Mount Prospect Water Hardness & Quality Report (2026)
Water Hardness
~120–179 mg/L
Hardestimated · not lab-verified
Source
river
pH Level
8.1
neutral = 7.0
Lead
0.004 mg/L
✓ Below action level
TDS
354 mg/L
Est. Daily Cost
$0.40
energy & soap waste
Source: See methodology section below · 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 Mount Prospect, your appliances are currently losing 20% efficiency due to mineral buildup.
| Appliance | In Mount Prospect | Soft Water City | Efficiency Loss |
|---|---|---|---|
| Kettle | 6.8 yrs | 8.5 yrs | -20% |
| Washing Machine | 9.6 yrs | 12 yrs | -20% |
| Water Heater | 12 yrs | 15 yrs | -20% |
Regional Water Comparison
How Mount Prospect compares to its nearest neighbours
| City | Hardness | PFAS (ppt) | Risk | Source |
|---|---|---|---|---|
| ▶ Mount Prospect, Illinois | ≈ 120–179 mg/L | 0 ppt | 🟠 Hard | river |
| Prospect Heights, Illinois | ≈ 120–179 mg/L | 9.3 ppt | 🟠 Hard | river |
| Arlington Heights, Illinois | ≈ 120–179 mg/L | 0 ppt | 🟠 Hard | river |
| Des Plaines, Illinois | ≈ 120–179 mg/L | 0 ppt | 🟠 Hard | river |
| Elk Grove Village, Illinois | ≈ 120–179 mg/L | 0 ppt | 🟠 Hard | river |
National Benchmark
How Mount Prospect compares to the USA average
| Benchmark | Hardness | Appliance Risk |
|---|---|---|
| ▶ Mount Prospect | ≈ 120–179 mg/L | 🟠 Moderate |
| USA National Avg | 151 mg/L | 🟠 Moderate |
| Scarsdale Top Rated | 0.02 mg/L | 🟢 None |
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What Makes Mount Prospect's Water Unique?
Local geology and source profile
Mount Prospect Water Department serves over 56,000 residents in Mount Prospect, Illinois, within Cook County, northwest of Chicago. The utility sources water mainly from Lake Michigan via the Chicago region's intake cribs and distribution system, supplemented by groundwater wells tapping local aquifers. Water is treated at regional facilities including the Jardine Water Purification Plant before local distribution; no dedicated on-site treatment plant is operated. The village covers approximately 10 square miles in the service area.
The supply originates from the Lake Michigan watershed, North America's largest freshwater system by surface area, shaped by glacial scouring that limits mineral dissolution. Blended groundwater interacts with glacial drift over Ordovician and Silurian carbonate bedrock, including dolomite and limestone layers from ancient shallow seas — specifically the Galena-Platteville Group and Niagaran dolomites. This geology imparts a hard character through natural leaching of alkaline earth metals, contrasting the lake's softer baseline and resulting in moderately mineralised water overall.
Hard water promotes scale accumulation in pipes, heaters, and fixtures, shortening lifespan of water heaters, dishwashers, and washing machines while boosting energy costs by up to 20–30%. Soap efficiency drops, leaving residue on dishes and causing skin dryness. Routine flushing of water heaters, vinegar descaling of faucets, and installing a whole-house softener are recommended to mitigate buildup and extend appliance life. The water meets all applicable EPA standards, with pH maintained around 7.5–8.5 and corrosion control implemented for lead and copper compliance.
Geology & Source: Lake Michigan glacial surface water blended with groundwater from glacial drift aquifers; Ordovician Galena-Platteville Group dolomites and Silurian Niagaran dolomites dissolve calcium and magnesium, elevating hardness above the lake baseline
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Frequently Asked Questions
Is Mount Prospect's water safe to drink?
Do I need a water softener in Mount Prospect?
How does Mount Prospect compare to the USA average?
Data Sources & Methodology
Water quality data for Mount Prospect is derived from geographic and geological modelling of the surrounding region. No federal monitoring station data was available for this location.
Water Hardness
Modelled estimate based on state-level USGS geological survey data for this region. No direct USGS Water Quality Portal measurement was matched to this city — the value reflects a statistical range calibrated to the state's dominant rock types and typical source water characteristics.
pH
Estimated from regional geology and source water characteristics. pH is correlated with water hardness and local bedrock — values may differ from utility-reported figures.
TDS — Total Dissolved Solids
Estimated using a derived ratio from water hardness and regional conductance profiles. TDS in natural water correlates strongly with total mineral content including hardness ions.
PFAS — Perfluoroalkyl and Polyfluoroalkyl Substances
EPA UCMR5 (5th Unregulated Contaminant Monitoring Rule, 2023–2025) — sum of PFAS compounds detected at the public water system serving this city. A value of 0 indicates the system was sampled with no detection above reporting limits.
Lead
Modelled estimate based on the EPA Lead and Copper Rule 90th-percentile tap-sample methodology. No publicly available per-city lead dataset with sufficient national coverage exists. Values are a conservative baseline derived from city population tier and infrastructure age — all estimates are maintained below the EPA action level of 0.015 mg/L.
Appliance Lifespan
Calculated from water hardness using a linear degradation model. Baseline lifespans represent soft-water performance (kettle: 8.5 yrs, washing machine: 12.0 yrs, water heater: 15.0 yrs). Hard water mineral scale progressively reduces operational life in direct proportion to hardness concentration.