Delaware, Ohio Water Quality Report
Hardness levels, common contaminants, and what Delaware homeowners should know about their tap water — updated August 2026.
Delaware Water at a Glance
Water Hardness Meter — Delaware
At 13 grains per gallon, Delaware water is classified as Very Hard. Delaware County's limestone geology makes it one of the hardest water areas in Central Ohio.
Common Water Problems in Delaware
Delaware County sits on limestone bedrock, which naturally dissolves into groundwater. At 18 gpg, Delaware water is among the hardest in Central Ohio.
Delaware's water sources contain moderate iron levels. Homeowners on city water may notice slight orange staining on fixtures or laundry, particularly in older homes.
Delaware's higher total dissolved solids give tap water a noticeably mineral taste. Many residents use RO systems for drinking and cooking.
At 18 gpg, scale accumulates rapidly inside water heaters. A water heater in Delaware without a softener can lose significant efficiency within 2–3 years.
Recommended Treatment for Delaware Water
Based on typical Delaware water chemistry, these systems address the most common issues.
Essential for Delaware's 18 gpg water. Prevents scale damage and dramatically improves water quality throughout the home.
Addresses Delaware's moderate iron levels to prevent staining on fixtures and laundry.
Reduces TDS and improves drinking water taste — especially beneficial with Delaware's higher mineral content.
Iron Level: 0.1–0.25 mg/L
Delaware's water sources contain moderate iron (0.1–0.25 mg/L). If you notice orange staining on fixtures or laundry, a dedicated iron filter installed before the softener is the recommended solution.
Iron filter optionsDelaware Water FAQs
How hard is Delaware, Ohio water?
Delaware city water tests at approximately 18 grains per gallon (gpg), or about 308 mg/L. This is classified as very hard, driven by the area's limestone geology.
Why is Delaware County water so hard?
Delaware County sits on limestone and dolomite bedrock. As groundwater moves through these formations, it dissolves calcium and magnesium carbonate — the minerals that cause hardness. This is a natural geological characteristic of the region.
Does Delaware city water have iron?
Delaware's water sources contain moderate iron levels (typically 0.1–0.25 mg/L). While below the EPA secondary standard of 0.3 mg/L, some homeowners notice slight orange staining on fixtures or laundry. A free water test will confirm your home's iron level.
What water treatment is most common in Delaware, Ohio?
Most Delaware homeowners benefit from a water softener as the foundation, often combined with an iron filter if staining is present and an under-sink RO system for drinking water. A free in-home water test helps determine exactly what your home needs.
Know exactly what's in your Delaware water.
Our free in-home water test gives you precise numbers — hardness, iron, pH, TDS, chlorine — at your tap. No obligation, no pressure.