Water systems

U.S. Water Systems & Water Quality Records

EPA water systems with supply relationships, PFAS and lithium observations, lead and copper results, and dated compliance records.

Primary rows: 434,040
Primary fields: 49
Coverage: US
Source snapshot: Oct 3, 2026

Each primary row: One reported water system in a captured SDWIS reporting quarter, including inactive systems.

Sample data

Download sample

100 sample rows as CSV · all 49 primary fields.

Row
1	407056	2026Q2	NC0136486	LATIMORE MHP	NC	04	01-01	12-31	I	01/01/1980	CWS	—	—	GW	—	P	28	1	1	1	1	1	State	GW	N	N	N	7	Y	—	—	—	DALLAS	28034	US	03/12/1980	11/20/2004	NC	—	—	—	—	—	—	—	—
2	411652	2026Q2	CA1504000	FAMOSO NUT COMPANY	CA	09	01-01	12-31	A	—	NTNCWS	—	—	GW	—	P	80	1	1	1	1	1	State	GW	Y	N	N	5	Y	661-399-9697	32331 FAMOSO ROAD	—	MCFARLAND	93250	US	09/02/2015	06/22/2026	CA	—	—	—	—	—	—	—	—
3	127111	2026Q2	ND4711097	JAMESTOWN REST AREA NORTH UNIT	ND	08	01-01	12-31	I	05/01/1990	TNCWS	—	—	GW	—	—	300	1	1	1	1	2	State	GW	N	N	N	1	Y	—	—	—	JAMESTOWN	58401	US	03/05/1980	07/25/1995	ND	—	—	—	—	—	—	—	—
4	153012	2026Q2	PA3540488	CHRIST CHURCH UCC	PA	03	01-01	12-31	I	05/10/1985	TNCWS	—	—	GW	—	P	75	1	1	1	1	1	State	GW	N	N	N	1	Y	570-682-8148	%DAVID C OTTO RD 1	—	HEGINS	17938	US	03/29/1980	06/15/2026	PA	—	—	—	—	—	—	—	—
5	215738	2026Q2	FL6296036	DOVER PENTECOSTAL HOLINESS CHURCH	FL	04	01-01	12-31	A	—	TNCWS	—	—	GW	—	P	45	1	1	1	1	1	State	GW	Y	N	N	2	Y	813-659-1301	PO BOX 1019	—	DOVER	33527	US	12/03/1996	05/18/2026	FL	—	—	—	—	—	—	—	—

— Empty cell · does not mean zero or no[] / {} Empty collection0 / false Recorded values

Download field definitions (CSV)

Download sample documentation (ZIP)

Included data

434,040 water-system records link to facility inventories, service areas, geographic references and reported seller relationships.
1,992,002 UCMR5 analyte observations retain sample identifiers, qualifiers, reporting levels and units; lead and copper results are supplied separately.
Compliance and enforcement relationships with periods beginning in 2020 onward accompany source reference-code definitions.

What’s in the package

water_systems.csv434,040 rows · 49 fields
ucmr_observations.csv1,992,002 rows · 25 fields
One published analyte/sample observation with result qualifier.
facilities.csv1,554,832 rows · 20 fields
One reported facility source row for a water system and reporting quarter.
supply_relationships.csv49,222 rows · 11 fields
One reported facility row with a seller PWSID; availability does not establish actual water flow.
geographic_areas.csv578,198 rows · 12 fields
One reported geographic area served by a water system in a reporting quarter.
service_areas.csv422,464 rows · 7 fields
One reported service-area classification for a water system in a reporting quarter.
lead_copper_results.csv927,415 rows · 16 fields
One reported lead/copper sample and summary-result source row, with dates, qualifier and unit.
violation_enforcement.csv2,254,413 rows · 39 fields
One published violation/enforcement relationship row; several actions can repeat the same violation.
reference_codes.csv2,376 rows · 4 fields
One published source-code description within its value-type namespace.
ucmr_additional_elements.csv436,993 rows · 7 fields
One retained coded additional-data response for a facility/sample point and sampling event.
ucmr_zip_areas.csv31,429 rows · 3 fields
One published UCMR water-system-to-ZIP relationship.

