Sioux Falls water runs 168 to 250 mg/L hard, local quartzite masonry sheds abrasive grit, and the exposed growth edge takes wind-driven prairie dust.
Sioux Falls blends very hard water from its own plant with Lewis & Clark water, which is hard, so every address gets hard water and a treated final rinse helps. Quartzite masonry sheds abrasive grit and prairie wind drives dust onto the growth edge, which leaves July to September as the working window. Roughly six usable months carry the year, so capacity inside them is what a quote is really selling; a single-story exterior runs $240 to $400.
The city publishes hardness for each source in its 2025 water quality brochure: water from its own plant averages 250 mg/L — 15 grains on its own softener-setting line — and Lewis & Clark water averages 168, or 10 grains. Very hard on one side of the blend and hard on the other, so plan for deposition and keep panes wet through a job; which source dominates an address moves with the mix.
Figures by source, as reported.
| Hardness | 168–250 mg/L as CaCO₃ 250 on average from the city's own plant and 168 from Lewis & Clark water, so which source reaches an address decides, as published by City of Sioux Falls Water. |
|---|---|
| pH | 8.3–8.7 |
| Alkalinity | 55–73 mg/L as CaCO₃ |
| Iron | 0.04 mg/L |
| Manganese | < 0.05 mg/L |
| Sodium | 34–82 mg/L |
| Chloride | 15–36 mg/L |
| Disinfectant | free chlorine |
| Source and treatment | Surface water, per the EPA SDWIS federal record · Powdered activated carbon and permanganate, coagulation, rapid mix, lime and soda ash softening with pH adjustment, sedimentation and filtration, post-chlorination, fluoridation and a polyphosphate inhibitor · The plant softens. |
Not in the report: corrosion index and total dissolved solids.
SOURCE · City of Sioux Falls 2024 Water Quality Report (2024 data), additional parameters of interest table; the most recent edition reached in this pass · How we source these numbers
The season is the dominant constraint and it is short. Reliable exterior work runs from roughly late April to October, and everything accumulated across a severe winter arrives at once on the first spring visit — salt, sand and months of untouched film together. Inside the season, wind-driven dust is close to continuous on the exposed edge of the city, and grease film near the processing corridor runs on its own interval. Mineral deposition is a steady background throughout.
SOUTH DAKOTA SEASON BY SEASON →Sioux Falls blends local aquifer supply with water brought in through a regional system, so the mix is not fixed. The city's own 2025 water quality brochure prints hardness for both halves of the supply: 250 mg/L on average from the city's plant and 168 from Lewis & Clark water — very hard and hard, which is why a single city figure would mislead. The local quartzite is the distinctive hazard: harder and more abrasive than most building dust.
Sioux Falls draws on a combination of local aquifer supply and water brought in through a regional system, so the mix is not fixed and a single figure would describe an average rather than a constant.
The city's own brochure puts hardness at 250 mg/L on average from its plant and 168 from Lewis & Clark, and even prints the softener setting for each: 15 and 10 grains per gallon.
The figures sit in an 'additional parameters of interest' table rather than the regulated tables, which is why a search of the state template alone misses them.
Northern plains aquifer water is characteristically mineral-bearing, so real deposition is the safe planning assumption even without a number — but the specific value is genuinely unknown and no substitute is asserted.
The local building stone is a genuinely unusual operational factor. Sioux Falls quartzite is a hard, pink, abrasive rock quarried locally and used extensively in the older civic and commercial buildings.
Grit from weathering quartzite masonry is harder than most building dust and will mark glass if dragged across it dry, so flooding the surface first matters more here than the age of a building would suggest.
Winters are among the most severe on this site, closing reliable exterior work for a long stretch and leaving road salt and sand on lower elevations for months at a time.
That makes the spring reopening the single heaviest service of the year, and it means a business here has to carry a full year's revenue in a compressed season.
The two large medical systems are the defining commercial clients and they run on procurement, insurance thresholds and scheduling constraints rather than on price, which makes them the most stable work in the region.
Food processing adds an organic and greasy airborne component near the plants that ordinary glass cleaner smears rather than lifts.
Wind off the open plains is a constant, and the newer subdivisions on the growth edge have little mature planting to intercept the dust it carries.
