Guide
Water hardness by town in PA, NJ & DE
Hardness in mg/L and grains per gallon from utility water quality reports for Philadelphia, Wilmington, Newark, Cherry Hill, Royersford & more.
Hardness is calcium and magnesium dissolved in water. Utilities report it in mg/L (or ppm) as calcium carbonate; softeners are sized in grains per gallon (gpg). One gpg equals 17.1 mg/L. The USGS calls 0–60 mg/L soft, 61–120 moderately hard, 121–180 hard, and above 180 very hard[1].
Hardness reported by local utilities
| Area | Utility | mg/L | gpg |
|---|---|---|---|
| Philadelphia (Baxter plant) | Philadelphia Water Department[2] | 98 (2024 avg.) | ≈5.7 |
| Philadelphia (Belmont plant) | Philadelphia Water Department[2] | 152 (2024 avg.) | ≈8.9 |
| Philadelphia (Queen Lane plant) | Philadelphia Water Department[2] | 168 (2024 avg.) | ≈9.8 |
| Royersford & nearby Montgomery County | Pennsylvania American Water, Royersford system[3] | 136 (2023 report) | 7.95 |
| Norristown | Pennsylvania American Water, Norristown system (at its entry point to the Royersford system)[3] | 139 (2023 report) | 8.13 |
| Wilmington, DE (Brandywine plant) | City of Wilmington[4] | 136 avg., 94–190 (2025 report) | ≈8.0 |
| Wilmington, DE (Porter plant) | City of Wilmington[4] | 154 avg., 100–228 (2025 report) | ≈9.0 |
| Newark, DE | City of Newark[5] | 68 (2025 report) | ≈4.0 |
| Bear, Hockessin, Middletown & other Artesian areas | Artesian Water Company[6] | 113 avg., 26–359 (2023 data, 2025 report) | ≈6.6 (1.5–21) |
| Cherry Hill, Voorhees & other Western system areas | New Jersey American Water, Western system[7] | 128 (2025 report) | 7.48 |
| Princeton & other Raritan system areas | New Jersey American Water, Raritan system[8] | — | 5–13 |
gpg values marked ≈ are our conversion from the utility's mg/L figure. Utilities update these numbers every year in their Consumer Confidence Report[9]; check yours for the latest. Aqua Pennsylvania areas such as King of Prussia and Media aren't in this table yet; check Aqua's latest report, or we'll measure hardness at your tap.
What the numbers mean at home
- Under about 3.5 gpg (60 mg/L): soft. A softener usually isn't needed.
- 3.5–7 gpg: moderately hard. You'll see some spotting; a softener is a comfort choice.
- 7–10.5 gpg (120–180 mg/L): hard. Scale builds in water heaters and on fixtures; most households here benefit from a softener.
- Above 10.5 gpg: very hard. Size the softener carefully and check for iron, which uses up capacity.
Private wells
Well water hardness varies from house to house. Ask your lab to include hardness and iron, or book our free in-home test.
Next steps
More guides
Common questions
How do I convert mg/L to grains per gallon?
Divide by 17.1. For example, 128 mg/L is about 7.5 grains per gallon.
Is hard water unsafe to drink?
No. Hardness isn't a health hazard and EPA sets no limit for it. It causes scale, spotting, and poor soap lather.
Why does my utility report a range?
Many utilities blend water from several sources or plants, so hardness changes by area and season. Artesian Water, for example, reports 26 to 359 ppm.
Clean water starts with knowing what's in it.
Sources
- USGS Water Science School: Hardness of water. www.usgs.gov/special-topics/water-science-school/science/hardness-water
- Philadelphia Water Department: 2024 Water Quality Report (PDF). water.phila.gov/wp-content/uploads/files/2024-pwd-water-quality-report.pdf
- Pennsylvania American Water: Royersford system (PWS ID 1150166) 2023 Annual Water Quality Report. www.amwater.com/ccr/royersford.pdf
- City of Wilmington, DE: 2025 Water Quality Report. ccrwilmingtonde.com/2025_City_of_Wilmington_Water_Quality_Report.pdf
- City of Newark, DE: 2025 Annual Water Quality Report. newarkde.gov/ccr
- Artesian Water Company (PWSID DE0000552): Water Quality Report for 2025. www.artesianwater.com/wp-content/uploads/wqawc2025-1.pdf
- New Jersey American Water: Western System (PWS ID NJ0327001) 2025 Annual Water Quality Report. amwater.com/njaw/resources/PDF/ccr/delaware_2025.pdf
- NJ American Water: Raritan/Hunterdon/Mercer/Somerset typical water quality (PDF). amwater.com/njaw/resources/raritanhunterdonmercersomerset_twq.pdf
- U.S. EPA: Consumer Confidence Reports (CCR) information for consumers. www.epa.gov/ccr/ccr-information-consumers
EPA records retrieved Oct 2026 from the EPA SDWIS and UCMR 5 public datasets. Utility records describe a water system, not the tap in your home. Records can lag and may be incomplete.