Water hardness in Louisiana
Louisiana has a median ambient water hardness of 92 mg/L, which is 5.4 grains per gallon and classes as moderately hard. That is the middle of 83,426 samples across 64 counties.
This is ambient water, not tap water. These figures come from samples taken from wells, streams and springs by USGS, EPA and state agencies. Municipal utilities treat, blend and sometimes soften water before it reaches a tap, so a city supply can be considerably softer than the ground beneath it. Treat this as a good guide for a private well and an approximate one for city water. Your utility's annual water quality report gives the real number for a municipal tap, and a test strip gives it for yours.
Every monitored county in Louisiana
Ranked hardest first. The middle 50% column shows how much the samples within a county vary, which matters more than the median where a county spans two geologies.
| County | mg/L | gpg | Class | Middle 50% | Samples |
|---|---|---|---|---|---|
| St. Bernard Parish | 940 | 54.9 | Very hard | 290 to 2,282 | 1,327 |
| Cameron Parish | 780 | 45.6 | Very hard | 110 to 2,880 | 1,470 |
| Red River Parish | 250 | 14.6 | Very hard | 67 to 460 | 1,449 |
| Terrebonne Parish | 240 | 14 | Very hard | 119 to 1,660 | 2,661 |
| Orleans Parish | 210 | 12.3 | Very hard | 120 to 700 | 1,864 |
| Franklin Parish | 196 | 11.4 | Very hard | 61 to 330 | 768 |
| Plaquemines Parish | 174 | 10.2 | Hard | 140 to 560 | 2,072 |
| Jefferson Parish | 170 | 9.9 | Hard | 113 to 320 | 1,622 |
| Lafourche Parish | 162 | 9.5 | Hard | 110 to 2,700 | 1,676 |
| Bossier Parish | 150 | 8.8 | Hard | 65 to 320 | 2,568 |
| Natchitoches Parish | 150 | 8.8 | Hard | 28 to 450 | 1,874 |
| Vermilion Parish | 148 | 8.6 | Hard | 60 to 320 | 1,939 |
| St. Charles Parish | 147 | 8.6 | Hard | 110 to 190 | 1,572 |
| Iberia Parish | 144 | 8.4 | Hard | 82 to 393 | 902 |
| Iberville Parish | 140 | 8.2 | Hard | 110 to 170 | 1,633 |
| St. James Parish | 140 | 8.2 | Hard | 110 to 180 | 785 |
| West Feliciana Parish | 140 | 8.2 | Hard | 110 to 160 | 1,629 |
| Avoyelles Parish | 130 | 7.6 | Hard | 66 to 290 | 1,823 |
| St. Mary Parish | 130 | 7.6 | Hard | 99 to 160 | 3,261 |
| Madison Parish | 129 | 7.5 | Hard | 51 to 229 | 410 |
| Pointe Coupee Parish | 128 | 7.5 | Hard | 97 to 160 | 1,226 |
| Calcasieu Parish | 120 | 7 | Moderately hard | 42 to 435 | 2,914 |
| Assumption Parish | 114 | 6.7 | Moderately hard | 90 to 149 | 362 |
| Richland Parish | 110 | 6.4 | Moderately hard | 49 to 250 | 682 |
| West Carroll Parish | 98 | 5.7 | Moderately hard | 46 to 210 | 372 |
| St. Martin Parish | 97 | 5.7 | Moderately hard | 51 to 140 | 781 |
| St. Landry Parish | 96 | 5.6 | Moderately hard | 51 to 154 | 1,491 |
| Ascension Parish | 94 | 5.5 | Moderately hard | 48 to 160 | 744 |
| Acadia Parish | 92 | 5.4 | Moderately hard | 53 to 160 | 882 |
