Well Water in Zapata County: What to Test and Why

High Risk
Testing Strongly Recommended 88 well tests on record
Top Concerns in This County
Iron Manganese

Why This Happens Here

Groundwater in Zapata County contains iron, manganese, and arsenic. Iron and manganese are present at levels that exceed EPA health standards, so well owners should have these checked.

These metals come from the rock and sediment below the surface. The Texas coastal uplands aquifer system in this area contains rocks and soil naturally rich in iron and manganese minerals. When water sits underground and moves slowly through these materials, it dissolves the metals and carries them into your well.

Groundwater in this county is notably high in iron. This metal comes from minerals in the rocks that make up the aquifer system in this region. Iron is common in wells across Zapata County.

What This Means for You

Wells in Zapata County commonly have iron and manganese at levels that exceed EPA health standards. Iron in drinking water can cause problems with your blood and organs over time. Manganese can affect your brain and nervous system, especially in children. Arsenic is also a concern in some county wells and poses serious health risks with long-term exposure.

Iron in county well water leaves brown or orange stains on sinks, toilets, and laundry. It can make water taste metallic and leave buildup in pipes. Manganese causes similar staining and can create a dark color in water. These minerals can also reduce how long water heaters and other appliances last.

We recommend a comprehensive water test to find out exactly what is in your well, since every well is different and yours may have higher or lower levels than the county average. Testing is the only way to know what needs treatment. A comprehensive metals and minerals panel typically costs between two hundred and four hundred dollars. Iron and manganese can be removed with filters or other treatment systems designed for your specific water.

Not sure if your well is affected? Get certified results in 5–7 days.

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Contaminant Detection Data

Contaminant Samples % Above MCL Distribution Confidence Risk
Iron 39 38%
Moderate High
Manganese 33 15%
Moderate High
Arsenic 33 0%
Moderate Low
Fluoride 83 0%
Moderate Low
HFPO-DA (GenX) ⓘ municipal 1 0%
Low Safe
Lead 33 0%
Moderate Safe
Nitrate 16 0%
Moderate Low
PFHxS ⓘ municipal 1 0%
Low Safe
PFNA ⓘ municipal 1 0%
Low Safe
PFOA ⓘ municipal 1 0%
Low Safe
PFOS ⓘ municipal 1 0%
Low Safe
Uranium 5 0%
Low Safe
PFBS ⓘ municipal 1
Low Safe

MCL = Maximum Contaminant Level (EPA limit for public water; used as benchmark for private wells). Distribution shows % of sampled wells in each concentration band. Methodology.
* Microbial contaminants (E. coli, coliform) reflect only samples from the last 10 years.

Data shows potential risk — a certified test confirms whether your water is affected.

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