Clarksville water runs 78 to 132 mg/L hard, shaded walls grow mildew through humid summers, and farm fields send dust in concentrated seasonal bursts.
Clarksville's water is moderately hard with enough alkalinity to hold its pH up, the ordinary scale-forming kind, so rinse water left to dry leaves light spots. Shaded walls grow mildew through humid summers and farm fields send dust in seasonal bursts; June and August to October are the best months. The military base keeps move-in and move-out work coming year-round rather than in one season, and a single-story exterior runs $200 to $380.
Clarksville Gas and Water publishes a running average of 97 mg/L across a 78 to 132 span, and pairs it with an alkalinity of 74 and a pH just under 8. That combination — moderate mineral content with enough buffering to hold pH high — is the ordinary scale-forming case, and it rewards a fast blade and a dry detail rather than any change of chemistry. One caveat the operator leaves open: a footnote about calcium measurement makes it unclear whether the published number is the total or only the calcium share, and if it is the latter the real figure is somewhat higher.
| Hardness | 78–132 mg/L as CaCO₃ No band label published; 97 mg/L average sits in the moderately-hard band. |
|---|---|
| pH | 7.9 (range 7–8.4) |
| Alkalinity | 74 mg/L as CaCO₃ (range 52–109) |
| Iron | 0.018 mg/L (range 0–0.1) |
| Manganese | 0.01 mg/L (range 0–0.04) |
| Sodium | 8.66 mg/L |
| Disinfectant | free chlorine |
| Source and treatment | The Cumberland River — the supply is entirely surface water, treated at the Clarksville Water Treatment Plant, whose source is rated reasonably susceptible under the state Source Water Assessment Program · Microfiltration through hollow-fibre membranes with a 0.1 micron pore size, a direct filtration process, with fluoridation and a chlorine residual · No softening step. |
Not in the report: corrosion index, chloride and total dissolved solids.
SOURCE · Clarksville Gas and Water, Water Quality Characteristics table (2025 operating-data averages) at clarksvilletn.gov read with the 2025 Annual Drinking Water Quality Report (clarksvilletn.gov) · How we source these numbers
Humidity runs the residential cycle from March into November, keeping mildew active on shaded and north-facing elevations that need roughly double the frequency of the sunny side. Agricultural dust arrives in short heavy bursts at land preparation and harvest rather than steadily. Military rotation spreads turnover work across the year instead of concentrating it into a summer window, which is the opposite of a university town and makes the workflow steadier.
TENNESSEE SEASON BY SEASON →Clarksville draws from the Cumberland — a working navigable river rather than a protected reservoir. The utility's own table puts hardness at 97 mg/L on average, 78 to 132 — and Tennessee's format is known to carry hardness under a Miscellaneous heading rather than with the secondary standards, so a search that checks only the usual table will miss it. A second trap: one Tennessee operator labels calcium-only hardness as hardness. Above ground the army post dominates, with turnover that runs on rotation rather than a calendar.
Clarksville Gas and Water keeps a standing characteristics table separate from its annual report, refreshed with each year's operating averages, which makes this one of the easier Tennessee systems to check before quoting a job. The 2025 figures give hardness at 97 mg/L across a 78 to 132 range with alkalinity at 74 and pH at 7.9; the 2024 table read 103 across 80 to 126, so the supply is steady from one year to the next rather than swinging with conditions.
The utility's own Water Quality Characteristics table puts hardness at 97 mg/L on average, 78 to 132 across 2025, and finding it takes knowing where Tennessee utilities put the figure.
The Tennessee reporting format carries hardness under a heading labelled Miscellaneous rather than alongside the secondary standards where most states put it.
That was established by reading another Tennessee system's published table, where the secondary-standards section held chloride, sulfate, total dissolved solids and pH but no hardness, while the hardness row sat two tables further down beside sodium, alkalinity, temperature and the Langelier index.
So a search that checks the secondary table and concludes Tennessee does not publish will be wrong. Grep the Miscellaneous heading instead.
There is a second trap in the same state. One Tennessee operator publishes what it labels hardness but reports only the calcium fraction, with no magnesium given anywhere — so the true total is higher and the operator never states it.
A figure labelled hardness in this state therefore needs checking for whether it is total or calcium-only before it is used, which is a step most published numbers do not survive.
Above ground the army post is the dominant economic fact and it is unusual in scale for a city this size, generating a very large rental and service economy with high turnover.
That turnover is frequent rather than seasonal, because military rotation does not follow an academic calendar, which gives this market a steadier flow of change-of-occupancy work than a university town gets.
