Haloacetic Acids
Approaching LimitDetected level
38.8112 ug/L
0%EPA Limit (60 ug/L)
65% of EPA limit
Health effects: Disinfection byproducts associated with increased cancer risk and potential reproductive effects.
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Tap Water Safety Report for Lewiston, Idaho
Lewiston, Idaho tap water scored 71/100 (B-) based on EPA data. While the water meets minimum EPA standards, 2 contaminant(s) are at elevated levels worth monitoring.
Overall Score
71/100
Grade: B-
Contaminants Tested
9
All within limits
EPA Violations
1
All resolved
Water Source
surface
Surface water
Population Served
36,802
residents
Water Systems
1
serving this area
2 contaminant(s) are approaching EPA limits and should be monitored.
Detected level
38.8112 ug/L
65% of EPA limit
Health effects: Disinfection byproducts associated with increased cancer risk and potential reproductive effects.
Detected level
0.0076 mg/L
51% of EPA limit
Health effects: Developmental delays in children, kidney damage, and high blood pressure in adults. No safe level of lead exposure exists.
Based on Lewiston's water quality data, here are our specific recommendations:
With 2 contaminant(s) at elevated levels, a certified pitcher or faucet filter provides an affordable layer of protection. Look for NSF/ANSI certification.
City water reports reflect water leaving the treatment plant. Your home pipes may add contaminants, especially in older buildings. Test at the tap for the most accurate picture.
How contaminant levels compare to EPA limits (50% of overall score)
EPA violation history and enforcement actions (30% of overall score)
Water system infrastructure and source quality (20% of overall score)
Lewiston's water scored 71/100 with 2 contaminant(s) at elevated levels. Children are more vulnerable to water contaminants due to their lower body weight and developing systems. We recommend using a certified water filter for any water used for baby formula, cooking for children, or children's drinking water. A pitcher filter with NSF certification is an affordable first step.
Lewiston's water has been tested for 9 contaminants. None currently exceed EPA maximum contaminant levels. The most notable detections include: Haloacetic Acids (38.8112 ug/L, EPA limit: 60 ug/L — 65% of limit); Lead (0.0076 mg/L, EPA limit: 0.015 mg/L — 51% of limit); Nitrite (0.4881 mg/L, EPA limit: 1 mg/L — 49% of limit); Arsenic (0.0048 mg/L, EPA limit: 0.01 mg/L — 48% of limit); Chromium (0.048 mg/L, EPA limit: 0.1 mg/L — 48% of limit). The water system has no active EPA violations. Water quality can vary seasonally and by neighborhood, so home testing provides the most accurate picture for your specific tap.
Yes, we recommend filtering your water in Lewiston. With a score of 71/100 and 2 contaminant(s) at elevated levels, a certified water filter adds a meaningful layer of protection. A faucet-mounted or pitcher filter with NSF/ANSI 53 certification is a good starting point. For more thorough contaminant removal, consider an under-sink reverse osmosis system, especially if you have specific concerns about Haloacetic Acids.
Lewiston's water quality score of 71/100 (B-) is 1 points below the national average of 72. The city's water comes from surface water sources like rivers and reservoirs. While the water meets minimum federal standards, there is room for improvement compared to top-performing cities. You can see how Lewiston compares to nearby cities in our state rankings.
Detailed contaminant data, violation history, and water system information for Lewiston.
Find the best water filter for Lewiston based on detected contaminants and your budget.
See how Lewiston compares to other cities across Idaho.
See how Lewiston ranks among all cities in the US for water quality.
Data Disclaimer
This report is based on publicly available EPA data and water quality test results. Water quality can vary by neighborhood, building age, and season. This information is for educational purposes and should not replace professional water testing. If you have specific health concerns about your water, contact your local water utility or a certified water testing laboratory. Last data update: February 2, 2026.