| Caddo Parish | 91 | 5.3 | Moderately hard | 39 to 350 | 2,427 |
| Rapides Parish | 91 | 5.3 | Moderately hard | 16 to 370 | 4,214 |
| West Baton Rouge Parish | 91 | 5.3 | Moderately hard | 4 to 166 | 1,051 |
| Lafayette Parish | 86 | 5 | Moderately hard | 49 to 124 | 541 |
| East Carroll Parish | 85 | 5 | Moderately hard | 71 to 150 | 311 |
| Concordia Parish | 81 | 4.7 | Moderately hard | 51 to 124 | 814 |
| St. John the Baptist Parish | 76 | 4.4 | Moderately hard | 33 to 187 | 671 |
| Tensas Parish | 71 | 4.1 | Moderately hard | 61 to 90 | 316 |
| Jefferson Davis Parish | 56 | 3.3 | Soft | 36 to 94 | 895 |
| Catahoula Parish | 52 | 3 | Soft | 30 to 98 | 2,250 |
| De Soto Parish | 46 | 2.7 | Soft | 24 to 86 | 741 |
| Evangeline Parish | 44 | 2.6 | Soft | 17 to 110 | 596 |
| Morehouse Parish | 43 | 2.5 | Soft | 18 to 94 | 1,077 |
| Webster Parish | 36 | 2.1 | Soft | 20 to 68 | 679 |
| Sabine Parish | 35 | 2 | Soft | 27 to 41 | 759 |
| St. Tammany Parish | 34 | 2 | Soft | 12 to 258 | 4,279 |
| Caldwell Parish | 32 | 1.9 | Soft | 21 to 60 | 593 |
| LaSalle Parish | 25 | 1.5 | Soft | 16 to 50 | 1,051 |
| Ouachita Parish | 25 | 1.5 | Soft | 7 to 44 | 1,680 |
| Beauregard Parish | 24 | 1.4 | Soft | 15 to 37 | 1,120 |
| Union Parish | 24 | 1.4 | Soft | 14 to 50 | 900 |
| Grant Parish | 21 | 1.2 | Soft | 9 to 120 | 1,412 |
| Winn Parish | 20 | 1.2 | Soft | 8 to 36 | 646 |
| Claiborne Parish | 19 | 1.1 | Soft | 12 to 35 | 396 |
| Livingston Parish | 19 | 1.1 | Soft | 11 to 34 | 1,210 |
| Tangipahoa Parish | 18 | 1.1 | Soft | 10 to 41 | 1,545 |
| Bienville Parish | 17 | 1 | Soft | 10 to 35 | 757 |
| East Baton Rouge Parish | 17 | 1 | Soft | 5 to 60 | 2,628 |
| Vernon Parish | 16 | 0.9 | Soft | 8 to 32 | 1,723 |
| Allen Parish | 14 | 0.8 | Soft | 10 to 34 | 1,220 |
| East Feliciana Parish | 14 | 0.8 | Soft | 10 to 20 | 316 |
| Washington Parish | 13 | 0.8 | Soft | 10 to 18 | 1,154 |
| Jackson Parish | 12 | 0.7 | Soft | 4 to 22 | 291 |
| Lincoln Parish | 12 | 0.7 | Soft | 4 to 22 | 310 |
| St. Helena Parish | 6 | 0.4 | Soft | 4 to 8 | 94 |
Source: Water Quality Portal (USGS, EPA and state agencies), waterqualitydata.us, retrieved 2026-09-19. 2,904,346 samples across 3,110 counties.
What this means for a household in Louisiana
At 5.4 grains per gallon, a family of four would need a softener of about 16,000 grains to regenerate roughly weekly, using around 221 lb of salt a year. Size it for your own household.
64 of these counties include well samples, so the figures are a reasonable guide for private well water there. Municipal supplies in the same counties may be softer, because utilities often blend or treat.
Hardness follows geology rather than borders. Where a county sits on limestone or dolomite the water is hard; on granite, basalt or sandstone it is soft. That is why neighbouring counties in this table can differ by a factor of several.