01The verdict: is Grand Coteau water safe?
Grand Coteau's drinking water has significant quality concerns based on EPA testing data. With a grade of F (34/100), the system has issues across multiple categories. A water filter is recommended for all residents. The city's 1 water system serves approximately 1,650 residents using groundwater (wells).
Copper is over its legal limit
Measured at 2.00 mg/L against the EPA Action Level of 1.3 mg/L. The ledger below shows how far over — and which filter removes it.
See the measurement ↓2K people, 1 system
All figures on this page come from federal EPA compliance and testing data for the systems serving this city.
See the systems ↓17 violations in the last five years
Recent compliance history is the best predictor of future problems — the year-by-year record is below.
See the record ↓Grand Coteau's drinking water received a grade of F (34 out of 100), indicating failing water quality. The city's 1 water system serves approximately 1,650 residents using groundwater.
Lead levels were measured at 7.0 ppb (90th percentile), which is within EPA limits but above recommended levels. This system has not yet been tested for PFAS under the EPA UCMR 5 program. The system has 48 violations on record, including 21 health-based violations. 37 remain unresolved.
Grand Coteau ranks #308 out of 309 cities in Louisiana for water quality, placing it among the lowest-rated in the state. Grand Coteau 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. While lead levels are within EPA limits, they are above the recommended 5 ppb threshold that health organizations consider ideal. A point-of-use filter adds an extra layer of protection. As a small community water system, Grand Coteau may have fewer resources for advanced treatment technologies and infrastructure upgrades compared to larger utilities. The system has seen 17 violations in the past five years, suggesting a pattern of compliance challenges that residents should monitor closely.
02What's in Grand Coteau's water
Every contaminant flagged in Grand Coteau, 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.
Over Limit — EPA Action Level: 1.3 mg/L
Exceeds the EPA action level. Copper leaches from household plumbing — flush taps for 30 seconds before drinking, and consider a certified filter.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. | 7.0 | 15 | ppb | Inorganic | Safe |
| Copper (90th percentile) CopperInorganic A metal that enters drinking water mainly through corrosion of copper plumbing. Small amounts are essential for health, but excess levels are harmful. Health EffectsGastrointestinal distress (nausea, vomiting, diarrhea) at short-term high levels; liver and kidney damage from long-term exposure. EPA Limit1.3 mg/L action level Common SourcesCorrosion of copper household plumbing, erosion of natural deposits. | 2.00 | 1.3 | mg/L | Inorganic | Over Limit |
Cities ranked by 90th-percentile lead PF PFAS in Louisiana
Cities ranked by compounds detected Cu Copper in Louisiana
Cities ranked by 90th-percentile copper
03Grand Coteau'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 48 violations on record, including 21 health-based violations. 37 remain unresolved.
2 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 4 ppb since 2008. Latest reading: 7 ppb (2025) — 47% of the action level. Sampled at higher-risk homes (90th percentile).
▼ Down 0.50 mg/L since 1993. The latest reading (2 mg/L, 2023) is over the action level. Sampled at higher-risk homes (90th percentile).
04Where Grand Coteau's water comes from
Grand Coteau'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.
1,650 people
Residents served across Grand Coteau'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 1,650 people through 1 water system.
| System name | PWSID | Population | Source |
|---|---|---|---|
| TOWN OF GRAND COTEAU WATER SYSTEM | LA1097001 | 1,650 | Groundwater |
Water bodies near Grand Coteau
These water bodies shape the regional watershed and can indirectly affect groundwater quality.
05Pressure on Grand Coteau'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.
Industrial discharge
1 facility within 10 miles reported 0 lb released to surface water in the latest EPA Toxics Release Inventory. Proximity doesn't equal tap contamination — treatment and hydrology decide — but it's pressure on the watershed.
06How Grand Coteau compares
Scores for nearby Louisiana cities on one line, with the average marked.
dashed line = Louisiana average (53/100)
Grand Coteau scores 34/100 — below the Louisiana average of 53/100. Full Louisiana rankings →
43.2 / 100AJefferson, LA
85.8 / 100FNew Orleans, LA
34.1 / 100FLafayette, LA
35.1 / 100FShreveport, LA
36.5 / 100BHouma, LA
82.4 / 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 Grand Coteau's water — not generic advice.
Filter drinking & cooking water
NSF-certified water filter. Lead detected at 7.0 ppb
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 Grand Coteau 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 Grand Coteau, LA tap water safe to drink?
Grand Coteau's water quality earned a grade of F (34/100). Significant issues have been found. A water filter is strongly recommended. The city ranks #308 out of 309 cities tested in Louisiana.
What contaminants are in Grand Coteau's water?
Lead was measured at 7.0 ppb (90th percentile). 48 violations are on record.
How is Grand Coteau'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 Grand Coteau?
While lead levels are within EPA limits, a filter adds extra protection. Based on current data, basic filtration should suffice for additional peace of mind.
Where does Grand Coteau's water come from?
Grand Coteau's water is sourced from Groundwater. The city has 1 water system serving approximately 1,650 residents.
What health violations has Grand Coteau's water system had?
Grand Coteau has 21 health-based violations on record. The most recent violation was recorded in March 2025. Health-based violations mean the water exceeded EPA maximum contaminant levels (MCLs) for a regulated substance. 37 violations remain unresolved.
Is Grand Coteau's groundwater at risk of contamination?
Grand Coteau 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 48 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 Grand Coteau's water compare to other cities?
Grand Coteau ranks #308 out of 309 cities in Louisiana (better than 0% of state cities) and #15234 out of 15382 cities nationally (1th percentile). The grade of F reflects the combined assessment of violation history, lead and copper levels, PFAS contamination, and regulatory compliance.
Does Grand Coteau's small water system affect quality?
Grand Coteau's system serves approximately 1,650 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 48 violations on record.