Columbia's water is soft, averaging 36 mg/L within a 20 to 47 range that depends on which of two plants serves you, with calcium at just 12.0 mg/L.
Columbia's water is soft whichever of its two plants serves you, so mineral spotting is effectively off the list; if glass looks bad, the cause came out of the air. Mild winters allow year-round work, though summer heat shortens the day, and April and September to November are the best months. That long season spreads costs in a way northern markets cannot, and a single-story exterior runs $240 to $430.
An average of 36 mg/L against a published span of 20 to 47 puts Columbia firmly in soft territory, and the practical consequence is that the tap is never the limiting factor on a finish here. Mineral spotting is effectively off the differential diagnosis. If glass in this city dries badly the explanation is almost always speed — the water evaporated before it was cleared — and the fix is the hour of the day and the size of the section being worked, not the water.
| Hardness | 20–47 mg/L as CaCO₃ Soft, averaging 36 mg/L as calcium carbonate, as published by Columbia Water (City of Columbia Department of Utility Operations). |
|---|---|
| pH | 7.9 (range 7.5–8.6) |
| Alkalinity | 26.4 mg/L as CaCO₃ (range 20–33.2) |
| Iron | < 0.05 mg/L |
| Manganese | 0.0011 mg/L (range 0–0.01) |
| Sodium | 7.3 mg/L (range 5–12) |
| Chloride | 10.8 mg/L (range 7.72–13.9) |
| Disinfectant | chloramine |
| Source and treatment | Surface water, per the EPA SDWIS federal record · Pre pH adjustment, coagulation, flocculation, rapid mix, sedimentation, rapid sand filtration and sludge treatment, chlorine dioxide and pre-chlorination with chloramines as the residual, fluoridation, with an orthophosphate inhibitor and post pH adjustment · No softening step. |
Not in the report: corrosion index and total dissolved solids.
SOURCE · City of Columbia 2025 Water Quality Report, secondary-parameters and 2025 Non-Regulated Parameters tables · How we source these numbers
Pollen dominates the spring and it is heavy under the old canopy, arriving in a yellow layer that coats everything for several weeks rather than settling gradually. Summer heat is the operational constraint from June through September, shortening the usable working window to the early morning on any sunlit elevation. Autumn brings leaf fall in the canopied districts. Winters are mild enough that outdoor work continues year-round, which is a genuine advantage over most of this site.
SOUTH CAROLINA SEASON BY SEASON →Columbia publishes hardness in a table it says is there for technical users, and the figure is low: 20.0 to 47.0 mg/L as calcium carbonate, averaging 36.0, with calcium at 12.0 and magnesium at 2.10. That is soft water, which takes the rinse question off the table entirely — no part of this city needs treated water to finish a pane. The published range reflects real structure rather than noise, because the city runs two plants on two sources, the Broad River through the Columbia Canal and Lake Murray, and reports many parameters separately for each. The Canal supply is changing: an alternate Congaree River intake with up to sixty million gallons a day of capacity began construction in late 2025 to reduce sole reliance on the canal after the 2015 flood. What actually shapes the work is heat. Midlands summers are severe enough that sunlit glass flash-dries a rinse, which is a desert-city constraint in a place nobody expects one.
Columbia publishes hardness, and it does so in a table it explicitly says exists for technical users. The 2025 report's non-regulated parameters give hardness as calcium carbonate ranging from 20.0 to 47.0 mg/L with an average of 36.0, and the city notes the table may be useful for those using water for specialised purposes like brewing or maintaining chillers and boilers.
An average of 36 mg/L is soft water, and the supporting numbers make the same case: calcium averages 12.0 mg/L, magnesium 2.10 and alkalinity 26.4. There is very little mineral in this supply to leave behind.
The range from 20 to 47 has a structural explanation. Columbia runs two plants on two different surface sources — the Broad River by way of the Columbia Canal, and Lake Murray — and which plant serves an address moves the figure within that span.
Those two plants are visible throughout the report, not just in the hardness row. Chlorite, chlorine dioxide and even the PFAS results are reported separately for the Lake Plant and the Canal Plant, which is a level of per-plant disclosure that most multi-plant utilities do not offer.
For glass the implication is that no part of Columbia needs treated rinse water. At 36 mg/L average a tap rinse dries clean, and mineral spotting is not a plausible diagnosis for a poor finish anywhere on this system.
The city is adding resilience to the Canal supply after the October 2015 flood. Construction began in late 2025 on an alternate intake drawing from the Congaree River with up to sixty million gallons per day of pumping capacity, reducing sole reliance on the Columbia Canal — so the source mix behind the Canal Plant is actively changing.
