New Orleans humidity grows mould and algae film on shaded walls all year, and hurricanes drive salt spray, grit and organic debris onto the glass.
The Sewerage and Water Board publishes no hardness figure, so plan around the climate instead: humidity grows mould and algae on shaded walls all year, and storms drive salt spray, grit and debris onto the glass. February to May and October to November are the best months. Historic-district rules and gallery and balcony access set the top of the market, while a typical single-story exterior runs $300 to $550.
The Sewerage and Water Board publishes no hardness figure. Mississippi River water this far downstream runs softer than the river does in its carbonate reaches, so the direction points low — but the Board treats at two plants on two banks, which is exactly the arrangement that produces per-plant publication elsewhere, and a single citywide figure may not be the right thing to look for.
Figures by plant, as reported.
| Hardness | not published Sewerage and Water Board of New Orleans publishes no hardness figure in its 2026 Consumer Confidence Report, with translations (swbno.org). |
|---|---|
| Disinfectant | chloramine |
| Source and treatment | Surface water at the Carrollton plant, per the EPA SDWIS federal record · Powdered activated carbon, coagulation, lime and soda ash softening with sedimentation and rapid sand filtration, pre-chlorination with chloramines as the residual, fluoridation, with pH adjustment and sequestration for corrosion control · The plant softens. |
Not in the report: pH, alkalinity, corrosion index, iron, manganese, sodium, chloride and total dissolved solids.
SOURCE · Sewerage and Water Board of New Orleans 2026 Consumer Confidence Report (2025 data) · How we source these numbers
Humidity never lets the glass dry down. Shaded and north-facing elevations hold moisture almost year-round, so mould and algae film re-establish in weeks and are the recurring complaint rather than spotting. Hurricane season then delivers the discontinuities: a single storm drives salt, organic debris and grit across the whole city and converts maintenance schedules into restoration work overnight.
LOUISIANA SEASON BY SEASON →The Sewerage and Water Board treats Mississippi River water at two plants, Carrollton and Algiers, and its 2026 report prints no hardness figure; river water this far downstream runs softer than most people expect. Humidity rather than mineral is the adversary — shaded glass holds mould and algae that return in weeks. Preservation control, balcony and gallery access and a tourism hospitality calendar set the top of the market, with hurricane season a recurring rather than exceptional cost.
The Sewerage and Water Board treats Mississippi River water at two plants, Carrollton and Algiers, one for each bank. The Board's 2026 report prints no hardness figure, and a two-plant system on one river is the arrangement that has produced per-plant publication in several other cities.
Mississippi River water this far downstream is softer than the same river in its Midwestern carbonate reaches, so the direction points low even though no figure is confirmed. That is the opposite of what people expect from a big-river city, and it is worth saying to customers who assume river water means hard water.
Roughly 25,000 to 30,000 lead service lines are estimated to remain in use, concentrated in neighbourhoods developed before 1950 — the French Quarter, Marigny, Bywater and older Uptown. It is a corrosion-control matter rather than a glass one, but it tells you the Board is managing an aggressive supply through a pre-war distribution system.
Humidity here does not release the glass. Shaded and north-facing elevations stay damp almost year-round, so mould and algae film re-establish within weeks and are the recurring complaint rather than mineral spotting. Those elevations need their own interval, not a share of the front's.
The French Quarter and the older faubourgs sit under preservation control, and the work there is reached from balconies and galleries rather than from ground level. Method, equipment and sometimes timing are constrained by more than the glass, and a quote built on pane count will miss most of what makes the job long.
Hurricane season is a discontinuity rather than a trend. One named storm drives salt, organic debris and grit across the entire city at once, and the embedded grit in frames and screens afterwards has to be floated off rather than dragged.
Preservation control and access together set the top of the market. Historic district work carries restrictions on method and equipment, gallery and balcony access rather than ladder placement, and a tourism-driven hospitality book whose scheduling runs around opening hours rather than the working day. Storm season is the other factor, and it should be priced as recurring rather than exceptional.
