LEWISTOWN, Montana Tap Water Quality

6,078 people served · 4 water systems

Failing

LEWISTOWN, Montana is a small town with 6,078 residents served by 4 public water systems. Water service covers ZIP code 59457.

LEWISTOWN has accumulated a significant number of EPA health-based violations. Reviewing the contaminants involved, requesting your utility's Consumer Confidence Report, and using certified point-of-use filtration is strongly advisable.

EPA reporting identifies Mercury (Inorganic) among the regulated contaminants associated with LEWISTOWN's recent health-based violations. Each contaminant has different sources, health implications, and recommended mitigation steps — links to the full EPA reference for each are listed alongside the violation history below.

Last updated: 2026-05-18 · Source: EPA SDWIS

Location

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Centered on ZIP-code centroids of water systems serving this city.

ZIP Codes Served

59457

Health-Based Violations (Last 5 Years)

EPA Maximum Contaminant Level exceedances reported by water systems serving LEWISTOWN. Each entry explains the contaminant, the health risk, and recommended precautions, and links to a full guide.

Mercury (Inorganic)chemical

EPA Code 1038 · Maximum Contaminant Level Exceedance

122

violations

EPA Limit

0.002 mg/L

Last Reading

10.7 MG/L

First Reported

Apr 2021

Most Recent

Oct 2025

What this violation means

Inorganic mercury in drinking water primarily damages kidneys. Most mercury exposure for Americans comes from fish (methylmercury), but localized water contamination occurs near refineries, coal-burning plants, and certain landfills.

Recommended precautions

→Reverse osmosis and distillation remove inorganic mercury.
→Activated carbon adsorption works for mercury but capacity is limited.
→Test private wells near industrial sites or landfills.

Read the complete guide to Mercury (Inorganic)

Source: EPA Safe Drinking Water Information System (SDWIS). Health-based violations only. Older violations may have been resolved; check your utility's most recent Consumer Confidence Report for current status.

Water Systems Serving LEWISTOWN

SPRING CREEK COLONY LEWISTOWN

PWSID: MT0000433

48 served

DEERFIELD HUTTERITE COLONY

PWSID: MT0000431

51 served

KING RANCH COLONY

PWSID: MT0000432

56 served

122 violations

LEWISTOWN CITY OF

PWSID: MT0000271

5,923 served

What Can You Do?

✅ Request your utility's annual Consumer Confidence Report (CCR) — required by law.
✅ Use an NSF-certified water filter if violations involve lead, arsenic, or PFAS.
✅ Run cold water for 30 seconds before drinking if you have older plumbing (reduces lead).
✅ Check back monthly — we update data from the EPA every 30 days.

About this data

This overview reflects EPA SDWIS data published as of 2026-05-18. It covers active Community Water Systems (CWS) that exceeded federal Maximum Contaminant Levels during the past five-year EPA reporting window. For up-to-the-minute information, request a current Consumer Confidence Report from your utility, or review the EPA's public dashboard.

Frequently Asked Questions

Is LEWISTOWN, Montana tap water safe to drink?▼

This city's water had numerous EPA violations in the last 5 years. Consider filtered water.

How many EPA violations does LEWISTOWN have?▼

LEWISTOWN has 122 EPA health-based water violations in the last 5 years across 4 water systems serving 6,078 people.

What contaminants have been found in LEWISTOWN water?▼

The following EPA-regulated contaminants have been detected: 1038. View details about each contaminant, health effects, and recommended precautions above in the violations table.

Should I use a water filter in LEWISTOWN?▼

Using an NSF-certified water filter is recommended if your area has violations involving lead, arsenic, or PFAS. For other contaminants, consult your local water utility. Check the annual Consumer Confidence Report (CCR) for detailed guidance.

What should I do if there are violations in LEWISTOWN?▼

Request your water utility's annual Consumer Confidence Report (CCR), which is required by the EPA. Follow the utility's guidance on boil water advisories. Run cold water for 30 seconds before drinking if you have older plumbing. Use an NSF-certified filter if needed based on your water system's violations.