Season compresses the year into roughly six usable months, and capacity inside that window is what a Sioux Falls operation is really selling. The medical systems are the anchor accounts and price on reliability and compliance rather than rate. Historic district residential prices on pane count and care. The growth-edge subdivisions price on route density, which is excellent, offset by the shorter intervals that wind-driven dust forces.
Suburban glass is straightforward in the warm months. The rule that matters locally is never to work dry, because quartzite grit and prairie dust are both abrasive and will mark a coated pane permanently — flood first, every time. Grease near the processing plants needs a degreaser rather than more effort. The historic districts hold original divided-light sash with old putty, and the medical campuses are procurement and scheduling work rather than technical difficulty.
OPEN COST ESTIMATOR →2025 annual mean at the SF-USD monitor, 4801 N Career Ave, 7.7 km north-west of the city (EPA site 46-099-0009).
Largest air release: Design Tanks LLC, 612 W Blackhawk ST (plastics and rubber), inside the city limits, 61,725 lb in 2024.
Sioux Falls bans wasting water while watering, and ties outdoor use to the Big Sioux River's flow: lawn watering is barred from noon to 5 p.m. and runs on an odd-even address schedule when the river is at normal levels, with tighter limits as the flow drops. Check the current flow stage before a big exterior wash.
Sioux Falls Code §52.003.1 and §52.005: regulated uses of water; wasting water prohibited · checked September 2026
Sioux Falls routes only storm water and other unpolluted drainage to its storm sewers, and even clean process or cooling water needs the city engineer's approval to go there. The nuisance code also bans putting slops or filth of any kind, fluid included, into the Big Sioux River or any pool of water, so detergent rinse water belongs in a sanitary drain, not the curb inlet.
Sioux Falls Code § 53.023(a): prohibited use of public sewers, unpolluted water · Sioux Falls Code § 92.071(j): nuisances, polluting the river · checked September 2026
Permits touching Sioux Falls's historic districts, Cathedral and Downtown among them, come before the city's Board of Historic Preservation, which rules whether the work has an adverse effect before staff sign off. In July 2023 a Cathedral-district owner got approval to replace every window only on condition that the new units match original sizes and staff review the window schedule before ordering.
Sioux Falls Board of Historic Preservation minutes, July 12, 2023 · Sioux Falls Board of Historic Preservation minutes, August 9, 2023: Downtown district window work · checked September 2026
Rural well-water with sub-micron suspended-particulate fraction. Extended citric pre-treatment (4-6 minutes) plus citric-rinse finish required. Verify chemistry on individual properties.
Statewide road-salt application produces chloride-residue on lower-pane commercial and street-level retail glass through the long winter. Wet-rinse-first protocol on commercial-grade glazing.
The city publishes hardness for each source in its 2025 water quality brochure: water from its own plant averages 250 mg/L — 15 grains on its own softener-setting line — and Lewis & Clark water averages 168, or 10 grains.
Residential window cleaning in Sioux Falls typically runs $8–13 per pane or $240–400 for a standard single-story exterior. Season compresses the year into roughly six usable months, and capacity inside that window is what a Sioux Falls operation is really selling.
Sioux Falls's drier, frost-free months are July to September, by NOAA's 1991–2020 normals for the Sioux Falls station, where June brings the most rain. The calendar on this page marks July (after the May 12 bloom and after smoke season). Frost nights usually run from October 6 to May 1.
Not as the final rinse: City of Sioux Falls Water publishes hardness of 168–250 mg/L, enough to spot as it dries, so finish with pure water. Its manganese, up to 0.05 mg/L, is at the staining level, and acid cleaners will not lift that film. Treatment starts with powdered activated carbon, permanganate, coagulation and rapid mix.
In Sioux Falls the dominant residue patterns include abrasive quartzite grit from local masonry and wind-driven prairie dust on the exposed growth edge. The season is the dominant constraint and it is short.
Suburban glass is straightforward in the warm months. The rule that matters locally is never to work dry, because quartzite grit and prairie dust are both abrasive and will mark a coated pane permanently — flood first, every time. Grease near the processing plants needs a degreaser rather than more effort.
The commercial core, late 19th and early 20th-century quartzite and brick frontage with original upper sash above restored shopfronts. The local pink quartzite is the defining material and it is unusually abrasive. All Saints and McKennan Park and The Falls and the riverfront have their own housing stock and glazing as well.
Just over the South Dakota line