Companion table fields

ucmr_observations.csv25 fields

Field	Definition & format
Source row number `source_row_number`	One-based data-row ordinal in the exact source member. Type integer Format Derived count or ordinal Blank cells Not reported, not applicable or unavailable Populated · full table 1,992,002 / 1,992,002 (100.00%)
PWSID `pwsid`	Public water system identifier; combines with facility and sample identifiers to link related records. Type text Blank cells Not reported, not applicable or unavailable Populated · full table 1,992,002 / 1,992,002 (100.00%)
UCMR system name `pwsname`	Public water system name in the UCMR record. Type text Blank cells Not reported, not applicable or unavailable Populated · full table 1,992,002 / 1,992,002 (100.00%)
Size `size`	Reported size category of the public water system. Type text Blank cells Not reported, not applicable or unavailable Populated · full table 1,992,002 / 1,992,002 (100.00%)
Facility ID `facility_id`	Facility identifier within the public water system; not nationally unique on its own. Type text Blank cells Not reported, not applicable or unavailable Populated · full table 1,992,002 / 1,992,002 (100.00%)
Facility name `facility_name`	Name of the sampled water-system facility. Type text Blank cells Not reported, not applicable or unavailable Populated · full table 1,992,002 / 1,992,002 (100.00%)
Facility water type `facility_water_type`	Water source type reported for the sampled facility. Type text Blank cells Not reported, not applicable or unavailable Populated · full table 1,992,002 / 1,992,002 (100.00%)
Sample point ID `sample_point_id`	Sample-point identifier within the water-system facility. Type text Blank cells Not reported, not applicable or unavailable Populated · full table 1,992,002 / 1,992,002 (100.00%)
Sample point name `sample_point_name`	Name of the reported sample point. Type text Blank cells Not reported, not applicable or unavailable Populated · full table 1,992,002 / 1,992,002 (100.00%)
Sample point type `sample_point_type`	Type of sample point, such as entry point to the distribution system. Type text Blank cells Not reported, not applicable or unavailable Populated · full table 1,992,002 / 1,992,002 (100.00%)
Associated facility ID `associated_facility_id`	Related facility identifier supplied in the UCMR record. Type text Blank cells Not reported, not applicable or unavailable Populated · full table 0 / 1,992,002 (0.00%)
Associated sample point ID `associated_sample_point_id`	Related sample-point identifier supplied in the UCMR record. Type text Blank cells Not reported, not applicable or unavailable Populated · full table 0 / 1,992,002 (0.00%)
Collection date `collection_date`	Date the UCMR sample was collected. Type text Blank cells Not reported, not applicable or unavailable Populated · full table 1,992,002 / 1,992,002 (100.00%)
Sample ID `sample_id`	Sample identifier assigned in the UCMR record. Type text Blank cells Not reported, not applicable or unavailable Populated · full table 1,992,002 / 1,992,002 (100.00%)
Contaminant `contaminant`	Name of the contaminant tested. Type text Blank cells Not reported, not applicable or unavailable Populated · full table 1,992,002 / 1,992,002 (100.00%)
MRL `mrl`	Minimum reporting level in the separately reported Units; not a health standard. Type text Unit As stated in units Blank cells Not reported, not applicable or unavailable Populated · full table 1,992,002 / 1,992,002 (100.00%)
Units `units`	Unit of the analytical result and minimum reporting level (MRL). Type text Blank cells Not reported, not applicable or unavailable Populated · full table 1,992,002 / 1,992,002 (100.00%)
Method ID `method_id`	Analytical method identifier used for the test. Type text Blank cells Not reported, not applicable or unavailable Populated · full table 1,992,002 / 1,992,002 (100.00%)
Analytical results sign `analytical_results_sign`	Reported qualifier. < means below the reporting level; never replace the blank measurement with zero. Type text Blank cells Not reported, not applicable or unavailable Populated · full table 1,992,002 / 1,992,002 (100.00%)
Analytical result value `analytical_result_value`	Reported concentration. A blank below-reporting-level result is censored, not a measured zero. Type text Unit As stated in units Blank cells Not reported, not applicable or unavailable Populated · full table 57,501 / 1,992,002 (2.89%)
Sample event code `sample_event_code`	UCMR sampling event identifier; links additional data elements to the sample event. Type text Blank cells Not reported, not applicable or unavailable Populated · full table 1,992,002 / 1,992,002 (100.00%)
Monitoring requirement `monitoring_requirement`	Monitoring requirement category recorded for the UCMR observation. Type text Blank cells Not reported, not applicable or unavailable Populated · full table 1,992,002 / 1,992,002 (100.00%)
Region `region`	EPA region of the public water system. Type text Blank cells Not reported, not applicable or unavailable Populated · full table 1,992,002 / 1,992,002 (100.00%)
State `state`	State of the public water system. Type text Blank cells Not reported, not applicable or unavailable Populated · full table 1,992,002 / 1,992,002 (100.00%)
Legacy UCMR sample type `ucmr1sample_type`	Legacy sample-type field retained in the published UCMR layout. Type text Blank cells Not reported, not applicable or unavailable Populated · full table 0 / 1,992,002 (0.00%)

