Window Washing in Houston
Houston water ranges from 44 to 229 mg/L hard depending on source, so sprinkler spotting varies across the city, and oak pollen adds a spring film.
Houston's water swings from soft to very hard through the year depending on the source, but humidity shapes the result more: glass dries slowly, which gives film and haze time to settle, and oak pollen adds a spring layer on top. Wash from February to May or in October and November, either side of the steamy months. With two high-rise cores and a big premium housing market, Houston prices at metro rates: $320 to $540 for a single-story exterior.
What the water means for the glass
At 135.5 ppm on average the supply will mark dark glass in sun without damaging it, though the swing from 43.5 to 229 across the year makes some weeks much harder than others — still well below what the local softener market claims. The number that actually shapes a result here is humidity rather than hardness: slow dry-down gives residue time to settle and re-wet, so technique and frame drying matter more than rinse chemistry.
Houston tap water, by the numbers
| Hardness | 44–229 mg/L as CaCO₃ Averaging 136 mg/L; the Main System figure; two smaller systems in the same report print 124 and 160 to 167, as published by Houston Public Works. |
|---|---|
| pH | 7.8 (range 7.3–8.3) |
| Iron | 0.08 mg/L (range 0–1.02) |
| Manganese | 0.01 mg/L (range 0–0.06) |
| Chloride | 38.4 mg/L (range 28–49) |
| Total dissolved solids | 260 mg/L (range 146–331) |
| Disinfectant | uv + chloramine |
| Source and treatment | Surface water, per the EPA SDWIS federal record · Permanganate and powdered activated carbon, pre pH adjustment with lime or caustic, coagulation, flocculation, rapid mix, sedimentation and rapid sand filtration, sequestration for iron and manganese, chlorine dioxide, ultraviolet radiation and chlorination with chloramines as the residual, fluoridation, with a polyphosphate inhibitor and post pH adjustment · No softening step. |
Not in the report: alkalinity, corrosion index and sodium.
SOURCE · Houston Public Works 2025 Water Quality Report, Main System TX1010013 secondary-standards table · How we source these numbers
When a wash holds
What sets the cleaning clock
Humidity and storms set the calendar. Mildew on shaded trim rebuilds continuously through the warm months and needs attention on a shorter cycle than the glass itself, while hurricane season converts the whole coastal side of the city into restoration work on no notice. Oak pollen adds a spring spike on top of both.
TEXAS SEASON BY SEASON →What's specific to Houston
Houston Public Works' 2025 report puts the Main System's total hardness at 135.5 ppm on average, 43.5 to 229 across the year — hard on average, soft to very hard at the extremes, and nothing like the flat very-hard figure the market assumes. Finished pH is 7.7 and total dissolved solids 242. The operating reality is shaped by humidity, hurricane season and the scale of the high-end residential inventory rather than by mineral load.
The city's 2025 report gives the Main System's total hardness as 135.5 ppm on average, from 43.5 to 229 across the year, while two smaller systems in the same report print 124 and 160 to 167. That is a wide year-to-year move on a blended surface supply, and it straddles the boundary between moderately hard and hard — so a rinse policy set in one year may be wrong the next.
Hardness figures quoted online for Houston often run well above the utility's own. You may see 17.2 grains; Houston Public Works' published average is less than half that. The high claims are being made about the metro, not the city system, and the distinction matters commercially.
That metro-versus-city distinction is real and it is worth knowing before quoting. The city system runs on blended surface water from Lake Houston and Lake Conroe; many of the surrounding municipal utility districts in the northern and western suburbs run on groundwater and genuinely are far harder. A crew working across the county line is working different water.
Finished pH is 7.7 — near neutral, and unusual on this site, where most large systems run alkaline for corrosion control. A cleaner behaves closer to its label here than in San Francisco or Fargo, which is one fewer variable to manage.
Gulf humidity is the dominant operational problem, not minerals. Dry-down is slow, mildew builds persistently on north-facing trim and frames, and a wash is not finished until the frame is dried — leave it wet and the glass re-spots from the frame within hours.
Hurricane and tropical-storm debris film is a category of its own. Even a depression leaves a salt-and-particulate residue on coastal-facing glass that must be presoaked and flooded before any contact; wiping it drags grit across the pane.
Downtown and the Galleria give Houston two separate high-rise cores rather than one, both on institutional and quarterly contract cycles. That is unusual and it means the commercial book here is larger and more geographically split than in most cities of comparable size.
The Heights is a pre-1920 Victorian and Craftsman preservation district with original wood sash in quantity, so heritage handling is routine on one side of the city while River Oaks and the Galleria are large modern fixed glazing on the other.
