Water Quality in San Marcos, TX (78666)
EPA violation data for public water systems serving ZIP code 78666.
Active Health Violations
10 health-based violations found in the past 5 years, with at least one still unresolved. Contaminant levels have exceeded federal safety limits. Consider testing your tap water independently.
More violations than 88% of US ZIP codes.
Based on EPA compliance data. Not a substitute for an official water quality report from your utility.
88,583
Population
38
Water Systems
38
Violations (5yr)
10
Health-Based
Location
Loading map...
Water Systems Serving This Area (38)
New Braunfels Utilities
All resolvedCity Of San Marcos
Green Valley Sud
All resolvedCity Of Kyle
Clwsc Canyon Lake Shores
3 health-basedTexas State University - San Marcos
City Of Schertz
Springs Hill Sud
2 health-basedGoforth Sud
2 health-basedSjwtx Triple Peak Plant
All resolvedCity Of Seguin
1 health-basedCrystal Clear Sud
City Of Cibolo
County Line Sud
All resolvedCity Of Lockhart
Green Haven Estates
Promiseland Church San Marcos
1 health-basedSan Marcos Baptist Academy
1 health-basedPats Grocery
Wonderland School Water System
All resolvedStringtown Wsc
Texas State University - Freeman Center
Moss Cliff Rest
Sunny Acres Mobile Home Park
Leisure Camp
Roughhouse Brewery
Middleton Brewing
Hughson Meat Co
John C Storts Iii
Devils Backbone Club
Moss Cliff Restaurant
H20 To Go
Pecan Park Campground
Alliance Regional Water Authority
Diamond Pure Water
City Of San Marcos Oak Ridge Estates
Crystal Clear Wsc Staples Farmers
Alliance Regional Water Authority 1b
Contaminants Found
Missed testing deadlines — not a detection of bacteria.
Lead and copper testing requirement. Lead exposure can cause developmental harm in children.
Annual water quality report delivery requirement.
Used to disinfect water — generally safe at regulated levels.
Lead & Copper Levels
Lead (Pb)
Within limitSampled: Jul 2025
How Does This Compare?
San Marcos (78666) has more violations than 88% of US ZIP codes. The national average is 18.87 violations per ZIP over 5 years. This ZIP has 38.
Recommended Water Filters
Based on health-based violations detected in your area, these filter types are commonly used to address similar contaminants. Consult your water utility's Consumer Confidence Report for the most current data.
Reverse Osmosis System
Highly effective at removing heavy metals, dissolved solids, and a wide range of contaminants. Recommended for homes with lead or arsenic concerns.
Targets:Lead, Copper, Arsenic, Mercury, Cadmium
Look for:NSF/ANSI 58 certified
Activated Carbon Filter
Excellent for removing chlorine, chloramine, and disinfection byproducts like THMs and HAAs. Available as pitcher filters, countertop, or under-sink units.
Targets:THMs, HAAs, Chlorine, Chloramine, Taste & Odor
Look for:NSF/ANSI 42 & 53 certified
Always look for filters certified by NSF International for the specific contaminants you want to remove. This is general educational information, not an endorsement of any specific product.