facilities.csv20 fields

Field	Definition & format
Source row number `source_row_number`	One-based data-row ordinal in the exact source member. Type integer Format Derived count or ordinal Blank cells Not reported, not applicable or unavailable Populated · full table 1,554,832 / 1,554,832 (100.00%)
Submission fiscal year and quarter `submissionyearquarter`	SDWIS federal fiscal-year/quarter submission label; not the date of the underlying event. Type text Blank cells Not reported, not applicable or unavailable Populated · full table 1,554,832 / 1,554,832 (100.00%)
PWSID `pwsid`	Public water system identifier; combines with facility and sample identifiers to link related records. Type text Blank cells Not reported, not applicable or unavailable Populated · full table 1,554,832 / 1,554,832 (100.00%)
Facility ID `facility_id`	Facility ID that, when used with the PWSID, uniquely identifies a water system facility. Type text Blank cells Not reported, not applicable or unavailable Populated · full table 1,554,832 / 1,554,832 (100.00%)
Facility name `facility_name`	The name of the water system facility. Type text Blank cells Not reported, not applicable or unavailable Populated · full table 1,525,556 / 1,554,832 (98.12%)
State facility ID `state_facility_id`	Facility identifier used by the state’s own data system. Type text Blank cells Not reported, not applicable or unavailable Populated · full table 1,080,934 / 1,554,832 (69.52%)
Facility activity code `facility_activity_code`	Reported facility activity code. Decode using reference_codes.csv with VALUE_TYPE=ACTIVITY_CODE; preserve the reporting quarter. Type text Blank cells Not reported, not applicable or unavailable Populated · full table 1,554,832 / 1,554,832 (100.00%)
Facility deactivation date `facility_deactivation_date`	The date the facility was deactivated (no longer actively serving water) or removed from federal oversight because it no longer met SDWA criteria as a public water system. Type text Blank cells Not reported, not applicable or unavailable Populated · full table 570,319 / 1,554,832 (36.68%)
Facility type code `facility_type_code`	Code identifying the type of facility. Type text Blank cells Not reported, not applicable or unavailable Populated · full table 1,554,832 / 1,554,832 (100.00%)
Submission status code `submission_status_code`	Code that indicates whether an active water system was reported, rejected, or not reported during the recent inventory submission. This field is not applicable to inactive water systems. Generated by ODS. Type text Blank cells Not reported, not applicable or unavailable Populated · full table 1,554,832 / 1,554,832 (100.00%)
Is source ind `is_source_ind`	Whether the facility is a source, such as a well, intake, spring, reservoir or purchased-water connection. Type text Blank cells Not reported, not applicable or unavailable Populated · full table 1,554,832 / 1,554,832 (100.00%)
Water type code `water_type_code`	Character code identifying the type of water source. Ground water (GW), Surface water (SW), Ground water under the influence of surface water (GU). Type text Blank cells Not reported, not applicable or unavailable Populated · full table 713,768 / 1,554,832 (45.91%)
Availability code `availability_code`	A single-character code for how the water source is utilized by a water system. Type text Blank cells Not reported, not applicable or unavailable Populated · full table 739,141 / 1,554,832 (47.54%)
Seller treatment code `seller_treatment_code`	Code that indicates the treatment status of the water. Applies only to source facilities. Type text Blank cells Not reported, not applicable or unavailable Populated · full table 51,264 / 1,554,832 (3.30%)
Seller PWSID `seller_pwsid`	Reported seller water-system identifier. This edge does not prove continuous physical supply. Type text Blank cells Not reported, not applicable or unavailable Populated · full table 49,222 / 1,554,832 (3.17%)
Seller PWS name `seller_pws_name`	Name of the upstream system reported as supplying water through this connection. Type text Blank cells Not reported, not applicable or unavailable Populated · full table 49,169 / 1,554,832 (3.16%)
Filtration status code `filtration_status_code`	State-reported filtration requirement or filtration-avoidance status for applicable surface-water sources. Type text Blank cells Not reported, not applicable or unavailable Populated · full table 31,002 / 1,554,832 (1.99%)
Is source treated ind `is_source_treated_ind`	Indicates whether the water system source water is being treated or not. Type text Blank cells Not reported, not applicable or unavailable Populated · full table 527,441 / 1,554,832 (33.92%)
First reported date `first_reported_date`	First date this record was reported to SDWIS. Type text Blank cells Not reported, not applicable or unavailable Populated · full table 704,646 / 1,554,832 (45.32%)
Last reported date `last_reported_date`	Most recent date this record was reported to SDWIS. Type text Blank cells Not reported, not applicable or unavailable Populated · full table 1,543,399 / 1,554,832 (99.26%)

