London, Ohio Water Quality Report
Hardness levels, common contaminants, and what London homeowners should know about their tap water — updated August 2026.
London Water at a Glance
Water Hardness Meter — London
At 16 grains per gallon, London water is classified as Very Hard. For context, anything above 10.5 gpg is considered hard; Columbus-area water typically runs 15–18 gpg.
Common Water Problems in London
London water at 16 gpg causes significant scale buildup on water heaters, dishwashers, and plumbing. Madison County's limestone geology is the primary source of the calcium and magnesium that drive hardness.
Madison County is one of Ohio's most productive farming counties. Nitrates and herbicide residues from agricultural runoff can enter London's water supply. An RO system provides critical protection for drinking water.
London area water can carry iron levels at or near the EPA secondary standard of 0.3 mg/L. Some homeowners notice orange or rust-colored staining on sinks, toilets, and laundry.
At 16 gpg, London water reacts with soap to form a sticky residue that leaves spots on dishes, glass shower doors, and fixtures. Homeowners frequently report cloudy glassware and difficult-to-clean bathroom surfaces.
Recommended Treatment for London Water
Based on typical London water chemistry, these systems address the most common issues.
Addresses London's 16 gpg hardness, protects appliances and plumbing, and eliminates soap scum and spotting.
Removes nitrates and agricultural contaminants — important for Madison County's farming-intensive watershed.
Recommended for London homes with orange staining. Removes iron before it reaches the softener, extending resin life.
Iron Level: 0.1–0.3 mg/L
Iron above 0.3 mg/L causes orange staining on fixtures, laundry, and appliances. The EPA secondary standard is 0.3 mg/L. If you notice rust-colored stains or metallic taste, a dedicated iron filter may be needed alongside a water softener.
Iron filter optionsLondon Water FAQs
How hard is London, Ohio water?
London water tests at approximately 16 grains per gallon (gpg), or about 274 mg/L. This is classified as very hard. Madison County sits on limestone-rich geology that naturally elevates hardness minerals in the water supply.
Does London, Ohio water have nitrates?
Madison County is one of Ohio's most intensively farmed counties, which increases the risk of nitrate contamination from agricultural runoff. London's water plant monitors nitrate levels, but an under-sink reverse osmosis system provides the most reliable protection for drinking water.
Is London, Ohio water safe to drink?
London water meets all EPA Safe Drinking Water Act standards. However, given Madison County's agricultural intensity and the high hardness level, most homeowners benefit from a water softener plus an RO system for drinking water.
What water treatment do London, Ohio homeowners need?
Most London homes benefit from a whole-home water softener to address the 16 gpg hardness, plus an under-sink reverse osmosis system for drinking water. Homes with visible iron staining should also consider an iron filter installed before the softener.
Know exactly what's in your London water.
Our free in-home water test gives you precise numbers — hardness, iron, pH, TDS, chlorine — at your tap. No obligation, no pressure.