How old the glass is
- Before 1940 · 4%wood sash and older glass
- 1940–1959 · 13%steel casements, early aluminium
- 1960–1979 · 30%aluminium sliders, often single-pane
- 1980–1999 · 23%double-pane units become standard
- 2000–2009 · 14%vinyl frames, low-E spreading
- 2010 or later · 17%low-E common: gentle cleaners only
The city, by neighborhood
What window cleaning costs in Houston
Two high-rise cores and a very large premium residential base put this market on metro-tier pricing, with downtown and the Galleria priced on rigging and building coordination. Humidity lengthens the job through frame drying, and storm response is the volatile element — an unplanned surge that resets schedules city-wide.
Doing it yourself
Moderately hard water and accessible suburban glazing keep a homeowner result realistic, and the honest caution is procedural rather than chemical: leaving frames wet in Gulf humidity is what causes the re-spotting most people blame on the water. Storm debris is the genuine exclusion, because it must be flooded rather than wiped, and the two high-rise cores are regulated access work.
OPEN COST ESTIMATOR →2025 annual mean at the Lang monitor, 4401 1/2 Lang Rd, 11.1 km north-west of the city (EPA site 48-201-0047).
2025 annual mean at the Houston North Loop monitor, 822 North Loop, 3.2 km north of the city (EPA site 48-201-1052).
Largest air release: Lyondell Chemical Co, 2502 Sheldon RD (chemicals), 1.3 km outside the city limits, 1,135,930 lb in 2024.
Houston's current-restrictions page shows Stage 1 of the Drought Contingency Plan rescinded on May 29, 2024, with no stage in force. When the plan's stages return, the city first asks that power washing be kept to health and safety needs and in a later stage permits it only for those reasons, and it classes washing buildings or paved surfaces as non-essential water use.
Houston Public Works, current watering restrictions · City of Houston, 2024 Drought Contingency Plan · checked September 2026
Houston's code makes it an offense to put anything but storm water into the city's storm sewer system. Wash water made with plain drinking water and no detergents or surfactants, similar to street wash water, is a listed defence, so a plain rinse is tolerated but soapy or chemical window-cleaning water has to be kept out of the drains.
Houston Code of Ordinances §47-741: discharge to MS4 prohibited · checked September 2026
Under a December 2025 city policy, Houston bars vinyl windows on landmarks, protected landmarks and buildings in historic districts unless a specific exception applies, and street-visible window replacement on those properties goes through a Certificate of Appropriateness from the Historic Office of Preservation. Replacement windows must keep the building's historic appearance.
City of Houston Planning & Development, Policy 1-1: Window Replacement (Historic Office of Preservation) · checked September 2026
What actually shows up on Houston glass
Live oak and post oak release pollen from late February through early April. Yellow-green pollen layers everywhere in Austin, San Antonio, and the eastern hill country. Heavy enough to require a pre-rinse on most spring jobs.
Heaviest in San Antonio, whose published figure is the extreme end, and on hill-country well systems. Lower-third of patio doors and ground-floor windows accumulate visible mineral cement within a single summer.
Houston, answered
How hard is the water in Houston, Texas?＋
At 135.5 ppm on average the supply will mark dark glass in sun without damaging it, though the swing from 43.5 to 229 across the year makes some weeks much harder than others — still well below what the local softener market claims.
How much does window cleaning cost in Houston?＋
Residential window cleaning in Houston typically runs $11–16 per pane or $320–540 for a standard single-story exterior. Two high-rise cores and a very large premium residential base put this market on metro-tier pricing, with downtown and the Galleria priced on rigging and building coordination.
When is the best time of year to clean windows in Houston?＋
Houston's drier, frost-free months are February to May and October and November, by NOAA's 1991–2020 normals for the Houston-Port station, where June brings the most rain. The calendar on this page marks March (after the February 14 bloom) and October (after smoke season). Frost nights usually run from December 25 to February 2. Normal highs reach 90°F in June to September.
Can I rinse windows with Houston tap water?＋
Yes, if the rinse is squeegeed off before it dries: Houston Public Works publishes dissolved solids of 260 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 permanganate, powdered activated carbon, pre pH adjustment with lime or caustic and coagulation.
Why do my windows look dirty so quickly in Houston?＋
In Houston the dominant residue patterns include oak pollen and hard-water sprinkler overspray. Humidity and storms set the calendar. Mildew on shaded trim rebuilds continuously through the warm months and needs attention on a shorter cycle than the glass itself, while hurricane season converts the whole coastal side of the city into restoration work on no notice.
Do I need a professional to clean my windows in Houston?＋
Moderately hard water and accessible suburban glazing keep a homeowner result realistic, and the honest caution is procedural rather than chemical: leaving frames wet in Gulf humidity is what causes the re-spotting most people blame on the water.
What sets Downtown Houston apart for window cleaning in Houston?＋
High-rise commercial and converted-loft residential; institutional tenants and quarterly contract work. Montrose and River Oaks have their own housing stock and glazing as well.
Other cities we cover in Texas
Nearby cities in neighboring states
Just over the Texas line