The French Quarter and the older faubourgs are the reason this is skilled work. Pre-1900 glazing sits in wooden sash on buildings under preservation control, where the method is constrained by more than the glass, and much of it is reached from balconies and galleries rather than from ground level. Elsewhere in the city, soft water and accessible housing make ordinary maintenance genuinely approachable.
OPEN COST ESTIMATOR →2025 annual mean at the Chalmette Vista monitor, 24 E. Chalmette Circle, 12.9 km south of the city (EPA site 22-087-0007).
Largest air release: Chalmette Refining LLC, 500 W ST Bernard HWY (petroleum), 1.4 km outside the city limits, 351,609 lb in 2024.
The Sewerage and Water Board rents hydrant meters in New Orleans only after an application, a notarized guarantor form and a $2,500 deposit for the meter and backflow preventer; potable-water applications need a week's notice. The meter has to stay at the address on record, and a missed monthly reading costs $150.
Sewerage and Water Board of New Orleans: steps to apply for a hydrant meter (2026) · SWBNO hydrant meters page · checked September 2026
New Orleans bans obstructing the flow of water in any gutter, canal, pipe or other drainage conduit, and contractors must promptly remove debris from their jobs, concrete and roofing material included, from storm drains. Violations carry a $500 fine, up to six months in jail, or both.
New Orleans Code §146-501: gutters not to be obstructed · checked September 2026
New Orleans's two landmark commissions (the HDLC and, downtown, the CBD HDLC) must approve construction or alteration in a historic district before it happens. Work done without a certificate of appropriateness has to come back as a retention application with a $500 fee, and work that strays from an approved certificate beyond what staff can sign off costs $250 to retain.
New Orleans Code §84-52: retention applications and fees for work without a certificate · checked September 2026
Loblolly pine and longleaf pine produce the dominant statewide spring contaminant. Peak yellow-pollen pulse late March in the southern half, mid-April in the northern half. Wet-only handling. No scraping, no dry-brushing — drives pollen deeper into glass-surface micro-texture. Heaviest booking-pressure stretch of the year statewide.
Open-Gulf salt aerosol on Cameron Parish and Grand Isle waterfront stock. Brackish-bayou aerosol on Plaquemines, St. Bernard, Lafourche, Terrebonne residential. Wet-rinse-first protocol. Monthly visit frequency standard on high-end coastal and bayou-front residential. Pattern continuous with Mississippi and Alabama Gulf Coast.
Lower Mississippi industrial-and-agricultural runoff contributes a tinted composite residue on New Orleans metro residential and commercial. Faint-organic fingerprint requires extended citric dwell. Compounded by Sewerage and Water Board distribution-system age and occasional discoloration episodes.
New Orleans runs on Sewerage and Water Board of New Orleans lake or reservoir surface water at a hardness Sewerage and Water Board of New Orleans does not publish. The Sewerage and Water Board publishes no hardness figure.
Residential window cleaning in New Orleans typically runs $10–16 per pane or $300–550 for a standard single-story exterior. Preservation control and access together set the top of the market.
New Orleans's drier, frost-free months are February to May and October and November, by NOAA's 1991–2020 normals for the New Orleans Lakefront Airport station, where July brings the most rain. The calendar on this page marks March (after the February 15 bloom) and October (after smoke season). A frost night comes in about half of winters, near January 5.
Sewerage and Water Board of New Orleans publishes neither hardness nor dissolved solids, so rinse one pane and let it dry in sun; a white ring means switch to pure water. The supply is treated with chloramine, which lasts in a bucket and wears deionising resin faster. It draws on surface water at the Carrollton plant.
In New Orleans the dominant residue patterns include mould and algae film on shaded elevations in year-round humidity and hurricane-driven salt spray, grit and organic debris. Humidity never lets the glass dry down.
The French Quarter and the older faubourgs are the reason this is skilled work. Pre-1900 glazing sits in wooden sash on buildings under preservation control, where the method is constrained by more than the glass, and much of it is reached from balconies and galleries rather than from ground level.
Pre-1850 heritage commercial and residential core — substantial wavy-glass single-pane and leaded-fan concentration. Garden District and Marigny / Bywater have their own housing stock and glazing as well.
Just over the Louisiana line