Water filtration and softeners in Johnston, Iowa
Johnston takes its water through Central Iowa Water Works as one of the twelve founding members, and the City of Johnston runs local distribution. It is a member and not one of the system's four producers, so the seasonal nitrate load gets handled before any of it reaches the city.
Water utility: City of Johnston
Role in Central Iowa Water Works: CIWW member
County: Polk County
June 2026 watering ban: Covered by the 8 June 2026 mandatory lawn watering ban
Johnston inside the regional system
When Central Iowa Water Works went operational on 1 January 2025, Johnston was one of the twelve utilities that formed it. The city buys treated water wholesale and owns the mains, the towers, the rate and the customer relationship. Johnston was named in the mandatory watering ban the CIWW board enacted on 8 June 2026.
Johnston households have the same two problems as the rest of the metro, and the two get solved in two different places in the house. Hardness gets treated where the water comes in, with a softener sized off your measured grains per gallon. Nitrate gets treated where you drink, with RO under the kitchen sink. Carbon at the main line improves chlorine taste and odor everywhere in the house and does nothing for either one of those.
I would rather test your water and tell you that you need one system than quote you all three.
Starting from the Johnston report
The City of Johnston publishes an annual Consumer Confidence Report covering the water it buys and distributes. Read that before you talk to anybody about a system. I do not have a Johnston-specific hardness figure I would quote you as fact, and I am not going to invent one to fill the gap.
Order of operations here is the same as everywhere. Read your tap, read the report, then quote one system if one system is what the numbers call for. A softener for scale and appliance life, reverse osmosis for nitrate in what you drink.
Questions we get asked
Who provides water in Johnston?
The City of Johnston distributes it, and Johnston is one of the twelve founding members of Central Iowa Water Works, which wholesales treated water to the city. Johnston is a member of that system and not one of its four producers.
Was Johnston in the 2026 lawn watering ban?
Yes. Johnston was named directly in the Central Iowa Water Works Stage 3 announcement on 8 June 2026.
Can you install both a softener and a reverse osmosis unit in one visit?
Usually yes. The two serve different purposes, a softener at the point of entry and reverse osmosis at the kitchen tap, and they work well together because the RO unit also removes the small amount of sodium the softener adds. Most combined installations finish in a single visit.
Get your Johnston water tested
Johnston buys treated water wholesale, so nitrate is handled upstream and hardness is the thing left on your side of the meter. One visit tells you how much of it you have.