Is Western MWD water safe to drink?

Western MWD (PWS ID: CA3310049) has 0 recorded violations in the EPA SDWIS database. PFAS contamination has been detected in UCMR5 testing, with 3 PFAS compounds found. EPA SDWIS lists this system's service population as 86,062 people using Surface Water sources.

How many people does Western MWD serve?

EPA SDWIS reports that Western MWD serves 86,062 people (this public water system's service population, not the municipal population of Riverside or any other city). It is a Local-owned system using Surface Water water sources with 22,297 service connections. The operator address is listed in Riverside, California.

What type of violations does Western MWD have?

Western MWD has 0 total violations: 0 health-based violations (MCL exceedances or treatment failures), 0 monitoring/reporting violations, and 0 treatment technique violations. Health-based violations indicate contaminant levels exceeded EPA safe limits.

Has PFAS been detected in Western MWD water?

Yes. UCMR5 testing detected 3 PFAS compounds in Western MWD's water supply: PFHxS, PFBS, PFPeA. PFAS are persistent "forever chemicals" that do not break down in the environment.

What water source does Western MWD use?

Western MWD uses Surface Water as its primary water source. It is classified as a Community Water System (CWS), serving residential populations year-round.

Where does this data come from?

All data comes from the EPA Safe Drinking Water Information System (SDWIS) and the UCMR5 PFAS monitoring program. SDWIS tracks compliance for all public water systems regulated under the Safe Drinking Water Act.

Where does Western MWD sit among U.S. public water systems?

According to EPA SDWIS population_served among sitemap-advertised systems (serving 500+), Western MWD ranks #591 of 29,740 by people served, and #111 of 1,701 in California. Ordinals use population_served DESC among systems serving 500+ (the sitemap cohort). See /methodology#corpus-placement.

How does Western MWD's violation count compare nationally?

Western MWD has 0 recorded EPA SDWIS violations, fewer than 96% of the 29,740 public water systems serving 500 or more people nationwide (the same sitemap cohort used for the corpus-placement ranking above). 0% of that cohort has fewer violations than Western MWD. A system can have zero recorded violations and still be actively monitored, and a high violation count often reflects a system that reports thoroughly, not necessarily one with worse water.

States → California

Community Water System · PWS CA3310049

Western MWD

Operator location Riverside, California - larger served population (> 3,309) at 86,062 people served; 0 SDWIS violations on record from surface water sources.

Compiled by PlainWater · May 15, 2026

86,062
People served (this PWS) Larger third of systems: 0
EPA violations (this PWS) Lower third of systems: 0
Health-based (this PWS) No violations on record: 3 PFAS
UCMR5 (this PWS) Middle third of PFAS-detected systems

Follow published updates (RSS)

Western MWD standing, low SDWIS violation third

86,062 people served (SDWIS) - larger served population (> 3,309). Corpus terciles use 29,740 systems serving 500+ (the sitemap cohort). UCMR5: middle-third PFAS panel (≤ 4 compounds). Population rank #591 of 29,740 among systems serving 500+.

The verdict

Western MWD is in the lower third by violation count (0; lower-third violation load (≤ 21 violations)). A low count does not mean the system is unmonitored - monitoring and reporting violations still appear in SDWIS. Population served is large (86,062; larger served population (> 3,309)), so household exposure scale sits behind the violation mix. No violations are on record in this extract. UCMR5 detected 3 PFAS compounds (middle-third PFAS panel (≤ 4 compounds)).

#591 of 29,740
Population · /systems: #111 of 1,701
Population · CA: 0
Total EPA violations on record: 0%
Health-based (MCL / treatment failure)

Population ordinals match the sitemap cohort (systems serving 500+, population_served DESC). See methodology · corpus placement.

PFAS Detected

3 PFAS "forever chemicals" detected in testing under EPA's UCMR5 monitoring program.

Water Safety Score

89/100

Western MWD

Based on EPA SDWIS violation history and UCMR5 PFAS testing only, not water taste, odor, infrastructure age, or contaminants outside the federally tracked set.

Health-based violations A+

EPA SDWIS health-based violations on record (MCL, MRDL, treatment technique)

Monitoring & reporting violations A+

Non-health SDWIS violations (monitoring, reporting, and other compliance)

PFAS contamination A

0.0047 µg/L

Highest PFAS compound level detected in UCMR5 testing

System Details

System Type: Community
Owner Type: Local
Connections: 22,297
County: Riverside
School/Daycare: No
MCL Violations: 0
Monitoring Violations: 0
Treatment Tech Violations: 0

Violation Count vs. the National Corpus

Western MWD has 0 recorded EPA violations, 0% of the 29,740 public water systems serving 500+ people nationwide carry fewer, and 96% carry more. 0% of this system's own violations are health-based (0 of 0), and it ranks #591 of 29,740 by population served among that same cohort.