supply_relationships.csv11 fields

Field	Definition & format
Source row number `source_row_number`	One-based data-row ordinal in the exact source member. Type integer Format Derived count or ordinal Blank cells Not reported, not applicable or unavailable Populated · full table 49,222 / 49,222 (100.00%)
Submission fiscal year and quarter `submissionyearquarter`	SDWIS federal fiscal-year/quarter submission label; not the date of the underlying event. Type text Blank cells Not reported, not applicable or unavailable Populated · full table 49,222 / 49,222 (100.00%)
PWSID `pwsid`	Public water system identifier; combines with facility and sample identifiers to link related records. Type text Blank cells Not reported, not applicable or unavailable Populated · full table 49,222 / 49,222 (100.00%)
Facility ID `facility_id`	Facility ID that, when used with the PWSID, uniquely identifies a water system facility. Type text Blank cells Not reported, not applicable or unavailable Populated · full table 49,222 / 49,222 (100.00%)
Facility name `facility_name`	The name of the water system facility. Type text Blank cells Not reported, not applicable or unavailable Populated · full table 48,207 / 49,222 (97.94%)
Facility activity code `facility_activity_code`	Reported facility activity code. Decode using reference_codes.csv with VALUE_TYPE=ACTIVITY_CODE; preserve the reporting quarter. Type text Blank cells Not reported, not applicable or unavailable Populated · full table 49,222 / 49,222 (100.00%)
Seller PWSID `seller_pwsid`	Reported seller water-system identifier. This edge does not prove continuous physical supply. Type text Blank cells Not reported, not applicable or unavailable Populated · full table 49,222 / 49,222 (100.00%)
Seller PWS name `seller_pws_name`	Name of the upstream system reported as supplying water through this connection. Type text Blank cells Not reported, not applicable or unavailable Populated · full table 49,169 / 49,222 (99.89%)
Seller treatment code `seller_treatment_code`	Code that indicates the treatment status of the water. Applies only to source facilities. Type text Blank cells Not reported, not applicable or unavailable Populated · full table 49,216 / 49,222 (99.99%)
Availability code `availability_code`	A single-character code for how the water source is utilized by a water system. Type text Blank cells Not reported, not applicable or unavailable Populated · full table 48,371 / 49,222 (98.27%)
Last reported date `last_reported_date`	Most recent date this record was reported to SDWIS. Type text Blank cells Not reported, not applicable or unavailable Populated · full table 48,759 / 49,222 (99.06%)

geographic_areas.csv12 fields

Field	Definition & format
Source row number `source_row_number`	One-based data-row ordinal in the exact source member. Type integer Format Derived count or ordinal Blank cells Not reported, not applicable or unavailable Populated · full table 578,198 / 578,198 (100.00%)
Submission fiscal year and quarter `submissionyearquarter`	SDWIS federal fiscal-year/quarter submission label; not the date of the underlying event. Type text Blank cells Not reported, not applicable or unavailable Populated · full table 578,198 / 578,198 (100.00%)
PWSID `pwsid`	Public water system identifier; combines with facility and sample identifiers to link related records. Type text Blank cells Not reported, not applicable or unavailable Populated · full table 578,198 / 578,198 (100.00%)
Geo ID `geo_id`	Source identifier for the water-system/geographic-area record. Type text Blank cells Not reported, not applicable or unavailable Populated · full table 578,198 / 578,198 (100.00%)
Area type code `area_type_code`	Code identifying the area type where the facility is located. Type text Blank cells Not reported, not applicable or unavailable Populated · full table 578,198 / 578,198 (100.00%)
Tribal code `tribal_code`	EPA code which represents the Indian reservation or Alaska Remote Village being served by a Water System. A full discription of the codes can be accessed in the SDWA_REF_CODE_VALUES.csv. Type text Blank cells Not reported, not applicable or unavailable Populated · full table 1,386 / 578,198 (0.24%)
State served `state_served`	The state that the facility is serving. Type text Blank cells Not reported, not applicable or unavailable Populated · full table 158,006 / 578,198 (27.33%)
ANSI entity code `ansi_entity_code`	ANSI geographic identifier for the county, city or statistical area; interpret with its state. Type text Blank cells Not reported, not applicable or unavailable Populated · full table 411,651 / 578,198 (71.20%)
ZIP code served `zip_code_served`	The 5-digit postal zip code that the facility serves. Type text Blank cells Not reported, not applicable or unavailable Populated · full table 7,155 / 578,198 (1.24%)
City served `city_served`	The name of the city that the facility serves. Type text Blank cells Not reported, not applicable or unavailable Populated · full table 158,006 / 578,198 (27.33%)
County served `county_served`	The name of the county that the facility serves. Type text Blank cells Not reported, not applicable or unavailable Populated · full table 405,396 / 578,198 (70.11%)
Last reported date `last_reported_date`	Most recent date this record was reported to SDWIS. Type text Blank cells Not reported, not applicable or unavailable Populated · full table 578,198 / 578,198 (100.00%)

