Water report · not indexed
What is in the water at 94544
3 public water systems serve this ZIP code in the federal records. Everything below comes from EPA monitoring data, and everything missing is named.
ALAMEDA COUNTY WATER DISTRICT
PWSID CA0110001 · CA · serves 344,000 people
PFAS and lithium
Sampled, nothing detected. Tested for 30 compounds under UCMR 5 with none found at or above its reporting limit. A reporting limit is the lowest concentration the method can measure, so this means “below that” rather than “zero”.
Health-based violations
No open health-based violation on record. This covers MCL, treatment technique and MRDL violations in SDWIS that have not been returned to compliance. It excludes monitoring and reporting violations, which are the large majority nationally, so this is not “no violations”, and SDWIS completeness varies by state.
Hardness
Median hardness 199 mg/L as CaCO₃, measured at 2 stations serving this system across 8 results, 2017-04-04 to 2022-04-04. Measured in the water source and distribution area, not at a tap, and not in your home.
EAST BAY MUD
PWSID CA0110005 · CA · serves 1,442,800 people
PFAS and lithium
2 compounds detected at or above the reporting limit under EPA’s UCMR 5 monitoring, across 4 samples.
| Compound | Highest detected | Samples | Most recent |
|---|---|---|---|
| PFBA | 0.0052 µg/L | 2 | 8/16/2023 |
| PFHxA | 0.0035 µg/L | 2 | 11/18/2025 |
A detection is a measurement, not a violation and not a health finding. EPA states that UCMR 5 results do not indicate compliance or non-compliance with any limit.
Health-based violations
No open health-based violation on record. This covers MCL, treatment technique and MRDL violations in SDWIS that have not been returned to compliance. It excludes monitoring and reporting violations, which are the large majority nationally, so this is not “no violations”, and SDWIS completeness varies by state.
Hardness
Median hardness 362 mg/L as CaCO₃, measured at 14 stations serving this system across 82 results, 2017-04-03 to 2017-05-11. Measured in the water source and distribution area, not at a tap, and not in your home.
CITY OF HAYWARD
PWSID CA0110006 · CA · serves 162,954 people
PFAS and lithium
Sampled, nothing detected. Tested for 30 compounds under UCMR 5 with none found at or above its reporting limit. A reporting limit is the lowest concentration the method can measure, so this means “below that” rather than “zero”.
Health-based violations
No open health-based violation on record. This covers MCL, treatment technique and MRDL violations in SDWIS that have not been returned to compliance. It excludes monitoring and reporting violations, which are the large majority nationally, so this is not “no violations”, and SDWIS completeness varies by state.
Hardness
Median hardness 347 mg/L as CaCO₃, measured at 3 stations serving this system across 14 results, 2017-04-03 to 2022-04-20. Measured in the water source and distribution area, not at a tap, and not in your home.
What this report cannot tell you
Every figure describes water at a sampling point: a treatment plant, an entry point to the distribution system, or a monitoring station. None of it describes water arriving at your tap. Plumbing between the two can add lead and copper, and if your home was built before 1986 a test kit tells you something no federal dataset can.
Sources: EPA UCMR 5 occurrence (final release, frozen July 2026) · EPA SDWIS health-based violations · USGS and state monitoring via the Water Quality Portal · EPA Public Water System Service Area Boundaries v3. Compiled 2026-09-01.