Mobile's tap water is soft at 38.3 to 49.6 mg/L. The real enemy on bayfront glass is chloride aerosol off Mobile Bay, plus hurricane-driven salt spray.
Mobile's tap water is soft and nearly unbuffered, so mineral spots are not the problem; chloride-laden salt air off Mobile Bay and hurricane spray are. Hurricane season aside, March to May and October to November give the best washing weather. Bayfront and eastern-shore homes need several times the visits of inland ones, and a single-story exterior runs $240 to $430.
Mobile's tap water is soft — MAWSS publishes 38.3 to 49.6 mg/L — and the mineral load is effectively irrelevant to the work. Two other published numbers are not. Alkalinity is around 10 mg/L, nearly unbuffered, and the utility's own saturation index sits near -1.9, meaning the water dissolves deposits rather than forming them. What lands on Mobile glass comes off the bay instead: chloride aerosol is hygroscopic, so it will not dry to a crust that can be scraped, and it reactivates every time the humidity climbs. That is a scheduling problem, not a chemistry one.
| Hardness | 38.3–49.6 mg/L as CaCO₃ No band label published; both endpoints are SOFT on the USGS ladder. |
|---|---|
| pH | 6.8–8.5 |
| Alkalinity | 10 mg/L as CaCO₃ (range 8–12) |
| Corrosion index | Langelier index -1.54 to -1.19 — undersaturated: this water dissolves scale rather than depositing it |
| Manganese | 0.0021 mg/L |
| Sodium | 4 mg/L (range 3.4–4) |
| Chloride | 8 mg/L |
| Total dissolved solids | 65–71 mg/L |
| Disinfectant | free chlorine |
| Source and treatment | Surface water, per the EPA SDWIS federal record · Coagulation, pre pH adjustment, flocculation, sedimentation, rapid sand filtration, chlorine dioxide, pre and post chlorination and fluoridation, with an orthophosphate inhibitor and post pH adjustment for corrosion control · No softening step. |
Not in the report: iron.
SOURCE · Mobile Area Water and Sewer System 2025 Consumer Confidence Report, standard list of secondary drinking water standards, with the EPA SDWIS federal treatment record, PWS AL0001005 · How we source these numbers
Proximity to the water sets everything. First-row bayfront glass reloads with chloride within days and stays visibly hazed through any humid spell, while a property a few miles inland runs a normal seasonal interval. Hurricane season is the discontinuity: a single named storm drives salt and organic debris across the whole market at once and converts maintenance schedules into restoration work overnight.
ALABAMA SEASON BY SEASON →MAWSS draws Big Creek Lake, a coastal-plain impoundment on sand rather than limestone, and its 2025 report puts hardness at 38.3 to 49.6 mg/L — soft — so the tap is not the issue here. Mobile Bay chloride aerosol lands directly on bayfront and eastern-shore glass, is hygroscopic, and reactivates in overnight humidity regardless of rinse-water quality, which makes distance from the bay the clearest pricing variable in the market. De Tonti Square and Church Street East hold irreplaceable pre-1850 glazing, and hurricane season converts the whole book to restoration work in a day.
Mobile Area Water and Sewer takes all of its water from one impoundment, Converse Reservoir — Big Creek Lake — whose 103-square-mile watershed lies entirely inside Mobile County, and treats it at the Stickney and Myers plants. The published hardness is 38.3 to 49.6 mg/L with magnesium barely detectable, alkalinity around 10, and a corrosivity index near -1.9, which together describe a soft, lightly buffered and mildly aggressive supply rather than a scale-forming one.
The salt that matters here does not come from the tap. Mobile Bay brackish aerosol deposits chloride directly onto glass along the bayfront and eastern shore, and that loading is entirely independent of what the drinking water reads — a pure-water rinse system does nothing about it.
Chloride film is hygroscopic, which is why bayfront glass can look worse an hour after cleaning on a damp morning. It pulls moisture back out of humid Gulf air instead of drying to a removable crust, so the working window is the middle of the day and a job finished at dusk greets the customer hazed.
De Tonti Square and Church Street East hold pre-1850 antebellum housing with original glass and leaded fanlights above the doors. That glazing predates float manufacturing, sits unevenly in its frames and has no like-for-like replacement, so conservation pacing is the standard and a blade is the wrong tool.
Hurricane season is a discontinuity rather than a seasonal trend. One named storm drives salt spray and organic debris across the entire market simultaneously, converting every maintenance schedule into restoration work and putting embedded grit in frames and screens that has to be floated off rather than dragged.
