Columbia water is 187 mg/L hard with 329 mg/L dissolved solids. Where aeration leaves residual iron it can stain, and road salt hits lower walls.
Columbia's water is very hard even after lime softening removes about half the hardness, and it carries plenty of dissolved solids, so rinse water left to dry will spot and a treated final rinse helps. Where aeration leaves residual iron it can stain, road salt hits lower walls in winter, and July to October is the best stretch. Three campuses and their rental belts make the academic calendar, not the weather, set capacity; a single-story exterior runs $200 to $380.
The utility's 2025 report puts a number beside its description: a 2024 sample at 187 mg/L, after lime softening that it says removes half the hardness-causing minerals. That is genuinely useful even without an absolute figure, because it tells you two things. Finished water is substantially softer than the aquifer it came from, so mineral load is moderate rather than severe. Any hardness figure you see quoted for this city needs checking against which side of the softening basin it was measured on, because a raw number would double what actually reaches the glass.
| Hardness | 187 mg/L as CaCO₃ A single 2024 result, printed as carbonate hardness, that matches the total implied by the calcium and magnesium beside it; very hard, as published by Columbia Water and Light. |
|---|---|
| pH | 8.22 |
| Iron | 0.172 mg/L |
| Manganese | 0.00842 mg/L |
| Sodium | 35.2 mg/L |
| Chloride | 31.5 mg/L |
| Total dissolved solids | 329 mg/L |
| Disinfectant | chloramine |
| Source and treatment | Well water, aerated on arrival to drive off carbon dioxide and hydrogen sulphide and to oxidise iron · Aeration, then lime softening in basins removing 50 percent of the hardness-causing minerals, then filtration through anthracite coal and sand · The plant softens. |
Not in the report: alkalinity and corrosion index.
SOURCE · City of Columbia Utilities 2025 Annual Water Quality Report (PWS MO3010181), Missouri DNR template, optional monitoring (secondary contaminants) table · How we source these numbers
Winter closes reliable exterior work and deposits salt, so the spring reopening is the heaviest visit of the year. The academic calendar then governs the rest: the summer window is when the rental stock is empty and accessible, and it arrives in far worse condition than a maintenance interval would suggest. Humid summers keep organic film active on shaded elevations, and the canopy neighbourhoods add honeydew and leaf tannin through the growing season.
MISSOURI SEASON BY SEASON →Columbia draws well water and treats it in two stages that between them define the residue here: aeration to oxidise out iron, carbon dioxide and hydrogen sulphide, then lime softening, which the utility says physically removes 50 percent of the hardness-causing minerals. That is a relative disclosure — it tells you the tap is half the well without giving either number, and it means any figure quoted for this city must be checked for raw versus finished. Three college campuses give it an institutional client base well beyond its size.
Columbia runs on well water rather than a reservoir, and the utility treats it in a way that changes the answer to almost every question a cleaner would ask about the supply.
The first step is aeration — water passes through aerators with air drawn across it, which oxidises and reduces the iron, carbon dioxide and hydrogen sulphide naturally present in the well water.
The second step is lime softening. Lime reacts with the dissolved calcium and magnesium, heavy insoluble particles form and settle in the softening basins, and the accumulated solids are piped to storage lagoons.
The utility states plainly what that achieves: the process physically removes 50 percent of the hardness-causing minerals from the water.
That single sentence is the most useful disclosure available for this city, and it is a relative figure rather than an absolute one — it tells you the finished water is half the raw water without saying what either number is.
It also means any hardness figure quoted for Columbia has to be checked for whether it describes the well water or the tap. A raw figure would overstate what actually reaches a pane by a factor of two.
Aeration for hydrogen sulphide is worth noting in its own right, because it indicates raw water with a reducing chemistry, and iron that is not fully removed leaves a coloured stain rather than a white deposit.
Softened water is also more corrosive than the hard water it came from, which is why softening utilities generally have to pay closer attention to corrosion control than filtering ones do.
Above ground, three separate college campuses in one small city give Columbia an institutional client base far out of proportion to its population, and that work runs on procurement and term dates.