EPA violations vs. the national water-system corpus

Public water systems serving 500+ people (EPA SDWIS)

0 Among the lowest violation counts fewer violations than 96% of 29,740 water systems

the national water-system corpus, bucketed by value

Each bar is a band; taller bars hold more water systems. The dashed line + filled bar mark this entry. Hover or tap any bar for its full count and share, and where it sits relative to this entry.

Source EPA SDWIS · 2026-05-15

How many violations vs. how serious, among peer systems

Western MWD plotted against 29 peer public water systems (500+ people served), by total violation count (x) and the share of those violations that are health-based (y). The crosshair sits at this sample's own median on each axis. A high violation count does not automatically mean a serious record: most monitoring and reporting violations are minor, not health-based.

30 public water systems (500+ people served), EPA SDWIS current release.

How to read this

Each dot is one public water system; the highlighted dot is Western MWD. A system to the right has more recorded violations; a system higher up has a larger share of those violations classified health-based rather than monitoring or reporting.

Rare but serious: few violations, but most of them are health-based.
Frequent, mostly paperwork: many violations, but mostly monitoring or reporting, not health-based.
Clean record: below-median on both counts, the tinted corner.

View all 30 systems as a list

City of Ballinger: 372 violations, 85% health-based
Nooksack Valley Water Association: 16 violations, 31% health-based
Montgomery Co RWD 12: 7 violations, 29% health-based
Irvin Water District #6: 11 violations, 27% health-based
Ticonderoga WD: 47 violations, 26% health-based
Pine Valley Plantation: 37 violations, 24% health-based
McLouth, City Of: 29 violations, 17% health-based
Kipling Oaks 1: 25 violations, 16% health-based
South Deerfield Water Supply District: 96 violations, 16% health-based
Sunset Ridge Water District: 82 violations, 15% health-based
Orange Water Dept: 136 violations, 14% health-based
Mount Pleasant Water Sys #1: 167 violations, 11% health-based
Lake Gibson Estates: 42 violations, 2% health-based
Benson Culinary Improvement District: 212 violations, 1% health-based
Conemaugh Twp Muni Auth: 567 violations, 1% health-based
Miccosukee Service Plaza: 0 violations, 0% health-based
Brazoria - Fort Bend Counties MUD 3: 0 violations, 0% health-based
Tanglewilde Thompson Place 600: 2 violations, 0% health-based
Center Water Co: 5 violations, 0% health-based
Spring Mills Elem School/Hvs: 9 violations, 0% health-based
Great Bend Industrial Park: 14 violations, 0% health-based
Glen Park Village: 19 violations, 0% health-based
Camp Is-Sho-Da: 22 violations, 0% health-based
Hamilton: 33 violations, 0% health-based
Town of Welaka: 54 violations, 0% health-based
Township of Blairstown Dpw: 61 violations, 0% health-based
McIntosh Water & Fire Pro Authority: 71 violations, 0% health-based
Clarkdale Municipal Water System: 114 violations, 0% health-based
Eureka Water Association: 273 violations, 0% health-based
Western MWD: 0 violations, 0% health-based (this system)

PFAS Testing Results (UCMR5)

Results from EPA's Fifth Unregulated Contaminant Monitoring Rule. 4 of 348 samples detected PFAS.

