Johnson County has the widest spread of municipal water treatment anywhere in Eastern Iowa. Iowa City softens at the plant down to roughly 3 grains per gallon. North Liberty runs reverse osmosis and nanofiltration. Coralville and Solon do not soften at all. Tiffin is building an RO plant right now. Four towns, four completely different answers — which is why a countywide claim about "Iowa water" is useless here.
| Community | Source | Treated for hardness? | Published hardness |
|---|---|---|---|
| Iowa City | City wells and river-influenced supply, treated at the city plant | Yes — the plant softens | Raw around 300 mg/L (17.5 gpg), softened to roughly 50 mg/L (about 3 gpg) at the plant, per the city's Water Division |
| North Liberty | Jordan and Silurian aquifers | Yes — a 2018 plant using reverse osmosis and nanofiltration | About 5–6 gpg (roughly 85–103 mg/L). When the plant opened the city advised softener owners to dial settings down from 10 grains to 5–6 |
| Coralville | Three aquifer layers — about 50% Jordan (~1,600 ft), 30% Silurian (~500 ft), the rest shallow Pleistocene wells (~100 ft) | No — treatment is aeration, gravity filtration for iron and manganese, then chlorination | None published |
| Solon | Three wells up to 350 ft in the Silurian aquifer | No — the city lists fluoridation and chlorination only | None published; the city does post a Mineral Analysis Report |
| Tiffin | Two wells in two aquifers — Tiffin #3 at 326 ft (Silurian-Devonian) and Tiffin #4 at 1,651 ft (Cambrian-Ordovician), per Iowa DNR | Not yet — an RO treatment plant is under construction, with substantial completion required by September 30, 2026 | None published |
For scale: the USGS calls water above 180 mg/L "very hard," 121–180 "hard," and 61–120 "moderately hard." One grain per gallon equals 17.1 mg/L.
An Iowa City household at roughly 3 grains and a Solon household on unsoftened Silurian water are not in the same market for equipment, and any company quoting them the same system is not paying attention.
In Iowa City, the plant has done most of the work. What is left is a genuine judgment call and often what people actually want is an $800 reverse osmosis system at the kitchen sink for taste and drinking water, not a whole-home softener.
In North Liberty, 5–6 grains is moderately hard — softer than most of Eastern Iowa, still enough to spot glassware and scale a water heater slowly. If you already own a softener there, the city's own guidance was to set it to 5–6 grains rather than 10. A softener set to the wrong number wastes salt and water every single cycle.
In Coralville and Solon, nothing removes hardness before it reaches you. That is the straightforward softener case.
In Tiffin, the answer is changing. The RO plant is due to be substantially complete by September 30, 2026, and a municipal RO plant changes what arrives at your house. We tell Tiffin homeowners to test now, and we will re-test free once the plant is running rather than sizing equipment today for water that may be different next year.
One thing worth knowing if you live in the Solon area: KCRG reported in February 2026, drawing on a USGS study presented to Johnson County in May 2025, that the Silurian aquifer feeding Solon is being drawn down faster than it recharges as the corridor grows. That is a supply story rather than a water-quality story, and it is the county's own utilities and planners who will deal with it — but it is the sort of thing that eventually shapes which wells a town uses, and therefore what comes out of your tap.
Between the towns — out toward Oxford, Shueyville, Hills and the Iowa River bottoms — plenty of households are on private wells, and no utility monitors or reports on any of them.
The Iowa DNR recommends testing a private well every year for bacteria and nitrate, and Iowa's Private Well Grants program covers free county lab testing through your county environmental health office. Iowa State University extension materials note nitrate is odorless and tasteless and that reverse osmosis, distillation and anion exchange remove it, while the CDC notes boiling does not remove chemical contaminants.
If you are buying a rural property here, note that Iowa doesn't require a well water test at sale. If the home has a septic system, most sales need a septic inspection (with some exemptions), and the seller discloses known wells. Your lender or purchase agreement may still call for a water test (your county environmental health office can tell you about any local rules), and the Iowa DNR recommends one before you buy — see our guide for home buyers. Also useful: well water guide, bacteria and coliform, free well testing, well water treatment.
All-in — equipment, installation by a licensed plumbing professional, taxes, lifetime parts warranty.
0% financing; $100 off for military and first responders. See the full cost breakdown and hardness by city.
City pages with local water data: Iowa City, Coralville, North Liberty, Solon, and Tiffin. We also serve Oxford, Swisher, Shueyville, Hills, Lone Tree and the acreages between, plus West Branch just over the Cedar County line.
Given how differently these five towns treat their water, a test at your own tap is worth more here than anywhere else in Eastern Iowa. Ten minutes, real numbers, a written price the same visit — and an honest "you don't need this" when that is the answer. Call or text 319-319-6566, email ryan@kindwaterco.com, or get an instant quote.
It varies more than any county in the region. Iowa City softens from about 17.5 grains raw down to roughly 3 grains at the plant. North Liberty runs about 5–6 grains after its 2018 RO and nanofiltration plant. Coralville and Solon do not soften at all and publish no figure. Tiffin's RO plant is still under construction.
Often not a full one. The city's plant softens to roughly 3 grains per gallon, which is genuinely soft, so many Iowa City homes are best served by an $800 reverse osmosis system at the kitchen sink for taste and drinking water. We test your tap and tell you honestly which applies.
About 5 to 6 grains per gallon. When North Liberty's reverse-osmosis and nanofiltration plant opened in 2018, the city advised residents with softeners to dial settings down from 10 grains to 5–6. A softener set to the old number wastes salt and water on every cycle.
No. Coralville's described treatment is aeration, gravity filtration for iron and manganese removal, then chlorination — no softening step. Its water comes from three aquifer layers: roughly 50% Jordan at about 1,600 feet, 30% Silurian at about 500 feet, and the remainder shallow Pleistocene wells around 100 feet.
Worth considering. Tiffin's reverse osmosis treatment plant is required to be substantially complete by September 30, 2026, and a municipal RO plant changes the water arriving at your house. We test free now, tell you honestly whether to buy or wait, and re-test at no charge once the plant is running.
Every number on this page comes from a public record. Here is where to open each one yourself.
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Kind Water Co is a d/b/a of Zero Cap Investments LLC · 2258 Bison St, Apt B, Marion, IA 52302
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