City of Slidell Water Supply
What EPA’s and CDC’s records show in this utility’s water: PFAS and lithium; nitrate, arsenic and other regulated chemicals; lead and copper; and violations since 2016, with the certification that handles each result.
- Serves
- 35,547 people
- Connections
- 11,849
- Water source
- Groundwater
- Based in
- Slidell, LA
- County
- St. Tammany Parish
- Owner
- Local government
The short answer
1 result is above EPA’s health benchmark. The worst: Lithium, above EPA’s health benchmark. 1 health-based violation since 2016.
What was found
PFAS and lithium: EPA UCMR 5, samples taken from Oct. 16, 2024 to April 21, 2025.
Haloacetic acids (HAA5), total trihalomethanes (TTHM) and nitrate: Louisiana’s yearly averages per water system, as CDC’s Environmental Public Health Tracking Network publishes them, 2020 to 2022, with EPA’s 2012 to 2019 file for earlier years.
Fluoride, arsenic, chromium (total) and uranium: EPA’s compliance monitoring file, samples taken from Sept. 10, 2013 to July 9, 2019. Newer results are in the utility’s annual water quality report.
PFAS: None of the six PFAS in EPA’s 2024 drinking water rule was found in this utility’s samples. None of the other 23 PFAS tested for was found either.
EPA’s 2024 PFAS rule, compound by compound
| PFAS | EPA’s limit | Result |
|---|---|---|
| PFOA | 4.0 ppt | Not foundNot found in any of 14 samples, below 4 ppt |
| PFOS | 4.0 ppt | Not foundNot found in any of 14 samples, below 4 ppt |
| PFHxS | 10 ppt | Not foundNot found in any of 14 samples, below 3 ppt |
| PFNA | 10 ppt | Not foundNot found in any of 14 samples, below 4 ppt |
| HFPO-DA (GenX) | 10 ppt | Not foundNot found in any of 14 samples, below 5 ppt |
| PFBS | Index only | Not foundNot found in any of 14 samples, below 3 ppt |
| Hazard IndexPFHxS, PFNA, HFPO-DA and PFBS together | 1 | Doesn’t applyDoesn’t apply: no sampling location found two or more of the four |
| Results from EPA’s UCMR 5 sampling. “Below” is the lab’s reporting level: a result under it reads as not found, which is not the same as zero. The limits are EPA’s 2024 rule, with compliance due from 2029; EPA has since proposed changes to some of them, explained on each compound’s page. PFBS has no limit of its own and counts only toward the Hazard Index, which adds up the four, each against EPA’s health-based level, from each sampling location’s average, as EPA’s UCMR 5 summary does. It counts only where two or more of the four were found, and is above the limit from 1.5. | ||
Above EPA’s health benchmark1
Lithium
Comes from the source
17.3ppb
Highest sample, April 21, 2025; found in 14 of 14
The highest sample was 17.3 ppb, above EPA’s health reference level of 10 ppb. That is a screening level, not an enforceable limit.
What handles it
No certification claim covers this compound yet.
Below EPA’s limits3
Fluoride
Forms or is added in treatment
0.34ppm
Highest yearly average, 2013 to 2019
2019 average: 0.28 ppm
Averaged by year, the highest was 0.34 ppm, in 2016, below EPA’s legal limit of 4.0 ppm. Its highest single sample was 0.37 ppm. In 2019, the latest year on file, its four samples averaged 0.28 ppm.
What handles it
- NSF/ANSI 58 look for “Fluoride Reduction”
- NSF/ANSI 53 look for “Fluoride”
Haloacetic acids (HAA5)
Forms or is added in treatment
1.9ppb
Highest yearly average, 2020 to 2022
2022 average: 1.7 ppb
Averaged by year, the highest was 1.9 ppb, in 2020, below EPA’s legal limit of 60 ppb. In 2022, the latest year on file, it averaged 1.7 ppb. Earlier, from 2012 to 2019, EPA’s file shows a highest yearly average of 8.0 ppb, in 2015.
What handles it
No certification claim covers this compound yet.
Total trihalomethanes (TTHM)
Forms or is added in treatment
1.6ppb
Highest yearly average, 2020 to 2022
Averaged by year, the highest was 1.6 ppb, in 2022, below EPA’s legal limit of 80 ppb. That was also the latest year on file. Earlier, from 2012 to 2019, EPA’s file shows a highest yearly average of 14.7 ppb, in 2015.
What handles it
- NSF/ANSI 53 look for “Trihalomethanes (TTHM) Reduction”
- NSF/ANSI 58 look for “Trihalomethanes (TTHM) Reduction”
34 compounds tested and not foundIncluding all six PFAS in EPA’s 2024 rule. Below the reporting level in every sample. Not found is not the same as zero.