The port and the industrial waterfront add diesel particulate to the salt on commercial glass. That combination is oily and saline at once, which defeats detergents chosen for either problem alone — those accounts need a surfactant step and a neutralising rinse rather than one or the other.
Distance from the bay is the clearest pricing variable in the market, because it maps directly onto how often the work has to be repeated. Bayfront and eastern-shore properties need several times the frequency of inland equivalents and should be sold as a different product. Port and industrial waterfront work adds diesel particulate and its own access constraints on top.
Routine inland work is manageable. Two things are not. The antebellum districts hold pre-1850 glass in original sash with leaded fanlights, where the glazing predates float manufacture and cannot be replaced — conservation pacing, no blades. And bayfront salt film needs a genuine rinse-and-neutralise routine rather than a wipe, because dry-wiping hygroscopic chloride grinds it into the surface instead of lifting it.
OPEN COST ESTIMATOR →2025 annual mean at the James Seals Jr. Park and Recreation Center monitor, James Seals Jr. Park and Recreation Center, 540 Texas St, 6 km east of the city (EPA site 01-097-8001).
2025 annual mean at the Chickasaw monitor, Iroquois and Azalea, Chickasaw, Mobile CO., Alabama, 11.5 km north of the city (EPA site 01-097-0003).
Largest air release: Alabama Shipyard LLC, 660 Dunlap DR (transportation equipment), inside the city limits, 59,655 lb in 2024.
Mobile's water utility, MAWSS, prints no watering schedule, hose-nozzle rule or drought stage in its 2026 Policy and Procedure Manual. The rule a window cleaner can trip is its hydrant policy: drawing water from a MAWSS hydrant, to fill a water-fed-pole tank for example, needs a permit and a MAWSS-installed meter and backflow assembly, and unauthorized use can cost up to $1,000 a day.
MAWSS, Policy & Procedure Manual (2026 edition) · MAWSS, fire hydrant use policy and temporary meter permits · checked September 2026
Mobile prohibits putting anything other than stormwater, including water that carries pollutants, into its storm sewer system or watercourses unless one of the code's exceptions covers it. Soapy rinse water from glass cleaning needs to be caught rather than hosed into the gutter.
Mobile City Code §17-11: illicit discharge detection and elimination · checked September 2026
Once Mobile designates a local historic district by ordinance, no exterior material change may be made to any property or site in it, and no building erected or demolished there, without a certificate of appropriateness. The review asks whether the change fits the character of the historic property or district.
Mobile City Code §44-77: certificates of appropriateness · Mobile City Code §44-79: standard of review · checked September 2026
Brackish-water mineral fraction composite. Heavier residue character than open-Gulf salt. Same two-pass wash protocol with slightly extended alkaline-soap dwell on bay-front compared to ocean-front.
Mobile's tap water is soft — MAWSS publishes 38.3 to 49.6 mg/L — and the mineral load is effectively irrelevant to the work. Two other published numbers are not.
Residential window cleaning in Mobile typically runs $8–13 per pane or $240–430 for a standard single-story exterior. Distance from the bay is the clearest pricing variable in the market, because it maps directly onto how often the work has to be repeated.
Mobile's drier, frost-free months are March to May and October and November, by NOAA's 1991–2020 normals for the Mobile Downtown Airport station. The calendar on this page marks March (after the February 24 bloom), October (after smoke season) and November (before frost). Frost nights usually run from December 6 to February 21. Normal highs reach 90°F in June to August.
Usually yes: Mobile Area Water and Sewer System publishes dissolved solids of 65–71 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: chloride up to 8 mg/L). Treatment starts with coagulation, pre pH adjustment, flocculation and sedimentation.
In Mobile the dominant residue patterns include mobile bay chloride aerosol on bayfront and eastern-shore glass and hurricane-driven salt spray and organic debris across the market. Proximity to the water sets everything.
Routine inland work is manageable. Two things are not. The antebellum districts hold pre-1850 glass in original sash with leaded fanlights, where the glazing predates float manufacture and cannot be replaced — conservation pacing, no blades.
Pre-1850 antebellum residential with original glass and leaded fanlights. Irreplaceable glazing, conservation pacing, and no blades — the highest-risk work in the city. Downtown / Lower Dauphin Street and Oakleigh Garden District have their own housing stock and glazing as well.
Just over the Alabama line