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Water Quality Lookup / California / San Mateo County / ESTERO MUNICIPAL IMPROVEMENT DISTRICT
EPA SDWIS ยท San Mateo County, California

ESTERO MUNICIPAL IMPROVEMENT DISTRICT Water Quality Report

Serving roughly 36,556 people in San Mateo County, California.

Data current as of July 2026
๐Ÿ”Straight from EPA
๐ŸงชReal Lab Results
๐Ÿ“…Updated Quarterly
๐Ÿ Local Expertise
Results for ESTERO MUNICIPAL IMPROVEMENT DISTRICT

1 water provider directly on file, serving roughly 36,556 people in San Mateo County, California.

Quick answer: ESTERO MUNICIPAL IMPROVEMENT DISTRICT has no violations on file and no single reading stands out against its peers (113 other providers in this area). It serves roughly 36,556 people, and the full breakdown below reflects everything EPA and California have on record for it.
Utility ESTERO MUNICIPAL IMPROVEMENT DISTRICT Population served 36,556 Owner Local government
No violations on file

Contaminants found

Metals
Naturally occurring or corrosion-related elements, e.g. lead, arsenic, copper
Lead Summary
Detected: 0 mg/L (ppm)
12/31/2025
Lead
Detected: 11 UG/L (ppb)
9/10/2025
A metal that can leach from old pipes, solder, and fixtures. Current medical guidance holds there is no truly safe level of lead exposure, especially for children and pregnant women.
Copper, Free
Detected: 89.7 UG/L (ppb)
9/9/2025
Disinfection Byproducts
Formed when chlorine used to disinfect water reacts with organic matter
Totalhaloaceticacids (HAA5)
Detected: 37.1 UG/L (ppb)
7/15/2025
TTHM
Detected: 51 UG/L (ppb)
7/15/2025
A group of disinfection byproducts formed when chlorine reacts with organic matter. Long-term exposure above the legal limit has been linked to increased cancer risk in some studies.
Chloroform
Detected: 51 UG/L (ppb)
7/15/2025
One of the individual trihalomethane disinfection byproducts, formed when chlorine reacts with organic matter.
Bromodichloromethane
Detected: 1 UG/L (ppb)
7/15/2025
Dibromochloromethane
Detected: 1.11 UG/L (ppb)
1/14/2025
Other
Additional substances tested that don't fit neatly into the categories above
Dichloroaceticacid
Detected: 21 UG/L (ppb)
7/15/2025
Trichloroaceticacid
Detected: 16.1 UG/L (ppb)
7/15/2025
Filtration considerations: See the table below for how whole-house carbon, under-sink reverse osmosis, and under-sink carbon systems compare against what's actually on file here. These are general system types, not a specific product recommendation.
Contaminant Whole-House Carbon Under-Sink RO Under-Sink Carbon
Total Trihalomethanes (TTHM)YesYesYes
Haloacetic Acids (HAA5)YesYesYes
ChloroformYesYesYes
Chlorine / TasteYesYesYes
Sediment / TurbidityYesYesYes
TrichloroethyleneYesYesYes
TetrachloroethyleneYesYesYes
cis-1,2-DichloroethyleneYesYesYes
1,1-DichloroethyleneYesYesYes
BromoformYesYesYes
BromodichloromethaneYesYesYes
DibromochloromethaneYesYesYes
1,1,2-TrichloroethaneYesYesYes
Vinyl ChlorideYesYesYes
Carbon TetrachlorideYesYesYes
BenzeneYesYesYes
TolueneYesYesYes
XyleneYesYesYes
Totalhaloaceticacids (HAA5)YesYesYes
LeadPartialYesPartial
ArsenicPartialYesPartial
Chromium-6 (Hexavalent)PartialYesPartial
CopperPartialYesPartial
Combined UraniumPartialYesPartial
PFOAPartialYes*Partial
PFOSPartialYes*Partial
NitratePartialYesPartial
Combined RadiumPartialYesPartial
DichloroaceticacidPartialYesPartial
TrichloroaceticacidPartialYesPartial
Copper, FreePartialYesPartial
Coliform Bacteria (indicator)NoYesNo

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What is TTHM? Understanding EPA Violation Status Is Chromium-6 Dangerous? Whole-House vs. Under-Sink Filtration Lead and Copper in Drinking Water What is PFAS? Arsenic and Uranium Explained Nitrate and Fluoride Explained Water Hardness, pH, and Turbidity What is Coliform Bacteria?