service_areas.csv7 fields

Field	Definition & format
Source row number `source_row_number`	One-based data-row ordinal in the exact source member. Type integer Format Derived count or ordinal Blank cells Not reported, not applicable or unavailable Populated · full table 422,464 / 422,464 (100.00%)
Submission fiscal year and quarter `submissionyearquarter`	SDWIS federal fiscal-year/quarter submission label; not the date of the underlying event. Type text Blank cells Not reported, not applicable or unavailable Populated · full table 422,464 / 422,464 (100.00%)
PWSID `pwsid`	Public water system identifier; combines with facility and sample identifiers to link related records. Type text Blank cells Not reported, not applicable or unavailable Populated · full table 422,464 / 422,464 (100.00%)
Service area type code `service_area_type_code`	Service-area classification; decode in reference_codes.csv under SERVICE_AREA_CODE. Type text Blank cells Not reported, not applicable or unavailable Populated · full table 422,464 / 422,464 (100.00%)
Is primary service area code `is_primary_service_area_code`	Indicates whether the area is the primary service area served by the water system. Type text Blank cells Not reported, not applicable or unavailable Populated · full table 322,994 / 422,464 (76.45%)
First reported date `first_reported_date`	First date this record was reported to SDWIS. Type text Blank cells Not reported, not applicable or unavailable Populated · full table 89,554 / 422,464 (21.20%)
Last reported date `last_reported_date`	Most recent date this record was reported to SDWIS. Type text Blank cells Not reported, not applicable or unavailable Populated · full table 421,176 / 422,464 (99.70%)

lead_copper_results.csv16 fields

Field	Definition & format
Source row number `source_row_number`	One-based data-row ordinal in the exact source member. Type integer Format Derived count or ordinal Blank cells Not reported, not applicable or unavailable Populated · full table 927,415 / 927,415 (100.00%)
Submission fiscal year and quarter `submissionyearquarter`	SDWIS federal fiscal-year/quarter submission label; not the date of the underlying event. Type text Blank cells Not reported, not applicable or unavailable Populated · full table 927,415 / 927,415 (100.00%)
PWSID `pwsid`	Public water system identifier; combines with facility and sample identifiers to link related records. Type text Blank cells Not reported, not applicable or unavailable Populated · full table 927,415 / 927,415 (100.00%)
Sample ID `sample_id`	Identifier used to identify the sample. Type text Blank cells Not reported, not applicable or unavailable Populated · full table 927,415 / 927,415 (100.00%)
Sampling end date `sampling_end_date`	Date of the last day of the monitoring period in which 90th percentile data for lead or copper was acquired. Type text Blank cells Not reported, not applicable or unavailable Populated · full table 927,415 / 927,415 (100.00%)
Sampling start date `sampling_start_date`	Date of the first day of the monitoring period in which 90th percentile data for lead or copper was acquired. Type text Blank cells Not reported, not applicable or unavailable Populated · full table 927,415 / 927,415 (100.00%)
Reconciliation ID `reconciliation_id`	An identifier used for reconciliation with the state data system or LAB assigned identifiers. Type text Blank cells Not reported, not applicable or unavailable Populated · full table 621 / 927,415 (0.07%)
Sample first reported date `sample_first_reported_date`	Date that the sample was first reported. The date format is MM/DD/YYYY. Type text Blank cells Not reported, not applicable or unavailable Populated · full table 924,785 / 927,415 (99.72%)
Sample last reported date `sample_last_reported_date`	Most recent date the sample was reported. Type text Blank cells Not reported, not applicable or unavailable Populated · full table 874,711 / 927,415 (94.32%)
Sample analytical result ID `sar_id`	Reporting-jurisdiction identifier for an analytical result; distinguishes multiple results for one sample. Type text Blank cells Not reported, not applicable or unavailable Populated · full table 927,415 / 927,415 (100.00%)
Contaminant code `contaminant_code`	EPA contaminant identifier; code descriptions are in reference_codes.csv. Type text Blank cells Not reported, not applicable or unavailable Populated · full table 927,415 / 927,415 (100.00%)
Result sign code `result_sign_code`	Indicates if the sample result was below the minimum detection limit or equal to the value reported. Type text Blank cells Not reported, not applicable or unavailable Populated · full table 7,780 / 927,415 (0.84%)
Sample measure `sample_measure`	Reported Lead and Copper Rule result or percentile value; preserve RESULT_SIGN_CODE and UNIT_OF_MEASURE. Type text Unit As stated in unit_of_measure Blank cells Not reported, not applicable or unavailable Populated · full table 927,415 / 927,415 (100.00%)
Unit of measure `unit_of_measure`	Unit code for the reported analytical measurement and applicable contaminant limit in this table. Type text Blank cells Not reported, not applicable or unavailable Populated · full table 927,415 / 927,415 (100.00%)
Sar first reported date `sar_first_reported_date`	The date of the first reported sample analytical result. Type text Blank cells Not reported, not applicable or unavailable Populated · full table 692,189 / 927,415 (74.64%)
Sar last reported date `sar_last_reported_date`	The most recent reported sample analytical result. Type text Blank cells Not reported, not applicable or unavailable Populated · full table 643,344 / 927,415 (69.37%)

