New Hampshire runs as five working zones. Manchester and the Merrimack Valley corridor on Manchester Water Works Lake Massabesic-source surface supply. Nashua and the southern NH border-corridor on Pennichuck Corporation surface-and-aquifer-supplemented supply. Concord and the central NH corridor on Concord General Services Penacook Lake-source surface supply. Portsmouth and the Seacoast corridor on Aquarion Water Bellamy Reservoir-source supply with substantial coastal salt-aerosol overlay. The White Mountains and Lakes Region tourism-corridor on mixed municipal and aquifer supplies. Rural New Hampshire well-water through the Granite State backcountry on local aquifer and well-water systems.
HOW IT BREAKS DOWNsoft (Portsmouth, Nashua, Concord); moderately hard to hard by the utility's own description (Dover); 1 of 5 covered cities publishes no figure
Concord and Nashua publish soft, and Portsmouth is soft at the low end of its published range. White Mountains corridor high-elevation UV-accelerated IGU seal degradation is operational wildcard parallel to what Easton Giordano documents for the Colorado Front Range and what Easton covers for the New Mexico mountain corridor. Portsmouth pre-1800 heritage residential among the deepest in northern New England — operationally distinctive concentration. Salt-aerosol overlay on Seacoast corridor commercial-and-residential. Ski-corridor seasonal commercial through Bretton Woods, Cannon, Loon, Waterville Valley, Attitash, Wildcat, Mount Sunapee, Pats Peak, Crotched Mountain, Gunstock. Foliage-season commercial concentration October. Granite State no-sales-tax commercial concentration drives substantial border-corridor retail commercial. Winter exterior work effectively shuts down December through February statewide.
A blended system means hardness moves with the blend. Two addresses on the same utility can read differently, and the same address can read differently across a year, depending on which source is carrying the load that season.
New Hampshire spans 4 hardness bands, which means there is no single answer for the whole state — the method changes as you move across it. Both ends are below.
Tap water is clean enough to be the last thing that touches the glass. Wash with it, rinse with it, squeegee it off, and nothing measurable is left behind when it dries. No distilled rinse, no deionized final pass, no spot-free rinse aid — the mineral load is too low to precipitate anything you would see. The failure mode at this end of the scale is not water chemistry, it is technique: streaks here come from a worn rubber, a dirty edge, or a pass that dried before it was pulled.
Tap water is still fine for most residential glass, with two exceptions worth knowing. Dark glass shows a faint mineral haze that lighter glass hides, and glass that is hot enough to flash the water off before you pull the squeegee will spot regardless of how soft the supply is. On both, a distilled final rinse costs about a dollar a window and removes the variable entirely. Everywhere else at this level, the water is not what is wrong.
This is the band where the water starts writing on the glass. Wash with tap — the surfactant holds the minerals in suspension while you work, so the wash pass is not the problem — then rinse with distilled and pull that. The rinse is the whole intervention: it replaces the mineral-bearing water sitting on the glass with water that has nothing in it to leave. This single change resolves most of the "I cleaned it and it still looks bad" complaints in this range, and it does not require buying a system.
A distilled rinse stops being an improvement and becomes the method. Tap water left to dry on glass at this concentration deposits a visible film within minutes, and the film is cumulative: each cleaning that ends in tap water adds a layer that the next cleaning has to get through first. Glass on a sprinkler line or under a runoff drip needs a maintenance interval, not just a better wash — the deposit is arriving faster than a cleaning schedule built around dust would predict.
Hardest first — the order that matters, because the hard end is where the method has to change. Each figure is the named utility's own published number; cities whose utility publishes none are listed after them, without a band. Within New Hampshire the spread runs from Concord at 9–10 mg/L to Portsmouth at 13–204 mg/L — a difference big enough that the same bottle of cleaner behaves differently in each.
Where New Hampshire's city pages sit in the national city rankings: hardness rank out of 185 cities whose utility publishes a figure, dissolved-solids rank out of 100, the disinfectant each utility reports, and the months each city's cleaning calendar marks for a wash. Rank 1 is the hardest or most mineral-heavy. 2 of these 5 cities use chloramine.
| CITY | HARDNESS RANK | TDS RANK | DISINFECTANT | WASH IN |
|---|---|---|---|---|
| Portsmouth | 152 / 18513–204 mg/L | not ranked | free chlorine | Jul |
| Nashua | 175 / 18520.8 mg/L | not ranked | free chlorine | Jul |
| Concord | 181 / 1859–10 mg/L | not ranked | chloramine | Aug |
| Dover | not ranked | not ranked | free chlorine | Jul |
| Manchester | not ranked | not ranked | ozone + chloramine | Jul |
This page is about New Hampshire's water and nothing else. For how cleaning actually works in New Hampshire across the year — climate, seasonal timing, the local contaminants, the housing stock — see the New Hampshire cleaning guide.
For a figure at your own address rather than your city, the Hard Water Scorer takes a ZIP code. If you run a pure-water system, the TDS diagnostic reads the other end of the same problem.
Each covered city utility's own published figure, taken from its most recent annual water quality report (Consumer Confidence Report) or its water-quality page, read in 2026. A city figure is the one its utility publishes for the service area, as a single number or the range it reports; it is not a reading from any one tap. A state range runs from the lowest to the highest figure published by the utilities we cover in that state, so it brackets those cities rather than describing an average resident. A state where no covered utility publishes a figure shows a planning estimate, labelled as one.
Private wells are outside all of it. A well is whatever the rock under it says, and the only number that describes one is a test of that tap. Have a reading that disagrees with this table? Send it to us — a number that contradicts the table is worth more than one that confirms it.