01The verdict: is La Coste water safe?
La Coste's drinking water has significant quality concerns based on EPA testing data. With a grade of A- (88.9/100), the system has issues across multiple categories. A water filter is recommended for all residents. The city's 1 water system serves approximately 1,488 residents using groundwater (wells).
4 unresolved violations on record
EPA records show open compliance items for this system. Most are administrative, but unresolved items are worth watching.
See what was cited ↓Lead is well under the limit
90th-percentile lead is 4.6 ppb — beneath the 15 ppb federal action level and under the 5 ppb watch threshold.
See the trend ↓Check back after the next refresh
EPA data updates on a rolling basis; we fold in new samples and violations every month.
Get alerts ↓La Coste's drinking water received a grade of A- (88.9 out of 100), indicating good water quality. The city's 1 water system serves approximately 1,488 residents using groundwater.
Lead levels were measured at 4.6 ppb (90th percentile), well within EPA limits. This system has not yet been tested for PFAS under the EPA UCMR 5 program. The system has 11 violations on record, including 0 health-based violations. 4 remain unresolved.
La Coste ranks #69 out of 1067 cities in Texas for water quality, placing it one of the best in the state. La Coste relies on groundwater, which is generally less vulnerable to surface contamination but can be affected by naturally occurring minerals like arsenic and nitrate, as well as agricultural and industrial runoff. As a small community water system, La Coste may have fewer resources for advanced treatment technologies and infrastructure upgrades compared to larger utilities.
02What's in La Coste's water
Every contaminant flagged in La Coste, on one shared scale: distance to its own legal limit. The red line is the limit — anything past it is out of compliance, and the closer a bar gets, the less headroom the system has.
Full contaminants report
| Contaminant | Detected Level | EPA Limit | Unit | Category | Status |
|---|---|---|---|---|---|
| Lead (90th percentile) LeadHeavy Metal A toxic heavy metal that can leach into drinking water from older pipes, solder, and fixtures. No amount of lead in water is considered safe. Health EffectsBrain and nervous system damage in children, kidney damage, high blood pressure, and reproductive problems in adults. EPA Limit15 ppb action level Common SourcesCorrosion of lead pipes, lead solder, brass faucets, and household plumbing. | 4.6 | 15 | ppb | Inorganic | Safe |
Cities ranked by 90th-percentile lead PF PFAS in Texas
Cities ranked by compounds detected Cu Copper in Texas
Cities ranked by 90th-percentile copper
03La Coste's ten-year track record
Each box is one year. A green check means no EPA violations; a numbered badge counts that year's violations — red if any were health-based, amber if they were monitoring or paperwork issues. The system has 11 violations on record, including 0 health-based violations. 4 remain unresolved.
9 of the last ten years were clean. The numbered years had EPA violations — red when any were health-based, amber when they were paperwork or missed-testing issues.
▲ Up 2.8 ppb since 1993. Latest reading: 4.6 ppb (2024) — 31% of the action level. Sampled at higher-risk homes (90th percentile).
04Where La Coste's water comes from
La Coste's drinking water is drawn from underground aquifers through wells.
Groundwater
Underground aquifers reached by wells — naturally filtered, but can carry minerals like arsenic and nitrate.
Local treatment
Groundwater generally needs less treatment — typically disinfection and, where needed, mineral removal.
1 system
1 water system, operated under local government ownership.
1,488 people
Residents served across La Coste's service area.
Groundwater is naturally filtered through rock and soil layers, generally requiring less treatment than surface water. However, it can contain naturally occurring contaminants like arsenic, radon, and minerals. Agricultural activity, septic systems, and industrial operations near well fields can introduce nitrates, pesticides, and volatile organic compounds. The system is operated by local government ownership and serves approximately 1,488 people through 1 water system.
| System name | PWSID | Population | Source |
|---|---|---|---|
| CITY OF LA COSTE | TX1630004 | 1,488 | Groundwater |
Water bodies near La Coste
These water bodies shape the regional watershed and can indirectly affect groundwater quality.
05Pressure on La Coste's watershed
Outside forces that shape what reaches the treatment plant. None of these is a verdict on the tap by itself — but each adds pressure worth knowing about.
Flood & storm history
2 federal disaster declarations on record for Medina County. Flooding and severe storms can overwhelm treatment plants, cause sewage overflows, and push runoff into supplies.
Drought
Medina County is in D1 (moderate drought) per the U.S. Drought Monitor (week of Jul 2026). Drought can raise disinfection-byproduct levels and taste/odor issues as utilities draw from lower reservoirs.
06How La Coste compares
Scores for nearby Texas cities on one line, with the average marked.
dashed line = Texas average (46/100)
La Coste scores 88.9/100 — above the Texas average of 46/100. It outscores 10 of 10 nearby cities. Full Texas rankings →
27.8 / 100FSan Antonio, TX
33.1 / 100FAustin, TX
31.2 / 100FDallas, TX
36.2 / 100FFort Worth, TX
34.5 / 100FEl Paso, TX
35.8 / 100
Compare all cities in the county — grades, violations, and contaminant data side by side.→
07What to do at home
Steps matched to what testing actually found in La Coste's water — not generic advice.
A basic carbon filter still helps
La Coste's water meets federal standards, but a simple carbon filter improves taste and adds a margin of safety against short-term issues.
Compare tested filters →Flush taps & check your service line
Lead leaches from pipes as water sits. Run cold water 30 seconds before drinking (especially mornings), and ask the utility whether your address still has a lead service line.
Lead risks explained →Watch for La Coste alerts
We refresh EPA data monthly and surface new violations, advisories, and boil-water notices for your county on this page.
All water alerts →Frequently asked questions
Is La Coste, TX tap water safe to drink?
La Coste's water quality earned a grade of A- (88.9/100). The water generally meets EPA standards and is considered safe for consumption. The city ranks #69 out of 1067 cities tested in Texas.
What contaminants are in La Coste's water?
Lead was measured at 4.6 ppb (90th percentile). 11 violations are on record.
How is La Coste's water quality grade calculated?
The grade is based on four factors: violation history (40%), lead and copper levels (25%), PFAS contamination (25%), and regulatory compliance (10%). The score is also adjusted based on how complete the available data is. See our methodology page for full details.
Do I need a water filter in La Coste?
Based on current data, basic filtration should suffice for additional peace of mind.
Where does La Coste's water come from?
La Coste's water is sourced from Groundwater. The city has 1 water system serving approximately 1,488 residents.
Is La Coste's groundwater at risk of contamination?
La Coste uses groundwater, which can be affected by naturally occurring contaminants like arsenic, radon, and nitrate, as well as agricultural runoff and industrial activity. The system has 11 violations on record that may relate to groundwater quality. Groundwater systems are generally less susceptible to surface contamination but should be monitored for emerging contaminants like PFAS.
How does La Coste's water compare to other cities?
La Coste ranks #69 out of 1067 cities in Texas (better than 94% of state cities) and #3154 out of 15382 cities nationally (80th percentile). The grade of A- reflects the combined assessment of violation history, lead and copper levels, PFAS contamination, and regulatory compliance.
Does La Coste's small water system affect quality?
La Coste's system serves approximately 1,488 residents. Small community water systems (under 3,300 people) may have fewer financial resources for infrastructure upgrades and advanced treatment technologies. However, they are held to the same EPA drinking water standards as larger systems. This system has 11 violations on record.