Chlorine or chloramine: which does your town use?
Updated August 2026
Short answer: Covington, Mandeville, Slidell, Hammond, and the Lacombe and Cross Gates area use chloramine, and so do New Orleans, Metairie, and Kenner across the lake. Most other Northshore towns use plain chlorine. The difference decides which carbon filter actually works in your house.
The system-by-system numbers
Every public water system publishes its disinfectant and its running annual average in its yearly report. These figures come from the 2025 reports and update whenever a system publishes new ones:
| System | Disinfectant | Level (ppm RAA) |
|---|---|---|
| New Orleans, east bank | Chloramine | 3.3 |
| New Orleans, Algiers | Chloramine | 3.1 |
| Metairie and Kenner | Chloramine | 1.9 |
| Gretna | Chloramine | 2.8 |
| Marrero, Harvey, Terrytown | Chloramine | 1.9 |
| Westwego | Chloramine | 1.6 |
| Covington, city system | Chloramine | 0.9 |
| Mandeville, city system | Chloramine | 1.8 |
| Slidell, city system | Chloramine | 1.8 |
| Hammond, city system | Chloramine | 1.8 |
| Greater Hammond (Tangipahoa Water District) | Chloramine | 1.9 |
| Cross Gates and Lacombe | Chloramine | 2.0 |
| Ponchatoula | Free chlorine | 0.9 |
| Abita Springs | Free chlorine | 1.3 |
| Madisonville | Free chlorine | 0.8 |
| Western St. Tammany (Tammany Utilities) | Free chlorine | 1.2 |
| River Oaks, Covington | Free chlorine | 1.7 |
| Lake Ramsey, Covington | Free chlorine | 0.7 |
For a sense of scale, the CDC keeps swimming pools between 1 and 3 ppm of chlorine, so several of these systems deliver tap water inside pool range. The pattern runs along the causeway: the whole south shore is chloramine country, the Northshore cities run chloramine at lower levels, and the small parish and subdivision systems mostly run free chlorine. Dozens of subdivision systems publish their own numbers, which is one more reason your neighborhood matters more than your city. Look yours up and the answer is right there.
Why it changes your filter
Plain chlorine comes out with ordinary activated carbon. Chloramine is chlorine bonded with ammonia, and it grips on. Standard carbon barely touches it, which is why some homes install a filter and still taste the pool. Chloramine needs catalytic carbon, a media processed specifically to break it down. We install catalytic carbon as the standard in every municipal-water home, so the tank works no matter which chemical your system runs or switches to.
This is the single most common spec mistake in our area. If you are getting quotes, ask each company one question: which carbon are you putting in the tank, and why? The answer tells you whether they looked at your town's report.