94578
San Leandro, CA
Alameda County · San Francisco-Oakland-Fremont, CA metro area
EAST BAY MUD

Is tap water in Castro Valley (94578) safe to drink?

Some concern
Last tested: July 2024
Source: Official EPA UCMR5 federal monitoring data. Last tested July 2024.
CDPs:
Township:
  • Hayward CCD, CA
Neighborhoods:
  • Longwood - Winton Grove
  • Upper B Street
  • Russell City
  • San Leandro
  • Brookfield Village
  • Elmhurst

The short answer for Castro Valley (94578)

San Leandro tap water has 3 detected contaminants, currently below EPA limits (tested January 2024). 6:2 FTS measured closest to the threshold. See the full compound-by-compound report.

The health risk for San Leandro

PFAS traces were detected in local water tests, though levels are currently below EPA limits. Since no amount of PFAS is considered completely safe by health researchers, a certified filter adds a meaningful layer of protection, especially for children.
  • PFAS or other chemicals detected; no confirmed exceedances in multiple samples.
6:2 FTS concentration (µg/L) January 2024
0 µg/L 0.005 µg/L 0.01 µg/L
0.005 µg/L
Detected
µg/L
0.005 µg/L
EPA limit
guideline
100% of limit
Comparison
vs. guideline
EPA limit: 0.005 µg/L | Your water: 0.005 µg/L
Add a Layer of Protection for San Leandro Tap Water

6:2 FTS (a PFAS 'forever chemical') was detected below EPA limits. A certified filter can still add an extra layer of protection.

Water filter recommendation for San Leandro 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.
Get the Epic Pure XP →
Most elevated compounds
Compound Measurement EPA Limit Comparison
6:2 FTS
Tested: January 2024 · Walnut Creek WTP		 0.005 µg/L 0.005 µg/L 100% of limit
6:2 FTS
Tested: August 2023 · Upper San Leandro WTP		 0.005 µg/L 0.005 µg/L 100% of limit
View all tested compounds

Lafayette WTP · Tested: July 2024

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

Orinda TP · Tested: January 2024

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

San Pablo WTP · Tested: November 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
PFUnA <0.002 µg/L 0.002 µg/L Below limit

Sobrante WTP · Tested: Multiple dates

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

Upper San Leandro WTP · Tested: Multiple dates

Compound Measurement EPA Limit Comparison
6:2 FTS 0.005 µg/L 0.005 µg/L 100% of limit
PFBA 0.005 µg/L 6 µg/L 0.1% of limit
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
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

Walnut Creek WTP · Tested: January 2024

Compound Measurement EPA Limit Comparison
6:2 FTS 0.005 µg/L 0.005 µg/L 100% of limit
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 94578

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 94578 Tap Water

What's in ZIP 94578 tap water?

ZIP 94578 has 3 detected contaminants below EPA limits in this dataset. 6:2 FTS measured closest to its guideline.

Will boiling ZIP 94578 tap water remove 6:2 FTS?

Boiling tap water can kill many pathogens, but it does not remove most chemical contaminants tracked in EPA monitoring. Several dissolved contaminants can even concentrate as water evaporates. For the chemical contaminants reported in ZIP 94578, a certified filter is more reliable.

Do basic pitcher filters remove 6:2 FTS?

Basic pitcher filters are typically rated for chlorine, taste, and odor (NSF/ANSI 42), not for the broader list of contaminants tracked in EPA monitoring. Match the certification (NSF/ANSI 42, 53, 58, or P473) to the specific compounds listed in this report before assuming a filter helps.

Who provides tap water in ZIP 94578?

Public records identify EAST BAY MUD as a primary water system associated with ZIP 94578. Service boundaries can vary by address, so confirm exact service with the utility.

When was ZIP 94578 tap water last tested?

The most recent test date used in this report is July 2024. EnviroClarity last refreshed this page on 2026-05-04.

Where can I find the official water quality report for ZIP 94578?

Every U.S. public water system is required to publish an annual Consumer Confidence Report (CCR). Contact EAST BAY MUD or visit their website for the latest official report covering ZIP 94578. The EPA also maintains a national CCR locator.

Primary source EPA UCMR5 (2023-2025)
Guideline source EPA drinking water standard (PFTrDA: 0,007 µg/L)
Last tested July 2024
Last page update 2026-05-04

Check another ZIP code

    Nearby ZIP reports

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

    Filter San Leandro tap water → see certified options