94574
St. Helena, CA
Napa County · Napa, CA metro area
ST. HELENA, CITY OF

Is St. Helena tap water safe to drink?

Higher concern
Last tested: October 2023
Source: Official EPA UCMR5 federal monitoring data. Last tested October 2023.
CDP:
Townships:
  • Lake Berryessa CCD, CA
  • Angwin CCD, CA
  • St. Helena CCD, CA
  • Napa CCD, CA
Community:
  • Saint Helena, CA
Neighborhood:
  • Vineyard Valley Mobile Home Park

The short answer for St. Helena

St. Helena tap water has lithium above EPA guidelines at 5.4× the limit (tested July 2023). See the full report with all tested compounds and filter options.

The health risk for St. Helena

lithium has been detected above EPA limits in this water system's recent tests. A certified filter designed for this contaminant type is strongly recommended.
  • lithium above limit.
lithium concentration (µg/L) July 2023
0 µg/L 10 µg/L 100 µg/L
54.000 µg/L
Detected
µg/L
10 µg/L
EPA limit
guideline
440% above limit
Comparison
vs. guideline
EPA limit: 10 µg/L | Your water: 54.000 µg/L
Certified Filters for St. Helena Tap Water

lithium was detected above EPA limits. These filters are independently certified to reduce common drinking-water contaminants.

Water filter recommendation for St. Helena tap water: Epic Pure XP Water Filter Pitcher
Pitcher filter
Epic Pure XP Water Filter Pitcher
NSF-certified dual-layer filtration reduces 70+ contaminants including PFAS, lead, chlorine, microplastics, and bacteria.
NSF/ANSI 42, 53, 401 & P473Removes 99.99% PFASMade in USABPA-free
Best for renters or quick setup. No installation needed.
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Most elevated compounds
Compound Measurement EPA Limit Comparison
lithium
Tested: July 2023 · Stonebridge Well Site		 54.000 µg/L 10 µg/L 440% above limit
View all tested compounds

Stonebridge Well Site · Tested: July 2023

Compound Measurement EPA Limit Comparison
lithium 54.000 µg/L 10 µg/L 440% above limit
PFHxS <0.003 µg/L 0.004 µg/L Below limit
HFPO-DA <0.005 µg/L 0.01 µg/L Below limit
PFNA <0.004 µg/L 0.01 µg/L Below limit
PFHxA <0.003 µg/L 3 µg/L Below limit
PFBA <0.005 µg/L 6 µg/L Below limit
11Cl-PF3OUdS <0.005 µg/L 0.005 µg/L Below limit
4:2 FTS <0.003 µg/L 0.003 µg/L Below limit
6:2 FTS <0.005 µg/L 0.005 µg/L Below limit
8:2 FTS <0.005 µg/L 0.005 µg/L Below limit
9Cl-PF3ONS <0.002 µg/L 0.002 µg/L Below limit
ADONA <0.003 µg/L 0.003 µg/L Below limit
PFBS <0.003 µg/L 0.003 µg/L Below limit
PFDA <0.003 µg/L 0.003 µg/L Below limit
PFDoA <0.003 µg/L 0.003 µg/L Below limit
PFHpA <0.003 µg/L 0.003 µg/L Below limit
PFHpS <0.003 µg/L 0.003 µg/L Below limit
PFOA <0.004 µg/L 0.004 µg/L Below limit
PFOS <0.004 µg/L 0.004 µg/L Below limit
PFPeA <0.003 µg/L 0.003 µg/L Below limit
PFTrDA <0.007 µg/L 0.007 µg/L Below limit
PFUnA <0.002 µg/L 0.002 µg/L Below limit

