Louisville's cast-iron Main Street facades send iron-stained runoff down the glass, and spring pollen peaks in the Derby-week window. Water: 128 mg/L.
Louisville's water sits just over the line into hard and runs alkaline, so a tap-water rinse will mark sunlit panes. Downtown's cast-iron facades shed iron-stained runoff, and spring pollen peaks around Derby week, when cleaning slots book up early. July to October is the steadiest window; a single-story exterior runs $300 to $550.
Louisville Water publishes 128 mg/L, seven and a half grains per gallon, which crosses just over the line into hard. The mineral load alone is manageable. What deserves more attention is the pH the same table reports, steady at 8.7 across both published years: that is alkaline enough to matter when an alkaline cleaner is diluted in it, because the water is adding to the pH rather than moderating it. On a hot elevation the practical consequence is a narrower window before a film sets rather than a heavier deposit.
| Hardness | 128 mg/L as CaCO₃ No band label published; 128 mg/L is HARD on the USGS ladder, just over the boundary. |
|---|---|
| pH | 8.6 |
| Alkalinity | 76 mg/L as CaCO₃ |
| Sodium | 26 mg/L |
| Chloride | 33 mg/L |
| Total dissolved solids | 225 mg/L |
| Disinfectant | chloramine |
| Source and treatment | Surface water, per the EPA SDWIS federal record · Powdered activated carbon and permanganate, pre pH adjustment, coagulation, flocculation, lime and soda ash softening with sedimentation and filtration, chlorination with chloramines as the residual, fluoridation and pH adjustment for corrosion control · The plant softens. |
Not in the report: corrosion index, iron and manganese.
SOURCE · Louisville Water 2025 Consumer Confidence Report, “Additional water quality data” box averaging Crescent Hill and B.E. Payne finished water, with the EPA SDWIS federal treatment record, PWS KY0560258 · How we source these numbers
Derby week in early May is the fixed point the rest of the year arranges itself around, and it lands in the middle of the Ohio Valley pollen season. Beyond that, the river corridor holds humidity on shaded elevations, and the cast-iron facades along Main Street shed rust-streaked runoff onto the glass below them every time it rains heavily.
KENTUCKY SEASON BY SEASON →Louisville Water treats Ohio River water and publishes a hardness of 128 mg/L, about seven and a half grains per gallon. Old Louisville's Victorian glazing is the conservation speciality and cast-iron facade runoff is the distinctive stain, needing rust chemistry rather than detergent. Derby week is the year's concentrated pricing window and it collides with pollen season.
Louisville Water Company publishes the figure in its own annual report, and its editions agree closely: 128 ppm, 7.5 grains per gallon, in the 2025 report, after 123 ppm and 135 ppm in two earlier years. The 2025 table gives alkalinity at 76 and a pH of 8.6, which is distinctly alkaline and the more useful of the two numbers for anyone choosing a cleaner.
Figures quoted online for Louisville are broadly right for once. A commonly quoted 7.2 grains per gallon is close to the utility's own figure, though it is often labelled moderately hard when it is hard on every standard scale.
That same source calls 7.2 grains per gallon 'moderately hard' when it is hard on every published ladder, including the one Tulsa's own utility prints. A customer quoting a band label rather than a number is often quoting a mistake.
Old Louisville holds the largest concentration of Victorian residential glazing in Kentucky and one of the most significant in the country. Leaded, stained and wavy single-pane glass in original sash is irreplaceable, and a blade or a wet came joint does damage that cannot be undone.
The cast-iron facades along Main Street are a rust problem rather than a dirt one. Heavy rain sheds iron-stained runoff down onto the glass below, and that mark needs a reducing or acid treatment rather than the detergent that handles ordinary grime.
Derby week in early May compresses residential and commercial demand into a single stretch across the Highlands, Crescent Hill and Old Louisville, booked well ahead at rates unrelated to the rest of the calendar. It also lands in the middle of the Ohio Valley pollen season, so timing matters as much as availability.
Derby week is the most concentrated pricing window in the market: residential and commercial demand in the Highlands, Crescent Hill and Old Louisville is booked well ahead and rates in that stretch bear no relation to the rest of the year. Underneath it, the Victorian heritage stock supports a conservation-grade rate that ordinary maintenance work does not.