Humid Tennessee summers keep shaded elevations damp enough that mildew in frames and glazing channels is routine, and the mild winter makes the working season long.
Tobacco and row-crop ground at the edges of the city puts field dust into the air in concentrated bursts at land preparation and harvest rather than accumulating steadily.
The riverfront warehouse fabric is the city's distinctive commercial glazing — large original openings in heavy masonry, under continuing reuse.
The base economy is the structural feature of this market, generating steady change-of-occupancy volume that does not cluster into one season — a real advantage over a university town. That work prices on condition rather than area. Humidity raises return frequency across the residential book. The southern subdivisions price on route density. Riverfront commercial prices on access and original fabric.
Suburban glass is manageable through a long season and the supply is unlikely to be the obstacle. Organic film is the thing that catches people — established mildew needs a mild detergent and dwell time rather than pressure, and scrubbing damp growth drags grit across the surface. Change-of-occupancy work on the rental stock is a recovery job rather than maintenance and should be scoped as one. Riverfront warehouse glazing is original, large and awkward.
OPEN COST ESTIMATOR →2025 annual mean at the Clarksville monitor, 1200 W Creek Coyote Trail, Clarksville, TN 37042, 6.1 km north-west of the city (EPA site 47-125-2001).
Largest air release: Nyrstar Clarksville Inc, 1800 Zinc Plant RD (metal mining), 1.6 km outside the city limits, 200,156 lb in 2024.
Clarksville makes drawing any water from a city fire hydrant, or tampering with one, unlawful for everyone outside the fire department unless the city engineer has approved it in writing beforehand.
Clarksville Code §10-216: fire hydrants, tampering prohibited · checked September 2026
Clarksville prohibits all non-storm water discharges into public or private storm drainage systems, apart from an allowable list that the director of streets can strike for any source found to pollute.
Clarksville Code §12-309: non-storm water discharges · checked September 2026
No building permit for construction, alteration or extension in a Clarksville historic zone issues until the application, with exterior plans and elevations, has gone before the Regional Historic Zoning Commission, which judges exterior design, texture, materials and color against neighbouring buildings and issues a certificate of appropriateness. The building official then inspects the work against that certificate.
Clarksville Zoning Ordinance §9.3: historic overlay district · checked September 2026
Memphis Midtown and shaded inner-city stock through Nashville and Chattanooga show heavy mold-and-mildew bloom on window frames and silicone bead. Hypochlorite or quaternary-ammonium pre-treatment.
Faint organic-tinted residue from upstream algal-bloom activity in the Cumberland during low-flow stretches. Slightly extended citric dwell handles the composite.
Clarksville Gas and Water publishes a running average of 97 mg/L across a 78 to 132 span, and pairs it with an alkalinity of 74 and a pH just under 8. That combination — moderate mineral content with enough buffering to hold pH high — is the ordinary scale-forming case, and it rewards a fast blade and a dry detail rather than any change of chemistry.
Residential window cleaning in Clarksville typically runs $7–12 per pane or $200–380 for a standard single-story exterior. The base economy is the structural feature of this market, generating steady change-of-occupancy volume that does not cluster into one season — a real advantage over a university town.
Clarksville's drier, frost-free months are June and August to October, by NOAA's 1991–2020 normals for the Clarksville Outlaw Airport station. The calendar on this page marks June (after the April 3 bloom) and October (after smoke season and before frost). Frost nights usually run from October 28 to April 6.
Not as the final rinse: Clarksville Gas and Water publishes hardness of 78–132 mg/L, enough to spot as it dries, so finish with pure water. Water left to dry leaves mineral scale; fresh spots lift with a mild acid. It draws on the Cumberland River — the supply is entirely surface water.
In Clarksville the dominant residue patterns include mildew on shaded elevations through humid summers and agricultural field dust in concentrated seasonal bursts. Humidity runs the residential cycle from March into November, keeping mildew active on shaded and north-facing elevations that need roughly double the frequency of the sunny side.
Suburban glass is manageable through a long season and the supply is unlikely to be the obstacle. Organic film is the thing that catches people — established mildew needs a mild detergent and dwell time rather than pressure, and scrubbing damp growth drags grit across the surface.
The historic commercial core above the river, late 19th and early 20th-century frontage with original upper sash over reworked shopfronts. Two eras per elevation. Austin Peay State University and The riverfront and tobacco warehouses have their own housing stock and glazing as well.
Just over the Tennessee line