El Dorado Water Hardness & Quality Report (2026)
Water Hardness
15.1 grains per gallon
Source
river
pH Level
8.5
neutral = 7.0
Lead
0.009 mg/L
✓ Below action level
TDS
696.3 mg/L
Est. Daily Cost
$0.69
energy & soap waste
Source: USGS Water Quality Portal · Updated 2026
0–60
mg/L
Soft
61–120
mg/L
Moderately Hard
121–180
mg/L
Hard
180+
mg/L
Very Hard
Appliance Damage Report
In El Dorado, your appliances are currently losing 34% efficiency due to mineral buildup.
| Appliance | In El Dorado | Soft Water City | Efficiency Loss |
|---|---|---|---|
| Kettle | 1.5 yrs | 8.5 yrs | -82% |
| Washing Machine | 4 yrs | 12 yrs | -67% |
| Water Heater | 5.3 yrs | 15 yrs | -65% |
Regional Water Comparison
How El Dorado compares to its nearest neighbours
| City | Hardness | PFAS (ppt) | Risk | Source |
|---|---|---|---|---|
| ▶ El Dorado, Arkansas | 258.5 mg/L | 6.6 ppt | 🔴 Very Hard | river |
| Ruston, Louisiana | 165 mg/L | 13.9 ppt | 🟠 Hard | river |
| Minden, Louisiana | 130.5 mg/L | 11.6 ppt | 🟠 Hard | river |
| West Monroe, Louisiana | 100 mg/L | 9.6 ppt | 🟡 Moderately Hard | river |
| Monroe, Louisiana | 137.5 mg/L | 12.1 ppt | 🟠 Hard | river |
National Benchmark
How El Dorado compares to the USA average
| Benchmark | Hardness | Appliance Risk |
|---|---|---|
| ▶ El Dorado | 258.5 mg/L | 🔴 High |
| USA National Avg | 150 mg/L | 🟠 Moderate |
| Badger Top Rated | 8.5 mg/L | 🟢 None |
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What Makes El Dorado's Water Unique?
Local geology and source profile
El Dorado, Arkansas, in Union County — the Union County seat adjacent to Smackover in south Arkansas, a historic oil-boom city and the seat of the Arkansas oil industry (the El Dorado oil field was one of the largest early discoveries in the US), in the Gulf Coastal Plain of south Arkansas — receives its municipal water from the City of El Dorado Water Division, drawing from the Ouachita River or Smackover Creek reservoirs in Union County.
The very hard 258.5 mg/L hardness and high TDS of 696.3 mg/L reflect the Union County Gulf Coastal Plain's highly calcareous geology combined with possible oil-field brine influence in the local watershed. The Ouachita River at El Dorado drains both the Ouachita Mountains (Ordovician Bigfork Chert — insoluble) and the Gulf Coastal Plain — Cretaceous Nacatoch Sand (calcareous), Cretaceous Arkadelphia Marl (calcareous clay), and Eocene Wilcox Group (calcareous sand). The very high TDS may also reflect contributions from the historical Smackover Formation oil field brines (highly saline Jurassic carbonate) that have influenced the south Arkansas groundwater.
At 258.5 mg/L with TDS 696, El Dorado's water is very hard. A water softener is strongly recommended. Scale builds rapidly in all appliances and plumbing systems. The PFAS level of 6.6 ppt warrants a certified drinking water filter — the Pine Bluff Arsenal (Jefferson County AR — chemical weapons PFAS legacy in the Ouachita watershed), the El Dorado oil-refining corridor, and the south Arkansas PFAS background contribute to El Dorado's readings.
Geology & Source: El Dorado in Union County draws from the El Dorado Water Division on the Ouachita River (Union County) — the Ouachita drains the Gulf Coastal Plain (Cretaceous Nacatoch Sand, Eocene Wilcox calcareous) and the Ouachita Mountains (Ordovician Bigfork Chert) — Arkansas Gulf Coastal Plain Cretaceous-Eocene calcareous drainage produces very hard water at 258.5 mg/L with high TDS 696 mg/L in this Union County Arkansas city.