The rental stock around the campuses turns over in one concentrated summer window and arrives carrying a full academic year of neglect, which is a recovery job priced as a maintenance one more often than not.
Continental winters close reliable exterior work for a stretch and leave road salt on lower elevations, so the first spring service is the heaviest of the year.
Three campuses and their rental belts mean the calendar rather than the weather sets capacity, and the summer window is the binding constraint. Turnover work should be priced on condition, not on area. Institutional contracts price on procurement and reliability and are the steadiest revenue in the city. The newer subdivisions price on route density and are the efficient end. The softened supply keeps water out of the cost equation.
Suburban glass is straightforward and the softened supply is more cooperative than the raw aquifer would be. Two things repay a professional eye. If staining is rust-coloured rather than white, it is residual iron rather than hardness, and the acidic step that lifts scale will not necessarily clear it. And rental turnover work is a recovery job rather than a clean — pricing a year of neglect as a maintenance visit is the standard local mistake.
OPEN COST ESTIMATOR →Nearest EPA particle monitor: 75 km
Largest air release: Gates Corp, 3015 Lemone Industrial Blvd (plastics and rubber), inside the city limits, 1,839 lb in 2024.
Columbia keeps no year-round watering schedule in its code. The city manager may declare a water-use emergency when a main break, big fire or equipment failure threatens fire-flow pressure, or when pumping nears 24 million gallons a day, and then sets temporary rules carrying the penalties of section 7-4.
Columbia Code §7-5: emergency water regulations and the 24 MGD trigger · checked September 2026
Columbia's storm-sewer article makes it unlawful to put anything but stormwater into the city's storm system or a creek. Its exemptions cover lawn watering, non-commercial car washing and water carrying no pollutants, so a clean-water rinse can pass while a squeegee bucket of soapy runoff cannot.
Columbia Code §12A-176: illegal discharges and the seventeen exempt flows · checked September 2026
In Columbia's historic-preservation overlay (HP-O), any construction, alteration or removal touching a feature the designating ordinance names needs a certificate of appropriateness first, whether or not a building permit is involved. Interior work is exempt unless the building is a landmark. The commission must act on a complete application within 40 days or it is deemed approved.
Columbia UDC §29-2.3(c)(8)–(9): certificate of appropriateness in the HP-O district · checked September 2026
Wet-only handling. Peak late April. Heavier in southern Missouri pine areas than northern Missouri agricultural belt.
The utility's 2025 report puts a number beside its description: a 2024 sample at 187 mg/L, after lime softening that it says removes half the hardness-causing minerals. That is genuinely useful even without an absolute figure, because it tells you two things.
Residential window cleaning in Columbia typically runs $7–12 per pane or $200–380 for a standard single-story exterior. Three campuses and their rental belts mean the calendar rather than the weather sets capacity, and the summer window is the binding constraint.
Columbia's drier, frost-free months are July to October, by NOAA's 1991–2020 normals for the Columbia University of M station, where May brings the most rain. The calendar on this page marks July (after the April 16 bloom) and October (after smoke season and before frost). Frost nights usually run from October 31 to April 5.
Not as the final rinse: Columbia Water and Light publishes dissolved solids of 329 mg/L, enough to spot as it dries, so finish with pure water. Water left to dry leaves mineral scale; fresh spots lift with a mild acid. It draws on well water, aerated on arrival to drive off carbon dioxide and hydrogen sulphide and to oxidise iron.
In Columbia the dominant residue patterns include possible iron staining where aeration leaves residual iron and winter road salt on lower elevations. Winter closes reliable exterior work and deposits salt, so the spring reopening is the heaviest visit of the year.
Suburban glass is straightforward and the softened supply is more cooperative than the raw aquifer would be. Two things repay a professional eye. If staining is rust-coloured rather than white, it is residual iron rather than hardness, and the acidic step that lifts scale will not necessarily clear it.
The downtown commercial core between the two campuses, restaurants and retail with large frontages and student trade. Evening business pushes service to early mornings. University of Missouri and East Campus have their own housing stock and glazing as well.
Just over the Missouri line