Aurora's water runs 87 to 198 mg/L hard and is chloraminated. The eastern side takes wind-borne prairie dust, and arterial corridors add traffic film.
Aurora's water is hard on average and very hard at the top of its range, and it is chloraminated, so rinse water dries to visible deposits and wears pure-water resin faster. Prairie dust blows in on the eastern side and arterial roads add traffic film, which leaves July to September as the dependable window. Dust plus harder water means glass does not hold its condition as long as a quote assumes, and a single-story exterior runs $240 to $430.
Aurora Water's own table gives total hardness as 136 mg/L on average for 2025, sampled daily, across a range of 87 to 198 — hard on average and very hard at the top. That is what a plains and river-sourced metro supply does in this region, and it means real deposition on every dry-down, concentrated fast by sun on hot glass. Be ready to tell a customer why the far higher figure they may have found describes an aquifer rather than their tap.
| Hardness | 87–198 mg/L as CaCO₃ Averaging 136 mg/L; hard, as published by Aurora Water. |
|---|---|
| pH | 8.1 (range 8–8.3) |
| Alkalinity | 85.1 mg/L as CaCO₃ (range 52.2–119) |
| Iron | 0.00089 mg/L (range 0–0.0169) |
| Manganese | 0.00248 mg/L (range 0–0.0439) |
| Sodium | 36.6 mg/L (range 20–69.8) |
| Chloride | 41.8 mg/L (range 17.1–82.5) |
| Total dissolved solids | 240 mg/L (range 119–355) |
| Disinfectant | chloramine |
| Source and treatment | Surface water, per the EPA SDWIS federal record · Presedimentation, aeration and powdered activated carbon for taste and odour, permanganate, coagulation, flocculation, rapid mix, sedimentation and rapid sand filtration, granular activated carbon, peroxide and ultraviolet radiation, chlorine dioxide and chlorination with chloramines as the residual, fluoridation and pH adjustment · No softening step. |
Not in the report: corrosion index.
SOURCE · Aurora Water drinking water quality page, 2026 report data table (January to December 2025) · How we source these numbers
Dust is close to continuous on the eastern side and does not have an off-season, so exposed subdivisions need a shorter interval than their newness suggests. Sun-facing elevations become morning-only work from late spring through early autumn. Hail arrives as an event and generates unscheduled demand that is worth having capacity for. Construction dust persists as long as the next phase is going up, which on this growth edge means indefinitely. Winter is the forgiving season and the right time for unhurried work.
COLORADO SEASON BY SEASON →Aurora blends more than one kind of source, and its own 2026 report puts hardness at 136 mg/L on average across a 87 to 198 range — hard, and nowhere near the 260 that circulates for the city. That 260 is instructive rather than useful: its own source notes describe it as a county-level ambient median, which measures groundwater across a county rather than what a plant delivers to a tap. Beyond the water it is Front Range conditions: prairie dust off open ground, hail, ultraviolet at altitude, and a construction edge that generates first cleans rather than maintenance visits.
Aurora draws on more than one kind of source rather than a single mountain supply, which is the underlying reason the figures published for this city vary so widely.
The utility's own table settles it: total hardness averaged 136 milligrams per litre in 2025 across 87 to 198, while figures quoted online had run from 132 to 260.
One of those high figures is worth understanding rather than simply discarding, because it illustrates a specific and common error. The 260 value is presented as Aurora's hardness but is described in its own source notes as a county-level median drawn from ambient water-quality monitoring.
An ambient county median measures the water in the ground across a whole county. It does not measure what a treatment plant delivers to a tap, and conflating the two will always overstate a treated municipal supply in a region with mineral-rich groundwater.
That distinction matters commercially as well as technically: a customer quoting a very high hardness figure at you may be quoting the aquifer rather than their own water.
The Denver-metro pattern is that plains and river-sourced systems run considerably harder than the mountain-sourced ones, and at a 136 average this city sits firmly on the harder side of that divide.
Altitude does the rest. Ultraviolet intensity on the Front Range degrades seals and applied films faster than at sea level, and the sun heats sun-facing glass quickly enough that water flashes off before a blade arrives.
Open prairie to the east feeds wind-borne dust into the city continuously, and the eastern subdivisions have little mature planting to intercept it.
This is hail country, and hail is a genuine business factor — direct damage to glazing and screens, followed by a wave of assessment and cleaning demand.
