EPA SDWIS ~155K water systems EPA + UCMR5

Heptachlor

Compiled by PlainWater Editorial, Drinking Water Quality Editorial Team · May 15, 2026

EPA SDWIS quarterly extract data for this analyte. Detection counts and health-based violation counts reflect the most recent federal release.

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EPA contaminant code: 2065

Total Violations

45,763

Systems Affected

8,396

Health-Based %

Most Affected State

What this means

Heptachlor appears in EPA SDWIS with 45,763 recorded violations across 8,396 public water systems. Of those, 0% are classified as health-based, meaning the reading exceeded a federally enforceable Maximum Contaminant Level or a treatment-technique requirement rather than a monitoring or reporting lapse. Health-based violations are the subset that trigger formal corrective action and public notification, so the share is a useful signal of real-world exposure risk rather than paperwork drift. State-level concentration data is not consistently reported for this contaminant, so regional interpretation should lean on the system table below rather than state aggregates. Utilities listed below are ranked by cumulative violation count, so a higher rank reflects persistence in the record rather than a single spike; readers comparing systems should consider population served alongside violation count to gauge how many households were actually exposed.

Violation Type Split

Heptachlor violations broken down by EPA classification.

Health-based (0%) Monitoring/Reporting (100%)

Health-based violations indicate the contaminant exceeded an EPA Maximum Contaminant Level (MCL) or treatment-technique requirement; monitoring/reporting violations are procedural.

Most Affected Water Systems

System	State	Violations	Population
Pinnacle Water Association	WV	188	85
Salem Heights Estate	PA	160	62
Congregation Ohr Menachem	PA	149	30
Coal Mountain Water	WV	149	80
Lewis Co Water Dist #2	WA	126	1,983
Skyview Estates	IL	124	56
Prague	OK	111	2,395
Marble Water System	WA	105	94
Frankfort Psd	WV	100	6,747
Dabob Cove Community	WA	94	24
27 Maple Drive	CT	88	38
Aqua PA Sun Valley	PA	79	120
Vista del Rio Mobile Home Park	WA	75	352
Neshaminy Manor Center	PA	74	2,100
Springhill Park Subdivision	MT	72	90
PA American Audubon	PA	72	8,200
Christ Mission Lutheran Church	IL	70	150
Willow Springs MHP	IN	66	25
Helena RV and Mobile Home Park	MT	66	250
Save a Pet	IL	64	50
Oilton	OK	64	1,435
Seneca Trail Christian Academy	WV	64	100
Malta City Of	MT	63	1,800
Congregation Beth Judea	IL	62	25
Ambler Boro Water Dept	PA	60	20,000
Paradise Stream Resor	PA	60	774
Lewis River Golf Course	WA	60	300
Taleem Ul Haq	IL	56	100
Tooele City Water System	UT	56	37,100
Taggares Fruit Co	WA	55	152

Drinking Water Guides

Understanding Water Quality Data

What EPA SDWIS tracks, how violations are classified, and what MCLs mean.

PFAS in Drinking Water

What forever chemicals are, EPA testing results, and 2024 standards.

Is My Water Safe?

How to assess your local water quality and when to take precautions.

Frequently Asked Questions

What is Heptachlor in drinking water? ▼

Heptachlor is a contaminant tracked by the EPA under the Safe Drinking Water Act. It has caused 45,763 violations across 8,396 public water systems nationwide. 0% of these violations are health-based, meaning the contaminant exceeded Maximum Contaminant Levels (MCLs) or treatment technique requirements.

How many water systems have Heptachlor violations? ▼

8,396 public water systems across the United States have at least one Heptachlor violation recorded in the EPA SDWIS database.

Are Heptachlor violations dangerous? ▼

0% of Heptachlor violations are health-based, meaning the contaminant level exceeded safe limits set by the EPA. Health-based violations require corrective action by the water system. Not all violations indicate immediate health risk, but they signal that water quality standards were not met.

Which state has the most Heptachlor violations? ▼

State-level breakdown data is not available for this contaminant.

Where does this contaminant data come from? ▼

All violation data comes from the EPA Safe Drinking Water Information System (SDWIS), which tracks compliance for all public water systems regulated under the Safe Drinking Water Act. SDWIS records violations including Maximum Contaminant Level (MCL) exceedances, treatment technique failures, and monitoring/reporting issues.

Data Sources

Contaminant violation data from the EPA Safe Drinking Water Information System (SDWIS). Violations are categorized as health-based (Maximum Contaminant Level exceedances, treatment technique failures) or monitoring/reporting violations.

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Data sourced from EPA SDWIS and UCMR5 PFAS monitoring data. See our methodology for details. Retrieved and formatted by PlainWater Editorial

Disclaimer: This information is provided for informational purposes only and does not constitute professional advice. Data is sourced from the EPA Safe Drinking Water Information System (SDWIS). Consult a qualified professional before making decisions based on this data.

Read our methodology - how this data is sourced, computed, and verified.

Every figure on PlainWater is rendered directly from EPA SDWIS drinking-water data, no number is typed in by an editor. This page draws directly on EPA SDWIS data, no figure is typed in by an editor. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error.