Contaminant	Date	Result	MRL	Status
PFOS	9/14/2023	<4.00 ppt	4.00 ppt	Not Detected
9Cl-PF3ONS	9/14/2023	<2.00 ppt	2.00 ppt	Not Detected
11Cl-PF3OUdS	9/14/2023	<5.00 ppt	5.00 ppt	Not Detected
PFUnA	9/14/2023	<2.00 ppt	2.00 ppt	Not Detected
PFHxA	9/14/2023	<3.00 ppt	3.00 ppt	Not Detected
PFDoA	9/14/2023	<3.00 ppt	3.00 ppt	Not Detected
PFNA	9/14/2023	<4.00 ppt	4.00 ppt	Not Detected
PFOA	9/14/2023	<4.00 ppt	4.00 ppt	Not Detected
ADONA	9/14/2023	<3.00 ppt	3.00 ppt	Not Detected
PFEESA	9/14/2023	<3.00 ppt	3.00 ppt	Not Detected
PFHxS	9/14/2023	<3.00 ppt	3.00 ppt	Not Detected
PFDA	9/14/2023	<3.00 ppt	3.00 ppt	Not Detected
HFPO-DA	9/14/2023	<5.00 ppt	5.00 ppt	Not Detected
PFBA	9/14/2023	<5.00 ppt	5.00 ppt	Not Detected
6:2 FTS	9/14/2023	<5.00 ppt	5.00 ppt	Not Detected
4:2 FTS	9/14/2023	<3.00 ppt	3.00 ppt	Not Detected
8:2 FTS	9/14/2023	<5.00 ppt	5.00 ppt	Not Detected
PFMPA	9/14/2023	<4.00 ppt	4.00 ppt	Not Detected
PFMBA	9/14/2023	<3.00 ppt	3.00 ppt	Not Detected
NFDHA	9/14/2023	<20.00 ppt	20.00 ppt	Not Detected
PFPeS	9/14/2023	<4.00 ppt	4.00 ppt	Not Detected
PFHpS	9/14/2023	<3.00 ppt	3.00 ppt	Not Detected
PFHpA	9/14/2023	<3.00 ppt	3.00 ppt	Not Detected
PFTrDA	9/14/2023	<7.00 ppt	7.00 ppt	Not Detected
PFPeA	9/14/2023	<3.00 ppt	3.00 ppt	Not Detected
PFBS	9/14/2023	<3.00 ppt	3.00 ppt	Not Detected
NMeFOSAA	9/14/2023	<6.00 ppt	6.00 ppt	Not Detected
PFTA	9/14/2023	<8.00 ppt	8.00 ppt	Not Detected
NEtFOSAA	9/14/2023	<5.00 ppt	5.00 ppt	Not Detected
ADONA	9/14/2023	<3.00 ppt	3.00 ppt	Not Detected
HFPO-DA	9/14/2023	<5.00 ppt	5.00 ppt	Not Detected
PFBA	9/14/2023	<5.00 ppt	5.00 ppt	Not Detected
9Cl-PF3ONS	9/14/2023	<2.00 ppt	2.00 ppt	Not Detected
4:2 FTS	9/14/2023	<3.00 ppt	3.00 ppt	Not Detected
6:2 FTS	9/14/2023	<5.00 ppt	5.00 ppt	Not Detected
11Cl-PF3OUdS	9/14/2023	<5.00 ppt	5.00 ppt	Not Detected
PFHxA	9/14/2023	<3.00 ppt	3.00 ppt	Not Detected
PFDoA	9/14/2023	<3.00 ppt	3.00 ppt	Not Detected
8:2 FTS	9/14/2023	<5.00 ppt	5.00 ppt	Not Detected
PFHxS	9/14/2023	3.40 ppt	3.00 ppt	Detected
PFUnA	9/14/2023	<2.00 ppt	2.00 ppt	Not Detected
PFHpA	9/14/2023	<3.00 ppt	3.00 ppt	Not Detected
PFBS	9/14/2023	3.00 ppt	3.00 ppt	Detected
PFDA	9/14/2023	<3.00 ppt	3.00 ppt	Not Detected
PFPeA	9/14/2023	<3.00 ppt	3.00 ppt	Not Detected
PFTrDA	9/14/2023	<7.00 ppt	7.00 ppt	Not Detected
PFTA	9/14/2023	<8.00 ppt	8.00 ppt	Not Detected
NMeFOSAA	9/14/2023	<6.00 ppt	6.00 ppt	Not Detected
PFOS	9/14/2023	<4.00 ppt	4.00 ppt	Not Detected
PFPeS	9/14/2023	<4.00 ppt	4.00 ppt	Not Detected

Population served record for Western MWD

EPA SDWIS lists 86,062 people served and 22,297 connections for this PWS, confirm the service-area footprint on the federal report before comparing to municipal census totals.

EPA SDWIS · PWS CA3310049 CA primacy agency

Sources: EPA SDWIS · California State Water Resources Control Board, Division of Drinking Water

Nationwide peers

0 violations · 86,062 served: nearest cross-state SDWIS matches.

Cross-state systems with similar served population

Nearest cross-state systems by EPA SDWIS population_served (same 500+ sitemap gate).

4 peers

What to do with Western MWD

Use this system's EPA-reported record as a starting filter, not a final verdict.

See how every tracked system in California compares on the same EPA violation measures. California systems
Check whether PFAS was detected at this system under UCMR5 testing. PFAS guide
Find and compare another public water system by name or PWSID. Search systems

EPA SDWIS and UCMR5 figures are informational only, not a substitute for a certified lab test of your own tap water.

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

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

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