Question 1

Which county in Louisiana has the best water quality?

Accepted Answer

Assumption Parish has the highest water quality score in Louisiana at 100.0/100 (Grade: A), based on EPA SDWIS data.

Question 2

Which county in Louisiana has the most water violations?

Accepted Answer

Winn Parish has among the lowest water quality scores in Louisiana at 86.5/100. See the individual county page for detailed violation history.

Question 3

Is the tap water safe to drink in Louisiana?

Accepted Answer

Louisiana has an average water quality score of 98.1/100 based on EPA Safe Drinking Water Act compliance data. Individual county scores vary — check your specific county's page for detailed information.

Question 4

What contaminants are found in Louisiana water supplies?

Accepted Answer

Drinking water quality varies by county and water system. The EPA Safe Drinking Water Information System (SDWIS) tracks violations for contaminants like lead, nitrates, bacteria, and disinfection byproducts. See individual county pages for specific contaminant and violation history.

County	Water Score	Grade	Violations	Violation Rate
Assumption Parish	100.0	A	0	0.0%
East Baton Rouge Parish	100.0	A	5	0.8%
Jefferson Davis Parish	100.0	C	3	7.8%
Jefferson Parish	100.0	B	6	1.4%
Lafourche Parish	100.0	A	0	0.0%
Orleans Parish	100.0	B	12	3.1%
St. Bernard Parish	100.0	A	0	0.0%
St. Charles Parish	100.0	A	0	0.0%
St. John the Baptist Parish	100.0	A	0	0.0%
Terrebonne Parish	100.0	A	0	0.0%
West Baton Rouge Parish	100.0	B	1	3.3%
West Feliciana Parish	100.0	B	1	4.8%
Beauregard Parish	99.9	D	12	24.3%
Calcasieu Parish	99.9	D	53	25.9%
East Feliciana Parish	99.9	C	4	14.4%
Lafayette Parish	99.9	F	92	30.4%
Livingston Parish	99.9	F	49	31.5%
Pointe Coupee Parish	99.9	F	10	32.3%
Rapides Parish	99.9	D	35	21.5%
Iberia Parish	99.8	F	39	52.0%
St. Tammany Parish	99.8	F	102	42.4%
Tangipahoa Parish	99.8	F	58	45.4%
Vernon Parish	99.8	F	28	42.7%
Avoyelles Parish	99.6	F	42	79.5%
Caddo Parish	99.6	F	235	95.9%
Catahoula Parish	99.6	F	11	86.6%
St. Helena Parish	99.6	F	10	96.1%
St. Landry Parish	99.6	F	108	97.0%
Vermilion Parish	99.6	F	56	79.3%
Washington Parish	99.6	F	29	88.2%
Ascension Parish	99.5	F	36	112.5%
Bossier Parish	99.5	F	159	113.7%
St. James Parish	99.5	F	22	98.4%
Webster Parish	99.5	F	51	102.1%
Ouachita Parish	99.4	F	228	122.3%
St. Martin Parish	99.4	F	99	133.9%
Allen Parish	99.3	F	46	142.8%
Claiborne Parish	99.3	F	29	144.6%
Franklin Parish	99.3	F	37	143.7%
Acadia Parish	99.2	F	110	183.6%
Evangeline Parish	99.2	F	70	163.8%
West Carroll Parish	99.2	F	24	165.2%
Iberville Parish	99.0	F	87	212.5%
Madison Parish	99.0	F	29	214.1%
St. Mary Parish	99.0	F	131	209.2%
Lincoln Parish	98.8	F	154	254.4%
Plaquemines Parish	98.6	F	101	314.8%
Richland Parish	98.4	F	83	339.1%
Morehouse Parish	97.4	F	178	557.2%
Natchitoches Parish	97.0	F	291	652.2%
De Soto Parish	96.9	F	236	686.0%
Grant Parish	96.6	F	191	732.9%
East Carroll Parish	96.4	F	63	780.7%
Red River Parish	94.3	F	153	1240.0%
Jackson Parish	94.0	F	237	1317.0%
Caldwell Parish	93.9	F	217	1334.8%
Concordia Parish	93.7	F	362	1382.1%
Cameron Parish	92.7	F	173	1600.8%
Bienville Parish	92.6	F	257	1605.5%
Sabine Parish	91.3	F	747	1903.5%
Tensas Parish	90.5	F	173	2075.3%
Union Parish	87.7	F	876	2675.7%
Winn Parish	86.5	F	504	2935.0%
LaSalle Parish	—	—	—	—

Louisiana Water Quality

Best Water Quality

Lowest Water Quality

All Louisiana Counties

Concerned about your water quality?

Explore more data for Louisiana