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Alabama water profile

Nitrate in Alabama community water systems

Alabama runs mostly low on nitrate, and the reason is depth: its big public supplies draw from deep Coastal Plain aquifers where USGS finds nutrients largely absent. The higher readings that do appear sit on shallower ground. See where the pattern concentrates and what each reporting system measured in the three years from August 9, 2023 to August 9, 2026.

Browse all 494 Alabama systems →

Search by the utility or system name shown on a water bill. Example: Huntsville Utilities. Private wells are not in this inventory.

99%
of the state’s 500 active community water systems have a current result here
494
systems with a current nitrate result
6,247,890
people served by those reporting systems
1.0%
of reporting systems at or above 5 mg/L
How to read these numbers Each system is placed into a band by its most recent reported result within a rolling three-year window. The bands describe how strongly human activity, read from nitrate, has marked a water source; they are not a safety verdict. Figures describe system reporting, not nitrate measured at an individual tap.

How Alabama's systems fall across the five bands

Most systems report below 3 mg/L

Natural background
0.00–0.99 mg/L as N
398 systems · 4,851,737 served
Human impact likely
1.00–2.99 mg/L as N
76 systems · 1,010,170 served
Human impact clear
3.00–4.99 mg/L as N
15 systems · 307,326 served
Health-study range
5.00–9.99 mg/L as N
5 systems · 78,657 served
Above the federal limit
10.00 mg/L and above
0 systems · 0 served

Each system appears in one band only, placed by its most recent reported result in the current three-year window. Counts sit beside people served so a small number of larger systems cannot hide behind a row of tiny ones. Of the 5 systems reporting 5 mg/L or more, 2 stayed at or above 5 across the whole three-year range; the other 3 reached it only on a high sample and otherwise ran lower.

Most recent reading Jun 2026; the typical system was last tested around Feb 2026. 351 systems sampled their own water; 143 systems carry a supplier’s result.

The named systems

Every reading here belongs to a utility with a name

Highest recent readings
SystemMost recent resultBandBased onPeople served
Perdido Bay Water Sewer & Fpd6.80 mg/LFeb 2026a high point — runs lowerHealth-study range15 samples12,765
Mexia Water System, Inc.5.73 mg/LMay 2026Health-study range12 samples2,532
Summerdale, Ww Board Of The Town Of5.09 mg/LMay 2026Health-study range12 samples1,800
Fairhope, City Of5.00 mg/LApr 2026a high point — runs lowerHealth-study range32 samples59,850
Leroy Water Authority5.00 mg/LApr 2026Health-study range27 samples1,710
Frisco City Water System4.30 mg/LFeb 2026Human impact clear6 samples2,100
West Escambia Utilities, Inc.4.20 mg/LApr 2026a high point — runs lowerHuman impact clear15 samples12,060
Madison County Water Department4.06 mg/LJan 2026Human impact clear3 samples119,100
Largest systems
SystemMost recent resultBandBased onPeople served
Central Alabama Water System0.49 mg/LAug 2025Natural background20 samples585,000
Huntsville Utilities Water Dept.0.11 mg/LMay 2026Natural background12 samples310,107
Mobile, Bd. Of W&S Comm. Of The City Of0.09 mg/LApr 2026Natural background9 samples279,000
Montgomery Ww&Ssb, City Of0.28 mg/LOct 2025Natural background18 samples276,000
Tuscaloosa Water & Sewer0.06 mg/LJan 2026Natural background7 samples166,524

Each result shows its date and what it rests on, so a lone sample is never taken for a settled measurement. A single high sample is not a complete account of what a household drinks.

Where higher nitrate concentrates

A light signal on shallow ground

Human impact is clear on drinking water served in nine of Alabama’s 67 counties. Each is shaded by how many of its systems reported 3.00 mg/L as N or above. Shading counts systems, not severity — a county with many small utilities can outrank one holding a single larger system that reads higher. The table beside the map splits the two bands so that difference stays visible.

AL counties shaded by number of community water systems reporting nitrate at or above 3.00 mg/L as NCounties are shaded by how many community water systems reported nitrate at or above 3.00 mg/L as N in the three years from August 9, 2023 to August 9, 2026. The same counts appear in the table below this map.Baldwin County — 2 systems at 3.00–4.99 mg/L as N; 3 systems at 5.00 mg/L as N or aboveSt. Clair County — 5 systems at 3.00–4.99 mg/L as N; 0 systems at 5.00 mg/L as N or aboveEtowah County — 1 system at 3.00–4.99 mg/L as N; 0 systems at 5.00 mg/L as N or aboveLimestone County — 1 system at 3.00–4.99 mg/L as N; 0 systems at 5.00 mg/L as N or aboveWashington County — 0 systems at 3.00–4.99 mg/L as N; 1 system at 5.00 mg/L as N or aboveBarbour County — 1 system at 3.00–4.99 mg/L as N; 0 systems at 5.00 mg/L as N or aboveMadison County — 2 systems at 3.00–4.99 mg/L as N; 0 systems at 5.00 mg/L as N or aboveMonroe County — 2 systems at 3.00–4.99 mg/L as N; 1 system at 5.00 mg/L as N or aboveEscambia County — 1 system at 3.00–4.99 mg/L as N; 0 systems at 5.00 mg/L as N or above
none1–23–56–1112–2526+Number of drinking water systems reporting ≥3.00 mg/L NO₃–N per county as of August 9, 2026

Baldwin leads this layer with 3 reporting systems, followed by Monroe, Washington. A light signal on shallow ground. Coverage note: the map places 96% of Alabama’s reporting systems. Of the rest, 7 carry a supplier’s result measured elsewhere and belong off this map; 11 sampled their own water and are missing a county in the records, so the map reads as a floor by at least that much.