violation_enforcement.csv39 fields

Field	Definition & format
Source row number `source_row_number`	One-based data-row ordinal in the exact source member. Type integer Format Derived count or ordinal Blank cells Not reported, not applicable or unavailable Populated · full table 2,254,413 / 2,254,413 (100.00%)
Submission fiscal year and quarter `submissionyearquarter`	SDWIS federal fiscal-year/quarter submission label; not the date of the underlying event. Type text Blank cells Not reported, not applicable or unavailable Populated · full table 2,254,413 / 2,254,413 (100.00%)
PWSID `pwsid`	Public water system identifier; combines with facility and sample identifiers to link related records. Type text Blank cells Not reported, not applicable or unavailable Populated · full table 2,254,413 / 2,254,413 (100.00%)
Violation ID `violation_id`	Reported violation identifier. Enforcement rows can repeat a violation; count distinct IDs when measuring violations. Type text Blank cells Not reported, not applicable or unavailable Populated · full table 2,254,413 / 2,254,413 (100.00%)
Facility ID `facility_id`	Facility ID that, when used with the PWSID, uniquely identifies a water system facility. Type text Blank cells Not reported, not applicable or unavailable Populated · full table 1,281,930 / 2,254,413 (56.86%)
Compliance period start `compl_per_begin_date`	Beginning of the compliance period associated with the violation. Type text Blank cells Not reported, not applicable or unavailable Populated · full table 2,254,413 / 2,254,413 (100.00%)
Compliance period end `compl_per_end_date`	End of the compliance period associated with the violation. Type text Blank cells Not reported, not applicable or unavailable Populated · full table 1,793,957 / 2,254,413 (79.58%)
Noncompliance period start `non_compl_per_begin_date`	Beginning of the noncompliance period during which a violation was identified. Type text Blank cells Not reported, not applicable or unavailable Populated · full table 2,254,413 / 2,254,413 (100.00%)
Noncompliance period end `non_compl_per_end_date`	End of the violation’s noncompliance period; can remain blank while unresolved or use a later resolving action under EPA’s rules. Type text Blank cells Not reported, not applicable or unavailable Populated · full table 2,254,413 / 2,254,413 (100.00%)
PWS deactivation date `pws_deactivation_date`	The date in which the water system was reported as being closed/deactivated. Type text Blank cells Not reported, not applicable or unavailable Populated · full table 197,823 / 2,254,413 (8.77%)
Violation code `violation_code`	Violation code; decode with reference_codes.csv using the matching value_type. Type text Blank cells Not reported, not applicable or unavailable Populated · full table 2,254,413 / 2,254,413 (100.00%)
Violation category code `violation_category_code`	The category of violation that is reported. Type text Blank cells Not reported, not applicable or unavailable Populated · full table 2,254,413 / 2,254,413 (100.00%)
Is health based ind `is_health_based_ind`	Indicates if this is a health based violation. Valid values are Y (yes) or N (no). Type text Blank cells Not reported, not applicable or unavailable Populated · full table 2,254,413 / 2,254,413 (100.00%)
Contaminant code `contaminant_code`	EPA contaminant identifier; code descriptions are in reference_codes.csv. Type text Blank cells Not reported, not applicable or unavailable Populated · full table 2,254,368 / 2,254,413 (100.00%)
Viol measure `viol_measure`	Analytical result associated with a contaminant-level violation; read with unit_of_measure. Type text Unit As stated in unit_of_measure Blank cells Not reported, not applicable or unavailable Populated · full table 142,041 / 2,254,413 (6.30%)
Unit of measure `unit_of_measure`	Unit code for the reported analytical measurement and applicable contaminant limit in this table. Type text Blank cells Not reported, not applicable or unavailable Populated · full table 142,041 / 2,254,413 (6.30%)
Federal MCL `federal_mcl`	Federal maximum contaminant level associated with the violation; read with unit_of_measure. Type text Unit As stated in unit_of_measure Blank cells Not reported, not applicable or unavailable Populated · full table 1,325,888 / 2,254,413 (58.81%)
State MCL `state_mcl`	State maximum contaminant level associated with the violation; read with unit_of_measure. Type text Unit As stated in unit_of_measure Blank cells Not reported, not applicable or unavailable Populated · full table 124,301 / 2,254,413 (5.51%)