What governs the work here is climate rather than chemistry. Columbia runs some of the most severe summer heat in the eastern United States, and glass in direct sun through a Midlands July will flash-dry a rinse before a squeegee crosses it. That is a scheduling constraint identical in kind to the desert cities, in a place nobody expects it.
A year-round season is the structural advantage here, because mild winters let crews work twelve months and spread fixed costs in a way northern markets cannot. Against that, summer compresses the productive hours of the day, so July and August capacity is worth more than the calendar suggests. Institutional and campus contracts provide a stable base. Soft water means no crew needs to price treated rinse capacity into anything.
For most of the year and most of the housing stock this is easy homeowner work with forgiving water. Summer is the exception and it is a real one: attempting a large sunlit pane at midday in July guarantees a poor result no matter how good the technique, and most people learn that the hard way rather than adjusting the schedule. Converted industrial glazing in the riverside district and institutional frontage around the campus are contracted markets.
OPEN COST ESTIMATOR →2025 annual mean at the Parklane monitor, 8311 Parklane Road [Parklane], 7.9 km north-west of the city (EPA site 45-079-0007).
Largest air release: SEA-Hunt Boat Manufacturing Co Inc, 2348 Shop RD (transportation equipment), 0.4 km outside the city limits, 253,910 lb in 2024.
When drought or any other condition affecting the supply makes it necessary, Columbia's city manager can declare that conditions prevent the usual water-use demands and restrict use across the service area, with notice to council.
Columbia City Code §23-70: authority of city manager to restrict use during water shortage · checked September 2026
In Columbia it is unlawful to connect any pipe, open channel or other conveyance that discharges anything but stormwater, or unpolluted water the stormwater division has approved, into receiving waters, and unlawful to keep such a connection running.
Columbia City Code §21-48: illicit connections, illicit discharges and improper disposal · checked September 2026
Columbia calls its approval a Certificate of Design Approval, issued by the Design/Development Review Commission or its preservation staff for work on landmarks and in protected districts such as Old Shandon/Lower Waverly and Cottontown/Bellevue. The city's window guidance notes most protected buildings must keep their openings, so replacement units have to be sized to the original, often non-standard, opening.
City of Columbia Planning, window review guidance for historic properties · Columbia Design/Development Review Commission minutes, June 2024 · checked September 2026
Three to four week yellow film deposition on horizontal and east-facing vertical glass. Wet-only handling. Do not scrape. Heaviest pollen-deposition state in the country alongside Georgia and Alabama.
Pure marine aerosol on ocean-side. Lifts predictably with extended alkaline-soap dwell plus citric finish. Monthly visit frequency standard on high-end coastal residential.
Sulfur-and-mineral composite from exposed pluff-mud at low tide. Distinctive sulfur note in residue. Cleans with standard alkaline-soap dwell but customers find the smell objectionable — operators should explain.
An average of 36 mg/L against a published span of 20 to 47 puts Columbia firmly in soft territory, and the practical consequence is that the tap is never the limiting factor on a finish here. Mineral spotting is effectively off the differential diagnosis.
Residential window cleaning in Columbia typically runs $8–13 per pane or $240–430 for a standard single-story exterior. A year-round season is the structural advantage here, because mild winters let crews work twelve months and spread fixed costs in a way northern markets cannot.
Columbia's drier, frost-free months are April and September to November, by NOAA's 1991–2020 normals for the Columbia Owens Downtown Airport station, where June brings the most rain. The calendar on this page marks April (after the March 10 bloom), September (after smoke season) and November (before frost). Frost nights usually run from November 19 to March 13.
Usually yes: Columbia Water (City of Columbia Department of Utility Operations) publishes hardness of 20–47 mg/L, low enough that tap-rinsed glass tends to dry clean. Iron, manganese, sodium and chloride all sit under this site's flags (highest: iron up to 0.05 mg/L). Treatment starts with pre pH adjustment, coagulation, flocculation and rapid mix.
In Columbia the dominant residue patterns include soft supply averaging 36 mg/l with a published range of 20–47, varying by which of two plants serves the address and calcium averaging 12.0 mg/l and magnesium 2.10 — very little mineral to deposit.
For most of the year and most of the housing stock this is easy homeowner work with forgiving water. Summer is the exception and it is a real one: attempting a large sunlit pane at midday in July guarantees a poor result no matter how good the technique, and most people learn that the hard way rather than adjusting the schedule.
Government and commercial frontage around the capitol, with substantial institutional glazing on fixed schedules and a surviving band of early twentieth-century commercial buildings along the street. The Congaree Vista and Shandon have their own housing stock and glazing as well.
Just over the South Carolina line