How does Portsmouth's water compare to the national average?

The USA national average is 151 mg/L. Portsmouth (≈ 120–179 mg/L) is 1 mg/L softer than average.

Portsmouth Water Hardness & Quality Report (2026)

Water Hardness

hard

~120–179 mg/L

Hard

estimated · not lab-verified

Source

reservoir

pH Level

7.7

neutral = 7.0

Lead

0.008 mg/L

✓ Below action level

TDS

174.6 mg/L

Est. Daily Cost

$0.40

energy & soap waste

Source: See methodology section below · Updated 2026

hard~120–179 mg/LHard · est.

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 Portsmouth, your appliances are currently losing 20% efficiency due to mineral buildup.

Appliance	In Portsmouth	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 Portsmouth compares to its nearest neighbours

City	Hardness	PFAS (ppt)	Risk	Source
▶ Portsmouth, Rhode Island	≈ 120–179 mg/L	0 ppt	🟠 Hard	reservoir
Middletown, Rhode Island	≈ 0–60 mg/L	7.6 ppt	🟢 Soft	groundwater
Bristol, Rhode Island	≈ 180+ mg/L	8.3 ppt	🔴 Very Hard	reservoir
Newport East, Rhode Island	≈ 0–60 mg/L	24.5 ppt	🟢 Soft	reservoir
Newport, Rhode Island	≈ 0–60 mg/L	24.5 ppt	🟢 Soft	reservoir

National Benchmark

How Portsmouth compares to the USA average

Benchmark	Hardness	Appliance Risk
▶ Portsmouth	≈ 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 Portsmouth's Water Unique?

Local geology and source profile

Source: ReservoirTDS: 174.6 mg/LpH: 7.7

Portsmouth Water & Fire District serves approximately 16,726 residents in Portsmouth, Rhode Island, on Aquidneck Island. The utility purchases treated surface water primarily from reservoirs managed by the Newport Water Division or regional suppliers. Water is distributed from the main facility at 1944 East Main Road, Portsmouth, RI 02871; contact (401) 683-2090 or info@portsmouthwater.org for service inquiries. The district covers Portsmouth and adjacent areas in Newport County, with no specific treatment plants named in available data. Annual Consumer Confidence Reports are available at portsmouthwater.org.

The supply originates in the Narragansett Bay watershed, encompassing local reservoirs on Aquidneck Island that state assessments flag as vulnerable to contamination. Underlying geology includes Providence Formation metamorphic rocks of Cambrian-Ordovician age and overlying unconsolidated glacial deposits from the Pleistocene Wisconsinan glaciation. These sedimentary and metamorphic rocks impart a moderately mineralised character to the surface water through natural dissolution of calcium and magnesium from limestone-influenced soils and fractured bedrock aquifers, resulting in a supply with notable but not extreme mineral content.

At moderately hard levels, scale buildup occurs in appliances like water heaters, dishwashers, and coffee makers, reducing efficiency and lifespan. Laundry may feel stiff, and soap lathering is less effective. Regular maintenance includes deliming fixtures annually, using vinegar soaks for showerheads, and installing scale inhibitors. A water softener is often recommended for households with hard water concerns. Portsmouth's supply shows 4 contaminants above EPA health guidelines, including total trihalomethanes (TTHMs), di-n-butyl phthalate, selenium, and potential PFAS; the utility provides full compliance details in its annual CCR. Treatment involves standard surface water processes: disinfection, coagulation, and filtration.

Geology & Source: Aquidneck Island, Narragansett Bay watershed; Providence Formation metamorphic bedrock (Cambrian-Ordovician) with Pleistocene Wisconsinan glacial deposits; calcium and magnesium leaching through limestone-influenced soils yields moderate hardness

Other Rhode Island Water Reports

Middletown

≈ 0–60 mg/L

🟢 Soft

Bristol

≈ 180+ mg/L

🔴 Very Hard

Newport East

≈ 0–60 mg/L

🟢 Soft

Newport

≈ 0–60 mg/L

🟢 Soft

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All reports are reviewed by our team. Thank you for supporting data quality!

Frequently Asked Questions

Is Portsmouth's water safe to drink?

Yes. Portsmouth's water meets all federal safety standards. The hardness is ≈ 120–179 mg/L (Hard), which is safe to drink. High hardness affects appliances and taste, but poses no health risk.

Do I need a water softener in Portsmouth?

At ≈ 120–179 mg/L (Hard), Portsmouth's water will cause significant limescale on kettles, washing machines, and water heaters. A water softener or descaler is strongly recommended to extend appliance lifespan and reduce energy bills by up to 20%.

How does Portsmouth compare to the USA average?

The USA national average is 151 mg/L. Portsmouth (≈ 120–179 mg/L) is 1 mg/L below the national average. The softest major city is Scarsdale at just 0.02 mg/L.

Data Sources & Methodology

Water quality data for Portsmouth is derived from geographic and geological modelling of the surrounding region. No federal monitoring station data was available for this location.

Estimated

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.

Estimated

Estimated from regional geology and source water characteristics. pH is correlated with water hardness and local bedrock — values may differ from utility-reported figures.

Estimated

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.

Measured

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.

Modelled

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.

Calculated

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.