Counties with the most systems at or above 3 mg/L as N
County3–4.99≥5Total ≥3
Baldwin235
St. Clair505
Monroe213
Madison202
Barbour101

Counts use each system's most recent reported result in the current three-year window. A system appears in only one of the two bands. Coverage note: the map places 96% of Alabama’s reporting systems. Of the rest, 7 carry a supplier’s result measured elsewhere and belong off this map; 11 sampled their own water and are missing a county in the records, so the map reads as a floor by at least that much.

Find a specific Alabama system

What the statewide pattern says

Deep aquifers protect; shallow farm ground shows

Alabama's higher nitrate is a shallow-aquifer story — the farmed limestone plateaus of the north and the sandy coastal aquifers of Baldwin County — while deep public-supply aquifers run clean.

The statewide baseline is protective. USGS sampling of the deep Coastal Plain aquifers that serve public supply — wells 250 to 2,000 feet deep — found nutrients were not present at high or even moderate concentrations anywhere in the study area (Barlow, 2016 — USGS Fact Sheet 2016-3076). Depth and confining clay do the work.

The shallow settings tell the other half. In the Interior Low Plateaus of north Alabama, where row crops have grown on limestone since the early 1800s, the Paleozoic carbonate aquifer carries a median nitrate of 1.3 mg/L — higher than every other Alabama aquifer's median — attributed to crop fertilization (USGS National Water Summary, Alabama). And in southern Baldwin County, study of the sandy coastal aquifers found the highest nitrate in the central and northeastern parts of the county, sourced primarily to agricultural inputs (Murgulet and Tick; see also KarimiDermani and others, 2025).

That split is the Alabama map: Baldwin County on the coast and a thin scatter through the northern farm counties — St. Clair, Madison, Monroe — mark the shallow, farmed, or karst-influenced ground, while the deep-aquifer cities stay quiet.

The supported source reading is agricultural nitrogen on shallow or karst ground — not a certified source at any individual system (Nolan and Hitt, 2006).

The general science — how nitrate moves, why some ground is vulnerable, and why the legacy lingers — is laid out with its sources on Where nitrate comes from.

Questions this page answers

What the Alabama pattern does—and does not—say

Where does nitrate concentrate in Alabama community water systems?

Baldwin leads this layer with 3 reporting systems, followed by Monroe, Washington. A light signal on shallow ground.

Why is most of Alabama quiet on nitrate?

Depth. The big public supplies draw from Coastal Plain aquifers hundreds to thousands of feet down, and USGS found nutrients absent at high or moderate levels across that entire depth zone. Alabama's nitrate appears where wells are shallow: the farmed limestone plateaus of the north and the sandy coastal aquifers of Baldwin County.

What is the Baldwin County setting?

Sandy, shallow, and farmed. Studies of southern Baldwin County's coastal aquifers found the highest nitrate in the county's central and northeastern areas, attributed primarily to agricultural inputs — the Weeks Bay farm belt of row crops and pasture over permeable sand.

Does a high public-system result mean a nearby private well is high?

No. It is a local sentinel, not a well-specific result. It shows that nitrogen and a transport pathway have reached groundwater in the area; a certified-lab test is still the only way to know a specific private well.

Sources and provenance

What this page rests on

  1. NitrateSmart inventory: 494 Alabama community water systems with a current nitrate result in the three years from August 9, 2023 to August 9, 2026. Figures count people served by reporting systems, not measured tap exposure.
  2. Nolan BT, Hitt KJ (2006). Vulnerability of Shallow Groundwater and Drinking-Water Wells to Nitrate in the United States. Environmental Science & Technology 40(24):7834–7840.
  3. Dubrovsky NM, and others (2010). Nutrients in the Nation's Streams and Groundwater, 1992–2004. USGS Circular 1350.
  4. Barlow JRB (2016). Groundwater Quality in the Southeastern Coastal Plain Aquifer System. USGS Fact Sheet 2016-3076 — nutrients not present at high or moderate concentrations at public-supply depth.
  5. USGS National Water Summary 1986 — Alabama. Ground-Water Quality summary — Paleozoic carbonate aquifer median nitrate 1.3 mg/L attributed to crop fertilization on the Interior Low Plateaus; highest of Alabama aquifers.
  6. KarimiDermani B, and others (2025). Analyzing multi-year nitrate concentration evolution in Alabama aquatic systems. Environments 12(3):75 — reviews Murgulet and Tick’s southern Baldwin County finding of agriculturally sourced aquifer nitrate.