Is major viol ind `is_major_viol_ind`	A code value that indicates whether a Monitoring and Reporting (MR) violation is major or minor. The major versus minor designation does not apply to a sanitary survey MR violation. Type text Blank cells Not reported, not applicable or unavailable Populated · full table 1,637,533 / 2,254,413 (72.64%)
Violation severity count `severity_ind_cnt`	A count indicating the severity of certain DBPR and IESWTR violations. Type text Blank cells Not reported, not applicable or unavailable Populated · full table 54,078 / 2,254,413 (2.40%)
Calculated return-to-compliance date `calculated_rtc_date`	The date the system returned to compliance. Type text Blank cells Not reported, not applicable or unavailable Populated · full table 2,177,286 / 2,254,413 (96.58%)
Violation status `violation_status`	Source status: Resolved, Archived, Addressed or Unaddressed. Archived can reflect age or system inactivity and does not mean resolved. Type text Blank cells Not reported, not applicable or unavailable Populated · full table 2,254,413 / 2,254,413 (100.00%)
Public notification tier `public_notification_tier`	Reported public-notification tier associated with the violation. Type text Blank cells Not reported, not applicable or unavailable Populated · full table 2,254,413 / 2,254,413 (100.00%)
Calculated pub notif tier `calculated_pub_notif_tier`	Public-notification tier calculated by the source system. Type text Blank cells Not reported, not applicable or unavailable Populated · full table 2,254,413 / 2,254,413 (100.00%)
Viol originator code `viol_originator_code`	Code that indicates who the violation was initiated by. Type text Blank cells Not reported, not applicable or unavailable Populated · full table 2,254,413 / 2,254,413 (100.00%)
Sample result ID `sample_result_id`	A system-generated number managed by the reporting jurisdiction that uniquely identifies each sample result record. Type text Blank cells Not reported, not applicable or unavailable Populated · full table 43,238 / 2,254,413 (1.92%)
Corrective action ID `corrective_action_id`	Corrective action identifier. Type text Blank cells Not reported, not applicable or unavailable Populated · full table 27,852 / 2,254,413 (1.24%)
Rule code `rule_code`	Code for a National Drinking Water rule. Type text Blank cells Not reported, not applicable or unavailable Populated · full table 2,254,413 / 2,254,413 (100.00%)
Rule group code `rule_group_code`	Code that uniquely identifies a rule group. Type text Blank cells Not reported, not applicable or unavailable Populated · full table 2,254,413 / 2,254,413 (100.00%)
Rule family code `rule_family_code`	Code for rule family. Type text Blank cells Not reported, not applicable or unavailable Populated · full table 2,254,413 / 2,254,413 (100.00%)
Viol first reported date `viol_first_reported_date`	Date of the first reported violation. Type text Blank cells Not reported, not applicable or unavailable Populated · full table 2,254,413 / 2,254,413 (100.00%)
Viol last reported date `viol_last_reported_date`	Date of the last reported violation. Type text Blank cells Not reported, not applicable or unavailable Populated · full table 2,196,260 / 2,254,413 (97.42%)
Enforcement ID `enforcement_id`	Reported enforcement action identifier; multiple actions can accompany one violation. Type text Blank cells Not reported, not applicable or unavailable Populated · full table 2,198,377 / 2,254,413 (97.51%)
Enforcement date `enforcement_date`	Date of the reported enforcement action. Type text Blank cells Not reported, not applicable or unavailable Populated · full table 2,198,377 / 2,254,413 (97.51%)
Enforcement action type code `enforcement_action_type_code`	Code for the enforcement follow-up action; decode under ENFORCEMENT_ACTION_TYPE_CODE in reference_codes.csv. Type text Blank cells Not reported, not applicable or unavailable Populated · full table 2,198,377 / 2,254,413 (97.51%)
Enf action category `enf_action_category`	Category of the enforcement action against the violation. Type text Blank cells Not reported, not applicable or unavailable Populated · full table 2,198,369 / 2,254,413 (97.51%)
Enf originator code `enf_originator_code`	Code that indicates who the enforcement action was initiated by. Type text Blank cells Not reported, not applicable or unavailable Populated · full table 2,198,377 / 2,254,413 (97.51%)
Enf first reported date `enf_first_reported_date`	Date of the first reported enforcement action against the violation. Type text Blank cells Not reported, not applicable or unavailable Populated · full table 2,198,377 / 2,254,413 (97.51%)
Enf last reported date `enf_last_reported_date`	Date of the last reported enforcement action against the violation. Type text Blank cells Not reported, not applicable or unavailable Populated · full table 2,073,013 / 2,254,413 (91.95%)

