Public water system · TX1011744
ActiveNorthwest Harris County MUD 21
At a glance
Northwest Harris County MUD 21 (PWSID TX1011744) is an active community water system in Harris County, Texas. It reports serving 2,493 people through 1,377 service connections. Its primary water source is purchased surface water, and EPA lists it as owned by a local government. EPA's records list one violation for this system; it is not health-based, and the most recent began in October 2011.
Dataset updated . Source: EPA SDWIS/ECHO public records.
Population served
2,493
Service connections
1,377
Primary source
SWP
Purchased surface water
System type
CWS
Community water system
System record
How does Northwest Harris County MUD 21 compare with other water systems in Harris County?
By EPA's size categories, Northwest Harris County MUD 21 is a small system (501 to 3,300 people). Harris County has 1,246 active public water systems. Its population served is about half of the county average of 4,849 people per system, and accounts for less than 0.1% of the 6,041,784 people reported by systems filed under the county. Across Texas, the 7,078 active systems average 4,789 people each. Nationally, the average active community water system reports serving 6,703 people, so Northwest Harris County MUD 21 is about 63% below that figure.
What does “community water system” mean?
A community water system serves at least 15 connections used by year-round residents, or regularly serves at least 25 year-round residents. Homes, apartments and mobile-home parks are served by these. Texas has 4,594 active community water systems, 65% of the state's 7,078 active systems. Purchased surface water means the system buys surface water from another public water system rather than drawing its own. 1,192 Texas systems (17%) list purchased surface water as their primary source.
Who owns and regulates Northwest Harris County MUD 21?
EPA lists Northwest Harris County MUD 21 as owned by a local government. The TX state drinking water program is its primacy agency, the regulator with primary enforcement responsibility for the system under the Safe Drinking Water Act. 508 of the 1,246 active systems in Harris County (41%) are also owned by a local government.
Does Northwest Harris County MUD 21 have drinking water violations?
EPA's records list one violation for this system; it is not health-based, and the most recent began in October 2011. By type: 1 monitoring and reporting. The contaminant or rule involved is Lead and Copper Rule. EPA lists 1 as resolved. Resolved means at least one resolving action is on record: the system returned to compliance, the rule no longer applies, or no further action was needed.
| Began | Violation | Contaminant or rule | Health-based | Status |
|---|---|---|---|---|
| 2011-10-01 | Monitoring and reportingFollow-up Or Routine LCR Tap M/R · code 52 | Lead and Copper Rulecode 5000 | No | Resolved |
The one violation in EPA's records.Labels and codes come from EPA's SDWIS reference tables. A monitoring or reporting violation means a required test or report was missed or late; it does not by itself mean a contaminant was found. "Health-based" marks violations of a legal limit or required treatment.
Northwest Harris County MUD 21: frequently asked questions
Who runs Northwest Harris County MUD 21?
Northwest Harris County MUD 21 (PWSID TX1011744) is a community water system owned by a local government. It is regulated by the TX state drinking water program.
How many people does Northwest Harris County MUD 21 serve?
Northwest Harris County MUD 21 reports serving 2,493 people through 1,377 service connections in Harris County, Texas.
Where does Northwest Harris County MUD 21 get its water?
EPA SDWIS lists this system's primary water source as purchased surface water. Purchased surface water means the system buys surface water from another public water system rather than drawing its own.
Does Northwest Harris County MUD 21 have any drinking water violations?
EPA's records list one violation for this system; it is not health-based, and the most recent began in October 2011. A monitoring or reporting violation means a required test or report was missed or late; it does not by itself mean a contaminant was found.
Is Northwest Harris County MUD 21's water safe to drink?
AquaCensus shows EPA compliance records, not current water test results, so it cannot say whether the water is safe at a given moment. EPA's records list one violation for this system; it is not health-based, and the most recent began in October 2011. For current results, consult the system's annual water quality report, EPA ECHO, or the TX state drinking water program.
Where can I find Northwest Harris County MUD 21's water quality report?
As a community water system, Northwest Harris County MUD 21 must deliver an annual water quality report, called a Consumer Confidence Report, to its customers by July 1 each year, covering the previous calendar year. The system can provide a copy on request.
Other water systems in Harris County
| Water system | County | Population served | Type | Source |
|---|---|---|---|---|
| City of Houston | Harris | 2,970,543 | Community | Surface water |
| City of Pasadena | Harris | 152,000 | Community | Purchased surface water |
| Clear Lake City Water Authority | Harris | 89,702 | Community | Purchased surface water |
| City of Baytown | Harris | 86,004 | Community | Purchased surface water |
| City of Houston Ud 5 - Kingwood | Harris | 80,073 | Community | Groundwater |
| Harris County MUD 165 | Harris | 40,503 | Community | Purchased surface water |
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About this data
Source: U.S. EPA Safe Drinking Water Information System (SDWIS) and SDWA violation records, via EPA ECHO, as published October 1, 2026 — AquaCensus refreshes it quarterly. See the methodology for how records are matched, cleaned and scored.
Cite as: AquaCensus, “Northwest Harris County MUD 21, PWSID TX1011744, Texas”, https://aquacensus.com/water-systems/texas/northwest-harris-county-mud-21-tx1011744 (data as of October 1, 2026).