Louisville Water rates its Ohio River supply as moderately hard. Here is what that number means at the shower door and kitchen tap, which utility covers which suburb, and how to clean mineral film without damaging finishes.
Most Louisville homeowners know the look: a cloudy shower door a week after it was cleaned, a crusty ring at the base of the faucet, white spots on the dark dishes. That is calcium and magnesium from the tap, left behind when water evaporates.
Louisville's water is not among the hardest in the country, but it is hard enough to show. This guide explains the numbers from the utility's own report and how to keep up with them.
Louisville Water's 2025 Water Quality Report lists an average hardness of about 128 milligrams per liter across its two treatment plants, roughly 7.5 grains per gallon. The utility calls that moderately hard. Broken down, the water carries around 31 milligrams per liter of calcium and 13 of magnesium, with about 225 milligrams per liter of total dissolved solids and a pH near 8.6.
The source is the Ohio River. The Crescent Hill plant treats river water directly, and the B.E. Payne plant in Prospect treats groundwater drawn through riverbank filtration, where river water soaks through sand and gravel before it reaches the wells. The hardness figure in the report is the average across both plants.
Louisville Water's lines reach well past the city. The utility supplies Louisville Metro and parts of Bullitt, Hardin, Nelson, Oldham, Shelby and Spencer counties, pumping an average of 138 million gallons a day to nearly one million people. Many homes in the suburbs east of the city drink the same water as downtown.
Not all of them, though. The Oldham County Water District, based in La Grange, treats its own groundwater from wells drilled into the Ohio River alluvial aquifer. If you live in Oldham County, check your bill to see which utility you have, and look up that utility's report for its hardness figure.
Mineral film builds wherever water sits and dries. In a Louisville home, that is usually the same handful of places.
A squeegee after every shower does more than any product. Water that does not sit on the glass cannot leave minerals behind. For buildup that is already there, a diluted white vinegar solution or a cleaner made for mineral deposits works on glass and most chrome, followed by a rinse and a dry cloth.
Be careful with natural stone. Marble, travertine and limestone counters or shower walls react to acid, so vinegar can etch them. Use a stone-safe cleaner and a soft cloth instead. On older brass or specialty finishes, test any product in a hidden spot first.
The water also carries a chloramine residual. Louisville Water disinfects with chlorine and adds ammonia to keep it stable, so do not mix bleach-based cleaners with ammonia products, and rinse surfaces well between products.
A Recurring House Clean wipes down glass, sinks, tubs and fixtures each visit, which keeps new film from building. A One-Time Deep Clean goes further: shower glass is treated for hard water spots and faucets are detailed around the handles and aerators. Glass that years of minerals have etched can stay cloudy even when clean, and no cleaning can reverse that.
Older homes have one more water question. Louisville Water notes that homes built before about 1950 may still have a lead or galvanized private service line, and it replaces those for free through its Find and Fix program. That is a plumbing matter rather than a cleaning one, but it is worth a call if your house is that old. See the older home guide for more.
The questions Louisville homeowners ask most often about this topic, answered plainly.
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