management. Learn more about how scores are calculated.
An activated carbon filter would be suitable for Waltham residents. Based on the contaminant profile, a carbon filter will effectively reduce chlorine taste, disinfection byproducts, and many organic compounds. Options range from pitcher filters ($20-40) to under-sink systems ($100-250). Even in cities with good water quality, a filter provides an additional layer of protection against contaminants that may enter water from your home's plumbing. View our water filter comparison guide for specific product recommendations.
Waltham's primary water system, WALTHAM WATER SYSTEM (PWS ID: MA119318), sources water from surface water such as rivers, lakes, or reservoirs. Surface water sources are more susceptible to contamination from agricultural runoff, industrial discharge, and stormwater, which is why extensive multi-step treatment including coagulation, sedimentation, filtration, and disinfection is required. This system serves approximately 68,019 residents.
Lead testing in Waltham shows levels within EPA action level guidelines. However, lead contamination is primarily a household plumbing issue rather than a water source issue. Lead can enter water from lead service lines, lead solder (used in homes built before 1986), and brass fixtures. Even if your city's water is lead-free at the treatment plant, your home's plumbing may introduce lead. Homes built before 1986 should consider testing their water at the tap. Running cold water for 30 seconds before drinking is always a good practice.
Yes, Waltham's water system has 3 documented EPA violations in its compliance history. All violations have been resolved, indicating the utility has taken corrective action. Violations can include exceeding contaminant limits, failure to conduct required testing, or failure to properly notify customers. Water utilities are required by the Safe Drinking Water Act to address violations and notify affected customers. You can look up the full violation history through the EPA's ECHO database or by contacting your water utility directly.
There are several options for testing your water in Waltham. For the most comprehensive results, use a state-certified laboratory (find one at epa.gov/dwlabcert). Home test kits like Tap Score provide EPA-certified lab analysis with easy-to-understand results. Basic test strips available at hardware stores can screen for common parameters like chlorine, pH, hardness, and lead, though they are less accurate than laboratory testing. You can also request the latest testing data directly from WALTHAM WATER SYSTEM. Testing at your tap is important because it captures contamination from your household plumbing that city-level monitoring at distribution points does not detect.