Old Louisville is the reason to hire someone. It holds the largest concentration of Victorian residential in the state and one of the largest in the country, with leaded, stained and wavy single-pane glass in original sash — irreplaceable assemblies where a blade or a wet came joint does permanent damage. Cast-iron facade runoff is the other specialist problem, because rust staining needs a different chemistry from mineral haze.
OPEN COST ESTIMATOR →2025 annual mean at the Cannons Lane monitor, 2730 Cannons Lane, Bowman Field, 7.1 km north of the city (EPA site 21-111-0067).
2025 annual mean at the Durrett Lane (Near Road) monitor, 1517 Durrett Lane, 6.5 km north-west of the city (EPA site 21-111-0075).
Largest air release: Ford Motor Co Kentucky Truck Plant, 3001 Chamberlain LN (transportation equipment), inside the city limits, 441,519 lb in 2024.
Anywhere in Louisville Metro it is unlawful to open, close or operate a fire hydrant, flushing connection or other public water facility without a written permit in the Louisville Water Company's form, carried on site and shown to any Metro official who asks. Firefighters on duty and the company's own staff are the only exceptions, and a backflow preventer is required.
Louisville Metro Code §52.01: permit required for operation of public water facilities · checked September 2026
Louisville's storm drains are MSD's, and its discharge regulations make it a violation anywhere in Jefferson County to send wastewater or other polluted water into the stormwater system without treatment. Commercial wash water from cleaning vehicles or equipment is named among the banned discharges, and MSD can order the offender to fix it.
Louisville MSD Wastewater/Stormwater Discharge Regulations (2020), §§5.05–5.07 · checked September 2026
Louisville Metro has eight preservation districts, among them Old Louisville, Butchertown, Clifton and the Cherokee Triangle, plus individual landmarks. No one may make any exterior alteration to a landmark or a structure in one of those districts without a certificate of appropriateness, which the code says is issued free of charge.
Louisville Metro Code §32.252: historic preservation districts · checked September 2026
Wet-only handling. Peak mid-April. Pollen lifts cleanly with water plus light alkaline soap; do not scrape.
Pre-1880 cast-iron-facade buildings leach iron-oxide runoff onto windows below facade. Containment protocols required. Pressure-rinse without containment will accelerate damage to both facade and glass.
Not a contaminant but a scheduling constraint that defines the spring calendar. Build calendar backwards from Derby. Production-rate management through compression window is the operational challenge.
Louisville Water publishes 128 mg/L, seven and a half grains per gallon, which crosses just over the line into hard. The mineral load alone is manageable.
Residential window cleaning in Louisville typically runs $10–16 per pane or $300–550 for a standard single-story exterior. Derby week is the most concentrated pricing window in the market: residential and commercial demand in the Highlands, Crescent Hill and Old Louisville is booked well ahead and rates in that stretch bear no relation to the rest of the year.
Louisville's drier, frost-free months are July to October, by NOAA's 1991–2020 normals for the Louisville Bowman Field station, where May brings the most rain. The calendar on this page marks July (after the April 9 bloom) and October (after smoke season and before frost). Frost nights usually run from November 3 to April 3.
Yes, if the rinse is squeegeed off before it dries: Louisville Water Company publishes dissolved solids of 225 mg/L, between this site's two dissolved-solids flags. Water left to dry leaves mineral scale; fresh spots lift with a mild acid. Treatment starts with powdered activated carbon, permanganate, pre pH adjustment and coagulation.
In Louisville the dominant residue patterns include iron-stained runoff from cast-iron main street facades and ohio valley spring pollen through the derby-week window. Derby week in early May is the fixed point the rest of the year arranges itself around, and it lands in the middle of the Ohio Valley pollen season.
Old Louisville is the reason to hire someone. It holds the largest concentration of Victorian residential in the state and one of the largest in the country, with leaded, stained and wavy single-pane glass in original sash — irreplaceable assemblies where a blade or a wet came joint does permanent damage.
Pre-1900 Victorian heritage residential concentration — substantial leaded, stained, and wavy-glass single-pane. NuLu / Butchertown and Highlands have their own housing stock and glazing as well.
Just over the Kentucky line