Holbrook Water Hardness & Quality Report (2026)
Water Hardness
~120–179 mg/L
Hardestimated · not lab-verified
Source
reservoir
pH Level
8.2
neutral = 7.0
Lead
0.008 mg/L
✓ Below action level
TDS
427.3 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 Holbrook, your appliances are currently losing 20% efficiency due to mineral buildup.
| Appliance | In Holbrook | 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 Holbrook compares to its nearest neighbours
| City | Hardness | PFAS (ppt) | Risk | Source |
|---|---|---|---|---|
| ▶ Holbrook, New York | ≈ 120–179 mg/L | 8 ppt | 🟠 Hard | reservoir |
| Holtsville, New York | ≈ 120–179 mg/L | 8.3 ppt | 🟠 Hard | reservoir |
| Centereach, New York | ≈ 120–179 mg/L | 5.4 ppt | 🟠 Hard | reservoir |
| Farmingville, New York | ≈ 120–179 mg/L | 4.9 ppt | 🟠 Hard | reservoir |
| Lake Grove, New York | ≈ 120–179 mg/L | 8.4 ppt | 🟠 Hard | reservoir |
National Benchmark
How Holbrook compares to the USA average
| Benchmark | Hardness | Appliance Risk |
|---|---|---|
| ▶ Holbrook | ≈ 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 Holbrook's Water Unique?
Local geology and source profile
Holbrook, NY is served by the Suffolk County Water Authority (SCWA), the largest nonprofit water supplier in the United States, providing drinking water to over 1.2 million residents across Suffolk County on Long Island. The utility sources water exclusively from 57 active production wells tapping local groundwater aquifers, including those beneath Holbrook in the Town of Brookhaven. Water is drawn from the Upper Glacial and Magothy aquifers and treated at wellhead facilities for disinfection and corrosion control before distribution through an extensive pipeline network serving residential, commercial, and industrial customers.
Holbrook's groundwater recharge area spans central Suffolk County, encompassing the Ronkonkoma Moraine and Hempstead Plains, where precipitation infiltrates sandy glacial outwash and moraine deposits. Key geological features include the Quaternary Jameco Gravel and Upper Glacial aquifer underlain by the Pleistocene Magothy Formation, a thick sand aquifer with clay lenses overlying the Raritan Clay confining layer. Dissolution of carbonates from limestone fragments in glacial deposits and magnesium-bearing silicates in sandy strata imparts a moderately mineralised character, producing naturally harder groundwater than upstate surface supplies.
At moderately hard levels, Holbrook's water promotes limescale buildup in pipes, water heaters, and dishwashers, reducing efficiency and lifespan — expect 20–30% higher energy use in affected appliances. Kettles and faucets show white deposits quickest, and laundry may feel stiff without extra detergent. Maintenance involves monthly vinegar descaling for fixtures and annual heater flushes. A water softener is recommended for households noticing spots on glassware or film on skin after bathing. SCWA maintains EPA compliance with pH adjusted to 7.5–8.5 using sodium hydroxide; PFAS levels remain mostly below 10 ppt, well within New York's limits, with ongoing monitoring due to Long Island's industrial history.
Geology & Source: Suffolk County Long Island — Upper Glacial and Magothy aquifers; Quaternary glacial sand and gravel over Cretaceous Magothy Formation; limestone and dolomite in glacial till yield moderate hardness from carbonate dissolution
Other New York Water Reports
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Frequently Asked Questions
Is Holbrook's water safe to drink?
Do I need a water softener in Holbrook?
How does Holbrook compare to the USA average?
Data Sources & Methodology
Water quality data for Holbrook 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.