What is Wilmington water hardness in grains per gallon?

Wilmington's water hardness is 1.3 grains per gallon (GPG), equivalent to 22 parts per million (PPM). 1 GPG = 17.1 PPM.

Water Quality in Wilmington, DE

Wilmington's water has PFAS above EPA limits (6 ppt). An activated carbon filter can reduce PFAS levels. Read below for a full breakdown.

City of Wilmington · Source: Brandywine Creek · Serves 70,898 residents

Hardness (PPM)

TDS (PPM)

1.2

Chlorine (mg/L)

PFAS (ppt)

Lead (ppb)

Hardness Scale: Where Wilmington Falls

Soft 060120180250400+

Soft water

Wilmington's water comes from protected surface sources typical of the Northeast. At 22 PPM, the water is relatively soft. The primary concern in older northeastern cities is lead from aging plumbing infrastructure, particularly in buildings constructed before 1986.

What Wilmington's Water Means for Your Home

Wilmington's water is slightly hard at 22 PPM. At this level, hard water is not a significant concern for most households. Scale buildup is minimal, and a water softener would provide little measurable benefit. If you are considering water treatment in Wilmington, focus on contaminant filtration rather than softening.

PFAS contamination is a significant concern in Wilmington. At 6 parts per trillion, levels exceed the EPA's 2024 maximum contaminant level of 4 ppt. PFAS are synthetic chemicals that do not break down in the environment or the human body, which is why they are called "forever chemicals." Long-term exposure has been associated with increased cancer risk, thyroid disruption, and immune system effects. A whole-house activated carbon filter or point-of-use reverse osmosis system can reduce PFAS to safe levels. Look for NSF P473 certification when comparing products.

Contaminant	Detected	Health Guideline	Legal Limit	Status
Hardness (as CaCO₃)	22 PPM	< 60 PPM	No federal limit	✓ OK
Total Dissolved Solids	62 PPM	< 300 PPM	500 PPM	✓ OK
PFAS (total)	6 ppt	4 ppt (EPA)	4 ppt (2024)	⚠ Above limit
Lead	4 ppb	0 ppb (no safe level)	15 ppb (action level)	✓ Low
Chlorine / Chloramine	1.2 mg/L	Taste threshold ~1.0	4.0 mg/L	✓ Normal
Nitrate	1 mg/L	5 mg/L	10 mg/L	✓ OK

Recommendations for Wilmington Homes

🔬 Activated Carbon Filter for PFAS

PFAS detected at 6 ppt, above the EPA maximum contaminant level of 4 ppt. PFAS are linked to cancer, thyroid disease, and immune system effects with long-term exposure. A whole-house granular activated carbon (GAC) filter or a point-of-use reverse osmosis system can reduce PFAS. Look for NSF P473 certification, which specifically tests for PFAS removal.

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About Wilmington's Water Supply

Water Utility: City of Wilmington

Water Source: Brandywine Creek

Population Served: 70,898

Hardness: 22 PPM (1.3 grains per gallon)

Water quality can vary by neighborhood and season. The values above represent typical averages reported by City of Wilmington. To get exact numbers for your address, request a copy of the most recent Consumer Confidence Report (CCR) from your utility, or have your water independently tested.

Compare Wilmington to Other Delaware Cities

Dover

52 PPM · Slightly Hard

Frequently Asked Questions About Wilmington Water

Is Wilmington tap water safe to drink?

Wilmington's water meets EPA legal standards for drinking water safety. However, legal limits and health-optimal levels are different things. PFAS levels exceed the 2024 EPA health standard, which is a concern for long-term exposure. Review the contaminant table above for specific numbers and how they compare to both legal limits and health guidelines.

Do I need a water softener in Wilmington?

No. At 22 PPM, Wilmington's water is very soft. A water softener would provide no benefit here. Focus on filtration if you have specific contaminant concerns.

What water filter is best for Wilmington?

The best filter depends on which contaminants you want to address. For PFAS, look for a filter with NSF P473 certification. Granular activated carbon (GAC) and reverse osmosis systems are both effective. Standard carbon pitcher filters may not remove PFAS adequately. See our softener vs. filter guide to understand the difference between these categories.

Where does Wilmington's water come from?

Wilmington's drinking water is sourced from Brandywine Creek and treated by City of Wilmington. Wilmington's water comes from protected surface sources typical of the Northeast. At 22 PPM, the water is relatively soft.

What is the hardness of Wilmington water in grains per gallon?

Wilmington's water hardness is 1.3 grains per gallon (GPG), which equals 22 parts per million (PPM). This is classified as slightly hard. To convert: 1 GPG = 17.1 PPM.

Does Wilmington water damage tankless water heaters?

At 1.3 GPG, Wilmington's water is unlikely to cause significant issues for tankless water heaters. However, if you notice reduced flow or efficiency over time, scale buildup could be a factor. Annual flushing with vinegar is good maintenance regardless of hardness.

Is Wilmington water safe for babies and infants?

Wilmington's water meets all EPA safety standards and is generally considered safe for preparing infant formula. The hardness minerals (calcium and magnesium) are not harmful. If your home has older plumbing, running cold water for 30 seconds before use is a good precaution to flush any lead from pipes.

Data sources. Water quality data compiled from EPA SDWIS, EWG Tap Water Database, USGS water hardness studies, and the City of Wilmington Consumer Confidence Report. Hardness and contaminant levels represent typical average values and may vary by neighborhood and season. Last updated: 2026-02-12.