Continuous construction on the growth edge means a steady supply of post-construction first cleans, which are heavier than maintenance work and need scoping separately.
Frequency is the driver most often underestimated, because dust and a harder supply together mean a building does not hold its condition as long as a quote assumes. The medical campus and institutional work prices on process compliance and reliability. The southeastern planned neighbourhoods price on route density and are the efficient end. The eastern edge prices on drive time and on the post-construction first cleans that keep arriving there.
Suburban glass is straightforward for a homeowner who works early and floods the surface before touching it — prairie dust is abrasive and dry-wiping a coated pane marks it permanently. The chemical caution matters here too: this stock is almost all coated, and attacking mineral spotting with a strong acid is how a low-emissivity surface gets damaged. Established etching is a restoration job rather than a cleaning one and should be described as such. Medical campus and base work is contract and clearance territory.
OPEN COST ESTIMATOR →2025 annual mean at the Birch Street monitor, 7275 Birch St, 22.7 km north-west of the city (EPA site 08-001-0010).
2025 annual mean at the Denver - NJH-E monitor, 14TH AVE. & Albion ST., 19 km west of the city (EPA site 08-031-0013).
Largest air release: Elkay Wood Products Co, 23655 E 19TH AVE (furniture), inside the city limits, 20,377 lb in 2024.
Aurora Water runs permanent conservation rules: lawns may be watered at most three days a week, not between 10 a.m. and 6 p.m. from May through September, and water waste such as heavy runoff, water pooling on or spraying onto sidewalks, driveways, gutters and streets is not allowed. A hose nozzle with a shut-off is required for car washing.
Aurora Water: watering times and landscape watering rules · checked September 2026
Aurora makes it unlawful to discharge anything into the storm drainage system that isn't entirely storm water. The exemptions are specific, such as lawn watering, hydrant flushing and individual residential car or street washing, so commercial wash water from a cleaning crew isn't among them.
Aurora City Code Sec. 138-439: prohibited discharges · checked September 2026
Aurora's development code has a Historic Protection Overlay for designated landmarks and districts. No construction, alteration or removal that would impair a landmark's or district's historic character may go ahead without a permit from the Historic Preservation Commission, whose preservation specialist first sorts the request into major or minor changes.
Aurora UDO §146-2.6.5: Historic Protection Overlay (-HPO) · Aurora UDO §146-5.4.3(D): historic landmark/district development application · checked September 2026
A single severe hail event drops golf-ball to softball-sized stones on the metro two to three times a year. The aftermath is roof-granule particulate, dissolved organic debris, and chimney soot washed across glass. Multi-pass cleaning, prioritize callers within ten days of an event.
Aurora Water's own table gives total hardness as 136 mg/L on average for 2025, sampled daily, across a range of 87 to 198 — hard on average and very hard at the top. That is what a plains and river-sourced metro supply does in this region, and it means real deposition on every dry-down, concentrated fast by sun on hot glass.
Residential window cleaning in Aurora typically runs $8–13 per pane or $240–430 for a standard single-story exterior. Frequency is the driver most often underestimated, because dust and a harder supply together mean a building does not hold its condition as long as a quote assumes.
Aurora's drier, frost-free months are July to September, by NOAA's 1991–2020 normals for the Denver-Stapleton station, where May brings the most rain. The calendar on this page marks July (after the May 3 bloom) and September (after smoke season and before frost). Frost nights usually run from October 8 to May 4. Normal highs reach 90°F in July.
Yes, if the rinse is squeegeed off before it dries: Aurora Water publishes dissolved solids of 240 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 presedimentation, aeration, powdered activated carbon for taste and odour.
In Aurora the dominant residue patterns include wind-borne prairie dust on the eastern side and traffic film along the major arterial corridors. Dust is close to continuous on the eastern side and does not have an off-season, so exposed subdivisions need a shorter interval than their newness suggests.
Suburban glass is straightforward for a homeowner who works early and floods the surface before touching it — prairie dust is abrasive and dry-wiping a coated pane marks it permanently. The chemical caution matters here too: this stock is almost all coated, and attacking mineral spotting with a strong acid is how a low-emissivity surface gets damaged.
The oldest part of the city, post-war commercial and small-house residential along a major through route. Heavy traffic film on the lower half of every frontage and the tightest margins in the market. Anschutz Medical Campus and Southeast Aurora and Southlands have their own housing stock and glazing as well.
Just over the Colorado line