reference_codes.csv4 fields

Field	Definition & format
Source row number `source_row_number`	One-based data-row ordinal in the exact source member. Type integer Format Derived count or ordinal Blank cells Not reported, not applicable or unavailable Populated · full table 2,376 / 2,376 (100.00%)
Value type `value_type`	Source code namespace. Match this and value_code together; the same code can occur in different namespaces. System/facility activity fields use ACTIVITY_CODE. Type text Blank cells Not reported, not applicable or unavailable Populated · full table 2,376 / 2,376 (100.00%)
Value code `value_code`	Literal source code, including leading zeros. Decode only within its value_type namespace. Type text Blank cells Not reported, not applicable or unavailable Populated · full table 2,376 / 2,376 (100.00%)
Value description `value_description`	The full description of the code in VALUE_CODE. Type text Blank cells Not reported, not applicable or unavailable Populated · full table 2,376 / 2,376 (100.00%)

ucmr_additional_elements.csv7 fields

Field	Definition & format
Source row number `source_row_number`	One-based data-row ordinal in the exact source member. Type integer Format Derived count or ordinal Blank cells Not reported, not applicable or unavailable Populated · full table 436,993 / 436,993 (100.00%)
PWSID `pwsid`	Public water system identifier; combines with facility and sample identifiers to link related records. Type text Blank cells Not reported, not applicable or unavailable Populated · full table 436,993 / 436,993 (100.00%)
Facility ID `facility_id`	Facility identifier within the public water system; not nationally unique on its own. Type text Blank cells Not reported, not applicable or unavailable Populated · full table 436,993 / 436,993 (100.00%)
Sample point ID `sample_point_id`	Sample-point identifier within the water-system facility. Type text Blank cells Not reported, not applicable or unavailable Populated · full table 436,993 / 436,993 (100.00%)
Sample event code `sample_event_code`	UCMR sampling event identifier; links additional data elements to the sample event. Type text Blank cells Not reported, not applicable or unavailable Populated · full table 436,993 / 436,993 (100.00%)
Additional data element `additional_data_element`	Name of an additional UCMR data element collected for the sample event. Type text Blank cells Not reported, not applicable or unavailable Populated · full table 436,993 / 436,993 (100.00%)
Response `response`	Reported response to additional_data_element; retain its source meaning and missingness. Type text Blank cells Not reported, not applicable or unavailable Populated · full table 436,993 / 436,993 (100.00%)

ucmr_zip_areas.csv3 fields

Field	Definition & format
Source row number `source_row_number`	One-based data-row ordinal in the exact source member. Type integer Format Derived count or ordinal Blank cells Not reported, not applicable or unavailable Populated · full table 31,429 / 31,429 (100.00%)
PWSID `pwsid`	Public water system identifier; combines with facility and sample identifiers to link related records. Type text Blank cells Not reported, not applicable or unavailable Populated · full table 31,429 / 31,429 (100.00%)
ZIP code `zipcode`	ZIP code served by the public water system, from the UCMR ZIP-area file. Type text Blank cells Not reported, not applicable or unavailable Populated · full table 31,429 / 31,429 (100.00%)

Field coverage

Download field coverage (CSV)

Data notes

Coverage counts use the full tables. They exclude blank cells and empty JSON collections; zero and false count as populated.

The primary count includes inactive and other reported activity codes. Capture date, reporting quarter and monitoring date describe different events.
A missing observation does not establish clean water; a nondetect is not zero. UCMR5 monitoring is not a compliance determination or household exposure estimate.
Several enforcement actions can repeat the same violation. Some UCMR observations reference systems absent from the captured inventory.
Seller relationships can describe emergency or seasonal availability and do not establish actual water flow.
Administrative person names, email addresses and freeform additional-element text are withheld. Decode source codes using value_type and value_code together.