From routine monitoring
- Arsenic
- Chromium (total)
- Lead
- Nitrate
- Uranium
PFAS and lithium, from EPA’s UCMR 5 sampling
- 11Cl-PF3OUdS
- 4:2 FTS
- 6:2 FTS
- 8:2 FTS
- 9Cl-PF3ONS
- ADONA
- HFPO-DA (GenX)
- NEtFOSAA
- NFDHA
- NMeFOSAA
- PFBA
- PFBS
- PFDA
- PFDoA
- PFEESA
- PFHpA
- PFHpS
- PFHxA
- PFHxS
- PFMBA
- PFMPA
- PFNA
- PFOA
- PFOS
- PFPeA
- PFPeS
- PFTA
- PFTrDA
- PFUnA
Disinfectant
City of Slidell Water Supply reported adding chloramine before water enters its pipes, at all 7 of its sampling points, in its 2024 to 2025 sampling for EPA.
Chloramine is chlorine combined with ammonia. It lasts longer in the pipes, and unlike chlorine, it doesn’t leave water that sits out. A filter’s chlorine claim doesn’t cover it: look for the separate chloramine claim under NSF/ANSI 42. No shower filter can carry one: NSF/ANSI 177, the shower filter standard, covers free chlorine only. Fish, turtles and frogs need it removed from their water. This is what the utility reported for that sampling. Its annual water quality report says what it uses now.
Violations since 2016
| Contaminant or rule | Type | Period | Measured | Status |
|---|---|---|---|---|
| Revised Total Coliform Rule | E. coli was confirmed in the water system.EPA: Maximum Contaminant Level Violation, E. coli (RTCR) | Sept. 1, 2022 to Sept. 30, 2022 | — | Resolved |
| Health-based violations only. Resolved and archived mean the utility returned to compliance or the state closed the record. | ||||
What this report can’t tell you
Everything else. Haloacetic acids (HAA5), total trihalomethanes (TTHM) and nitrate results here are Louisiana’s yearly averages as CDC publishes them, from 2020 on, with EPA’s national file for 2012 to 2019. Fluoride, arsenic, chromium (total) and uranium come from EPA’s file alone, which ends in 2019. City of Slidell Water Supply’s own annual report, which it must send you every year, has newer results for those and the contaminants this page does not show.
Your own plumbing. Lead results are the 90th percentile across homes the utility samples. Your home’s service line, solder and fixtures decide yours. A certified lab test is the only way to know.
What it means for your health. This page reports what the records show and EPA’s limits and goals; it is not medical advice. If you are worried about a health effect, talk to a doctor or your local health department.
Anything after the latest data. SDWIS data is from 2026 Q3; UCMR 5 samples are from Oct. 16, 2024 to April 21, 2025; CDC’s yearly averages for Louisiana cover 2020 to 2022; EPA’s compliance samples are from Sept. 10, 2013 to July 9, 2019.
Testing your own tap
The 3 labs Louisiana certifies closest to the area City of Slidell Water Supply serves, in a straight line. Call first: certification is test by test, and not every lab takes samples from homeowners.
Water Test, Inc.
Covington, LA · about 25 miles
Certified for bacteria
Curtis Environmental Services, Inc.
LaPlace, LA · about 40 miles
Certified for minerals and other inorganics, disinfection byproducts
LDH Amite Regional Laboratory
Amite, LA · about 53 miles
Certified for bacteria
Sources
- EPA UCMR 5 occurrence data, file of Oct. 15, 2026
- EPA SDWA bulk download (SDWIS federal data), 2026 Q3
- CDC Environmental Public Health Tracking Network, yearly averages Louisiana supplied to CDC, 2020 to 2022, read Oct. 8, 2026. TapBuff’s comparisons with EPA’s limits are its own, not CDC’s or Louisiana’s.
- EPA Six-Year Review 4 compliance monitoring data, 2012 to 2019, file of Feb. 5, 2024
- Disinfectant: EPA UCMR 5 occurrence data, additional data elements, file of Oct. 15, 2026
- Certified labs: LDH, laboratories certified by Louisiana for drinking water analysis, read Oct. 16, 2026; distances from the Census 2020 ZIP code tabulation area gazetteer
- Limits and goals: each contaminant’s page, with its EPA source.
- How this page is built: methodology.
PWSID LA1103041. Rebuilt from EPA data on Oct. 18, 2026.
Towns it serves
Also in St. Tammany Parish
- St Tam Parish - Bedico - Faubourg - Coquille18,372
- St Tam Parish - Briarwood Terrace17,536
- City of Covington Water Supply16,185
- City of Mandeville Water Supply13,000
- Utilities Inc - North Park Water Supply11,298
- Bayou Liberty Water Association10,791
What to do next
- Read up on LithiumWhat each one does to health, where it comes from, and the certification claim that addresses it.About Lithium
- Get the utility’s own reportCity of Slidell Water Supply must send you a water quality report every year. It covers contaminants this page does not show, and has newer results than EPA’s national file for the ones here that come from it.How to read it
- Test your own tap for leadYour service line, solder and fixtures decide the lead at your faucet, not the utility’s average.Lead in your water: what to do
- Decide if you want a filter at allA filter for taste or chlorine is a preference, not a need. The standards say what each kind can do.NSF/ANSI standards, decoded