Dearborn Water Is Moderate — Here's What It Costs You Each Year

Why Is Dearborn Water So Moderate?

Dearborn’s water sits at 5.94 GPG (101.5 ppm), which puts it just inside the “hard” category but well below the “very hard” threshold of 10.5 GPG. The reason comes down to where the water starts its journey. This is surface water, not groundwater. The city draws from the Great Lakes system, and that distinction matters more than most people realize.

Lake water doesn’t spend centuries soaking through limestone and dolomite the way well water does. It doesn’t have the same chance to pick up dissolved calcium and magnesium from deep rock formations. Instead, the water that reaches Dearborn is a mix of rainfall, snowmelt, and river inflow that has passed over the region’s glacial till and sedimentary bedrock relatively quickly. The Great Lakes basin is carved out of ancient Paleozoic rock, mostly shale, sandstone, and some limestone, but the water itself is in constant motion. That means less contact time with the minerals, and less hardness as a result.

You’re looking at roughly 101.5 parts per million of hardness, which is moderate by any standard. For comparison, the USGS classifies water above 7 GPG as hard and above 10.5 GPG as very hard. Dearborn doesn’t come close to those upper tiers. The national average is about 7.3 GPG, so this city actually runs a bit softer than the typical American home. That’s not an accident of treatment. It’s a function of the source. Surface water from the Great Lakes simply carries less dissolved mineral load than the deep aquifers that supply much of the Midwest.

What this means practically is that Dearborn residents deal with some scale buildup, but not the aggressive, crust-forming problems you’d see in, say, parts of Indiana or Illinois where wells punch into thick carbonate layers. You’ll notice film on glassware and maybe a bit of stiffness in laundry, but you won’t be chiseling scale off your showerhead every few months. The water is hard enough to matter, soft enough to live with. That’s the whole story.

How Dearborn Compares to Nearby Cities

Dearborn’s 5.94 GPG puts it in a fairly comfortable middle ground relative to its neighbors in southeast Michigan. Because the region relies heavily on the same Great Lakes surface water sources, most nearby communities see similar numbers. The water chemistry doesn’t change dramatically just because you cross a city line. What changes is the treatment approach and the age of the distribution pipes, not the underlying geology.

Cities drawing from the Detroit River and Lake St. Clair tend to report hardness in the same general range as Dearborn. You’re not going to see a dramatic jump from 6 GPG in Dearborn to 15 GPG in a neighboring suburb, because they’re all pulling from the same surface water system. That’s the advantage of the Great Lakes. The water is consistent, mineral-poor compared to groundwater, and relatively predictable year-round.

The differences you might notice between Dearborn and nearby towns come down to treatment, not source. Some municipalities blend in groundwater to meet demand during peak summer months, which can nudge hardness up temporarily. Others add corrosion control chemicals that don’t change hardness but do affect how the water feels and tastes. So if you’ve got a friend in a neighboring suburb who swears their water is softer or harder than yours, they might be right, but the gap is probably smaller than they think.

The USGS notes that roughly 85 percent of American households have hard water, and southeast Michigan is squarely in that camp. Dearborn just happens to be on the gentler end of the spectrum. You’re dealing with moderate hardness, not the extreme stuff. That means your water heater will lose some efficiency over time, but not at the catastrophic rate you’d see with very hard water. The Battelle Memorial Institute and WQRF found that gas water heaters lose about 4 percent efficiency per 5 GPG of hardness, and the DOE warns that a quarter inch of scale can cut efficiency by up to 40 percent. At 5.94 GPG, Dearborn homes will see scale accumulate, just more slowly than their counterparts in harder-water regions.

Fair enough, the water isn’t perfect. It’s hard enough that you’ll use more soap and detergent than you would with softened water. The WQA and Battelle found that soft water can cut laundry detergent use by up to 50 percent and dish soap by up to 70 percent. But compared to the rest of the country, and even compared to some of Michigan’s groundwater-dependent communities, Dearborn residents have it relatively easy.

How does Dearborn stack up against the rest of Michigan? It's moderate at 5.94 GPG — Grand Rapids, Ann Arbor, and Troy sit nearby with different numbers. See the full hardest-water ranking for context.

See where Dearborn sits on the Michigan water hardness map →

Want the broader explainer on what hardness actually is and how it behaves? Read hard water vs. soft water, explained.