Saint Paul's water is 91 mg/L hard, or 5.34 grains, with carbonate hardness at 51 of that, and it leaves the plant at pH 9.05 for corrosion control.
Saint Paul's water is moderately hard and leaves the plant strongly alkaline, so a slowly drying pane shows a faint film rather than heavy spotting, and it clears easily if caught early. Period glazing on heritage houses cannot be worked at production speed, which sets the top of the market; in a short season, July to September is the reliable window and a single-story exterior runs $300 to $550.
Ninety-one milligrams per litre is moderately hard, and with roughly 51 of that being carbonate, the scale-forming share is the majority. On glass that means a slowly drying pane will show a faint film rather than hard spotting, and it clears easily if caught while damp. The alkalinity is the more actionable half of the picture: at pH 9.05 the supply is already basic, so cutting detergent dose does more for the finish here than any change of squeegee or cloth.
| Hardness | 91 mg/L as CaCO₃ 5.34 grains per gallon, printed by the utility alongside the mg/L figure, as published by Saint Paul Regional Water Services. |
|---|---|
| pH | 9.05 |
| Alkalinity | 51 mg/L as CaCO₃ |
| Iron | 0.0721 mg/L |
| Manganese | < 0.001 mg/L |
| Sodium | 26.6 mg/L |
| Chloride | 42 mg/L |
| Total dissolved solids | 177 mg/L |
| Disinfectant | chloramine |
| Source and treatment | Mississippi River intake at Fridley, held and pre-treated through a chain of lakes — Charley, Pleasant, Sucker and Vadnais — then carried about four and a half miles down two 90-inch conduits to the McCarrons plant in Maplewood, with ten backup wells able to meet full system demand · Lime softening and aluminium sulfate coagulation in the rapid-mix chambers, ferric chloride as flocculant aid, three flocculators, five clarifiers, granular activated carbon filters that also strip taste and odour compounds, then chlorine in the finished-water reservoir followed by ammonia to form chloramines, plus pH adjustment and fluoride. Softening takes raw water of roughly 10 grains per gallon down to 64 to 85 mg/L, about 4 to 5 grains. The rebuilt McCarrons plant adds recarbonation and ozonation alongside new softening facilities. · The plant softens. |
Not in the report: corrosion index.
SOURCE · Saint Paul Regional Water Services, February 2024 Monthly Mineral Report, EPA Secondary Standards and Physical Characteristics tables (stpaul.gov), with sodium from the SPRWS 2026 Annual Water Quality Report's unregulated-substances table (2024 sampling) and the source-water section of the same report · How we source these numbers
The winter half of the year sets everything. Road salt and grit coat low glazing from the first treatment to the final thaw, and the accumulated load comes off in one heavy spring clean. Autumn leaf fall is substantial under the boulevard planting in the college districts. Summer is straightforward, with warm water, quick work and little beyond dust. Genuinely cold spells stop outdoor washing rather than merely making it slower.
MINNESOTA SEASON BY SEASON →Saint Paul Regional Water Services tests in its own laboratory and publishes monthly, giving total hardness of 91 mg/L as calcium carbonate, or 5.34 grains per gallon, at the entry to distribution. It also splits out carbonate hardness at 51 of that 91, which is the scale-forming fraction and the part that actually shows on glass. The finished water runs at pH 9.05 — alkaline on purpose, because the utility maintains a protective coating inside the pipes to hold down lead released from service lines and household plumbing. For a window cleaner that pH matters more than the hardness number: alkaline water will not dry neutral, and it compounds an alkaline detergent rather than balancing it. Iron is low and manganese undetected, so nothing here stains. What actually governs the work is the architecture, because Summit Avenue and Cathedral Hill carry original leaded and stained glazing in quantity.
Saint Paul Regional Water Services runs its own laboratory and publishes monthly water quality figures from it, sampled at the entry to distribution. A 2024 monthly report gives total hardness of 91 mg/L as calcium carbonate, which the utility also prints as 5.34 grains per gallon.
Alongside that it records carbonate hardness of 51 mg/L against the total of 91. That split is informative: a little over half the hardness is carbonate, which is the fraction that comes out of solution as scale when water is heated or left to evaporate on a surface.
The same report puts finished pH at 9.05, which is alkaline and is the signature of a lime-softening plant rather than a neutral figure. Water at that pH does not dry neutral on glass, and it will amplify an alkaline cleaner instead of tempering it.
Dissolved solids sit at 177 mg/L with chloride at 42 mg/L. Chloride of that order in an upper-Midwest river supply reflects decades of winter road salt reaching the watershed, and it rises rather than falls through the thaw.