Rutherford Pumping Station · Tested: October 2023

Compound Measurement EPA Limit Comparison
lithium <9.000 µg/L 10 µg/L Below limit
PFHxS <0.003 µg/L 0.004 µg/L Below limit
HFPO-DA <0.005 µg/L 0.01 µg/L Below limit
PFNA <0.004 µg/L 0.01 µg/L Below limit
PFHxA <0.003 µg/L 3 µg/L Below limit
PFBA <0.005 µg/L 6 µg/L Below limit
11Cl-PF3OUdS <0.005 µg/L 0.005 µg/L Below limit
4:2 FTS <0.003 µg/L 0.003 µg/L Below limit
6:2 FTS <0.005 µg/L 0.005 µg/L Below limit
8:2 FTS <0.005 µg/L 0.005 µg/L Below limit
9Cl-PF3ONS <0.002 µg/L 0.002 µg/L Below limit
ADONA <0.003 µg/L 0.003 µg/L Below limit
PFBS <0.003 µg/L 0.003 µg/L Below limit
PFDA <0.003 µg/L 0.003 µg/L Below limit
PFDoA <0.003 µg/L 0.003 µg/L Below limit
PFHpA <0.003 µg/L 0.003 µg/L Below limit
PFHpS <0.003 µg/L 0.003 µg/L Below limit
PFOA <0.004 µg/L 0.004 µg/L Below limit
PFOS <0.004 µg/L 0.004 µg/L Below limit
PFPeA <0.003 µg/L 0.003 µg/L Below limit
PFTrDA <0.007 µg/L 0.007 µg/L Below limit
PFUnA <0.002 µg/L 0.002 µg/L Below limit

Water Treatment Plant · Tested: October 2023

Compound Measurement EPA Limit Comparison
lithium <9.000 µg/L 10 µg/L Below limit
PFHxS <0.003 µg/L 0.004 µg/L Below limit
HFPO-DA <0.005 µg/L 0.01 µg/L Below limit
PFNA <0.004 µg/L 0.01 µg/L Below limit
PFHxA <0.003 µg/L 3 µg/L Below limit
PFBA <0.005 µg/L 6 µg/L Below limit
11Cl-PF3OUdS <0.005 µg/L 0.005 µg/L Below limit
4:2 FTS <0.003 µg/L 0.003 µg/L Below limit
6:2 FTS <0.005 µg/L 0.005 µg/L Below limit
8:2 FTS <0.005 µg/L 0.005 µg/L Below limit
9Cl-PF3ONS <0.002 µg/L 0.002 µg/L Below limit
ADONA <0.003 µg/L 0.003 µg/L Below limit
PFBS <0.003 µg/L 0.003 µg/L Below limit
PFDA <0.003 µg/L 0.003 µg/L Below limit
PFDoA <0.003 µg/L 0.003 µg/L Below limit
PFHpA <0.003 µg/L 0.003 µg/L Below limit
PFHpS <0.003 µg/L 0.003 µg/L Below limit
PFOA <0.004 µg/L 0.004 µg/L Below limit
PFOS <0.004 µg/L 0.004 µg/L Below limit
PFPeA <0.003 µg/L 0.003 µg/L Below limit
PFTrDA <0.007 µg/L 0.007 µg/L Below limit
PFUnA <0.002 µg/L 0.002 µg/L Below limit

Water utilities serving ZIP 94574

Service area boundaries are approximate and based on state filings or modeled estimates. Contact your utility to confirm exact service at a specific address.

Modeled boundaries are shown with a dashed outline.

Frequently Asked Questions about ZIP 94574 Tap Water

What contaminants are above EPA limits in ZIP 94574?

ZIP 94574 has lithium above EPA health guidelines in the latest available data at 5.4x the EPA guideline. The full table on this page lists every tested compound and its measured level.

Will boiling ZIP 94574 tap water remove lithium?

No. Boiling tap water does not remove lithium. Lithium is a dissolved mineral, so heat does not break it down and evaporation can actually concentrate it. Reverse osmosis (NSF/ANSI 58) is the most reliable at-home option for reducing lithium.

Do basic pitcher filters remove lithium?

Standard pitcher filters are not certified to reduce lithium. Reverse osmosis (NSF/ANSI 58) is the most widely available home option for reducing lithium in drinking water.

Who provides tap water in ZIP 94574?

Public records identify ST. HELENA, CITY OF as a primary water system associated with ZIP 94574. Service boundaries can vary by address, so confirm exact service with the utility.

When was ZIP 94574 tap water last tested?

The most recent test date used in this report is October 2023. EnviroClarity last refreshed this page on 2026-05-04.

Where can I find the official water quality report for ZIP 94574?

Every U.S. public water system is required to publish an annual Consumer Confidence Report (CCR). Contact ST. HELENA, CITY OF or visit their website for the latest official report covering ZIP 94574. The EPA also maintains a national CCR locator.

Primary source EPA UCMR5 (2023-2025)
Guideline source EPA drinking water standard (lithium: 10 µg/L)
Last tested October 2023
Last page update 2026-05-04

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    Nearby ZIP reports

    Data reflects publicly reported utility records from EPA datasets and local utility disclosures. This information is educational and not medical advice.

    Protect your water in St. Helena → see certified filters