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EPA SDWIS City OverviewWater Testing & Safety Guide

Longmont, CO Water Quality Testing & Safety Report

EPA compliance records, water testing guidelines, and hardness metrics for all 4 ZIP codes in Longmont, Colorado

Quick EPA Verified Summary

Is Tap Water Safe to Drink in Longmont, CO?

Tap water in Longmont, CO receives an EPA Safety Grade of C (62/100) due to 0 health-based violation(s) and elevated lead risk. While treated by local utilities, residents are advised to test tap water and use an NSF/ANSI 53 certified filter for drinking and cooking.

Average Score

62/100

Health Violations

0

Water Hardness

Moderately Hard

105 mg/L (6.1 GPG)

High Lead Risk

1

of 4 ZIP codes

C

About Tap Water in Longmont, CO

Drinking water in Longmont, CO receives an average water quality grade of C (score: 62/100) across its 4 ZIP codes. Safe Drinking Water Act compliance monitoring is managed by local utilities including City of Longmont.

⚠ Lead Risk Alert: Some ZIP codes in Longmont are rated High or Very High for lead exposure risk based on EPA data. Search your specific ZIP code for a detailed lead level report.

Water Quality Testing in Longmont, CO

Tap Water & Well Water Testing Recommendations

Testing your drinking water in Longmont confirms whether contaminants like lead, nitrates, bacteria, and PFAS are entering your home. While municipal utilities test water before distribution, private plumbing and private well systems require homeowner testing.

Tap Water Testing Checklist

  • 1.Identify your plumbing age: Homes built before 1986 in Longmont may have lead solder or lead service lines.
  • 2.Request your utility's latest Consumer Confidence Report (CCR) for annual municipal baseline data.
  • 3.Use an EPA-certified laboratory or state-certified test kit for precision lead and PFAS detection (standard DIY strips cannot reliably measure trace heavy metals).
  • 4.Collect a "first draw" sample: Test water that has sat motionless in pipes for at least 6 hours to check for plumbing corrosion.

Private Well Water Testing Checklist

  • •Private wells in CO are not monitored by the EPA or Colorado Department of Public Health and Environment — testing is 100% the homeowner's responsibility.
  • •Annual Test: Screen for Total Coliform Bacteria, E. coli, Nitrates/Nitrites, and pH every spring.
  • •Comprehensive Test (Every 3-5 Years): Test for heavy metals (Lead, Arsenic, Uranium), Volatile Organic Compounds (VOCs), and Hardness.
  • •Post-Disruption Testing: Immediately test well water following heavy floods, local construction, agricultural runoff, or sudden taste/odor changes.

Critical Water Testing Parameters for Longmont Residents

ParameterHealth ReasonEPA Limit / Standard
Lead (Pb)Plumbing corrosion; dangerous neurotoxin for children15 ppb (Action Level) / 0 ppb Goal
Total Coliform & E. ColiBacterial contamination from sewage or surface runoff0 mg/L (Zero Tolerance)
Nitrates / NitritesFertilizer and septic tank seepage; causes blue baby syndrome10 mg/L (MCL)
Water Hardness (Ca & Mg)Affects appliance lifespan, scale buildup, and skin hydrationModerate (~100 mg/L)
PFAS ("Forever Chemicals")Industrial non-stick chemicals linked to metabolic and immune issues4.0 ppt (EPA 2024 Rule)
State Regulatory Oversight: Environmental standards and certified water lab registries in CO are maintained by the Colorado Department of Public Health and Environment.

Water Quality by ZIP Code — Longmont, CO

Showing 4 of 4 monitored ZIP codes in Longmont

C
80502

Longmont, CO

Score: 65/100✓ Clean Record
C
80504

Longmont, CO

Score: 64/100✓ Clean Record
C
80501

Longmont, CO

Score: 59/100✓ Clean Record
C
80503

Longmont, CO

Score: 59/100✓ Clean Record

All Longmont, CO ZIP Code Reports (4 Total)

80502805048050180503

Nearby Cities Water Quality & Testing in Colorado

Compare tap water safety, EPA test scores, and water hardness across neighboring cities in Colorado:

Agate, CO1 ZIP code
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Aguilar, CO1 ZIP code
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Akron, CO1 ZIP code
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Alamosa, CO2 ZIP codes
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Allenspark, CO1 ZIP code
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Alma, CO1 ZIP code
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Almont, CO1 ZIP code
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Amherst, CO1 ZIP code
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Frequently Asked Questions — Longmont Water Quality & Testing

Is tap water safe to drink in Longmont, CO?+
Tap water in Longmont has a grade of C, indicating compliance concerns in recent years. Families with young children or pregnant women should consider using a certified NSF/ANSI 53 water filter for drinking and cooking.
How do I test water quality in Longmont, CO?+
To test water quality in Longmont, you can order an EPA-compliant drinking water test kit or submit samples to a state-certified environmental testing laboratory in CO. Testing is especially recommended for homes built before 1986 (to check for lead in plumbing) and for properties with private well systems.
Should I test private well water in Longmont?+
Yes. Unlike municipal tap water, private wells in Longmont, CO are not monitored or regulated by the EPA or local utilities. Private well owners are responsible for testing their water annually for coliform bacteria and nitrates, and every 3 to 5 years for heavy metals (lead, arsenic) and volatile organic compounds.
How hard is the tap water in Longmont?+
Tap water in Longmont is classified as Moderately Hard with an estimated average hardness of 105 mg/L (6.1 GPG). A water softener is generally optional.
What is the water quality score for Longmont?+
The average water quality score across 4 ZIP codes in Longmont, CO is 62/100. Scores are derived from EPA violation history, lead levels, enforcement actions, and infrastructure risk indicators. Individual ZIP codes may vary — search your specific ZIP above for a personalized report.
Does Longmont have lead in its tap water?+
1 out of 4 ZIP codes in Longmont are rated High or Very High for lead exposure risk. Older homes built before 1986 may have lead service lines or plumbing fixtures. Residents should run their tap for 30 seconds before use and consider a certified NSF/ANSI 53 lead filter.
Where does Longmont's tap water come from?+
Tap water in Longmont, CO primarily comes from surface water. Surface water systems treat water from rivers, lakes, or reservoirs using filtration, sedimentation, and disinfection before it reaches your tap.

Looking for water quality reports in other cities in Colorado?

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