Iron is present but low at about 0.07 mg/L and manganese is below the detection limit, so the brown and black staining that plagues some groundwater cities in this state is not a Saint Paul problem. The residue here is mineral and alkaline rather than metallic.
The utility treats for corrosion control specifically to build a protective coating on the interior of pipes and reduce lead released from service lines, solder and household plumbing. That coating is the reason the supply is held alkaline, and it is a deliberate trade rather than an accident of the source.
The practical shape of the Saint Paul job is set by its architecture rather than its water. Summit Avenue carries one of the longest intact runs of Victorian residential building in the United States, which means original glass, leaded lights and putty that a careless blade will destroy faster than any amount of hard water ever could.
Heritage stock sets the top of this market, because period glazing cannot be worked at production speed and any crew that prices it as though it can will either lose money or do damage. A compressed season concentrates demand into spring and summer. Against that, the tight residential grid in the college neighbourhoods gives some of the best route density in the Twin Cities, which keeps ordinary domestic pricing competitive.
Postwar stock on the bluff is uncomplicated warm-season homeowner work. The Victorian districts are a different proposition entirely and the reason is the glass, not the height: leaded lights, stained panels and century-old putty need hand work and patience, and the damage from getting it wrong is permanent in a way a streak never is. Converted warehouse window walls in Lowertown are contract work on access grounds.
OPEN COST ESTIMATOR →2025 annual mean at the Ramsey Health Center monitor, 555 Cedar Street, 0.5 km north-east of the city (EPA site 27-123-0868).
Largest air release: Abbott, 177 East County Road B (miscellaneous manufacturing), 1.6 km outside the city limits, 15,354 lb in 2024.
Saint Paul's water code says no one may let water go to waste through any faucet or fixture or keep it running longer than needed, and the Board of Water Commissioners may turn off service where it judges that necessary. Automatic lawn sprinklers on the public supply must have water-conserving devices.
Saint Paul Legislative Code §91.03: water conservation · checked September 2026
Saint Paul forbids anyone to let non-stormwater discharges enter the city's storm sewer system or any surface water in the city, apart from a short list of exemptions such as NPDES-permitted discharges and firefighting. A window crew's rinse water is not on that list.
Saint Paul Legislative Code §51.03: non-stormwater discharges · checked September 2026
Saint Paul's Heritage Preservation Commission reviews and approves or disapproves city permits in a heritage preservation site for any remodeling or repair, other than painting, that changes a building's exterior appearance. New construction, moving a building and demolition are reviewed as well.
Saint Paul Legislative Code §73.06: review of permits · checked September 2026
Most relevant on commercial interior glass — building-entry storefronts collect salt-tracked residue on lower thirds throughout the winter. Twice-monthly cleaning sufficient with normal wash protocol.
Saint Paul runs on Saint Paul Regional Water Services lake or reservoir surface water at a published 91 mg/L (CaCO₃) — 5.34 grains per gallon, printed by the utility alongside the mg/L figure. Ninety-one milligrams per litre is moderately hard, and with roughly 51 of that being carbonate, the scale-forming share is the majority.
Residential window cleaning in Saint Paul typically runs $10–16 per pane or $300–550 for a standard single-story exterior. Heritage stock sets the top of this market, because period glazing cannot be worked at production speed and any crew that prices it as though it can will either lose money or do damage.
Saint Paul's drier, frost-free months are July to September, by NOAA's 1991–2020 normals for the St. Paul Downtown Airport station, where June brings the most rain. The calendar on this page marks July (after the May 11 bloom and after smoke season). Frost nights usually run from October 16 to April 24.
Yes, if the rinse is squeegeed off before it dries: Saint Paul Regional Water Services publishes dissolved solids of 177 mg/L, between this site's two dissolved-solids flags. Iron, manganese, sodium and chloride all sit under this site's flags (highest: sodium up to 26.6 mg/L). It draws on Mississippi River intake at Fridley, held and pre-treated.
In Saint Paul the dominant residue patterns include published total hardness of 91 mg/l (5.34 grains), with carbonate hardness at 51 of that total and finished water at ph 9.05, alkaline by design for corrosion control. The winter half of the year sets everything.
Postwar stock on the bluff is uncomplicated warm-season homeowner work. The Victorian districts are a different proposition entirely and the reason is the glass, not the height: leaded lights, stained panels and century-old putty need hand work and patience, and the damage from getting it wrong is permanent in a way a streak never is.
One of the longest surviving stretches of Victorian residential architecture in the country, with original sash, leaded lights and stained glass in quantity. Conservation-grade work and no tolerance for a standard scraper. Cathedral Hill and Lowertown have their own housing stock and glazing as well.
Just over the Minnesota line