It seems like this summer that Carmel’s city water hasn’t been as soft as usual. Has something changed?

Nothing has changed, but you did pick up on a “summer vs. winter” issue that impacts the way we soften our water.

Here’s the background.

Softening city water is not required by the Environmental Protection Agency but it is an option which Carmel Utilities chooses to perform for its consumers. Softer water is easier on our pipes and has other benefits as well.

The Utility uses the ion exchange softening technique to achieve softer water. And like most residential softeners, each of the Utility softeners must “regenerate” for proper operations. When the demand is higher, more water bypasses the softeners, making the finished water harder than what most residents are accustomed to during the lower demand times – but still softer than other surrounding communities that do not soften.

Carmel Water Utilities operates primarily on two schedules: The HIGH DEMAND summer schedule and the LOWER DEMAND schedule the rest of the year. These schedules do not have designated start or end dates but are based off the weather patterns and usage activities.

The high demand summer schedule, historically, is between June and September each year. During these months, there are more outdoor activities, including lawn irrigation. When the forecast is hot and dry, the irrigation demand increases.

During this high demand summer schedule, the amount of water softening is reduced to ensure that there is adequate supply during the peak hours, as this demand can be three times greater than the normal demand.

The ground water used as the source for the City’s drinking water ranges between 20-32 grains per gallon, or GPG’s. During the lower demand schedule, Utility softening processes improve the average hardness being distributed to between 8-10 GPG’s. But during the summer, that average is between 12-18 GPG’s.

Even when the weather is hot and dry, there is still a reduction in the hardness prior to being distributed. And regardless of what the water is used for – lawn irrigation, showers, coffee in the morning – all drinking water distributed to customers must be compliant with all applicable drinking water regulations.


Our utility department suggests that we change the settings on water softeners at least twice a year, to adjust for the different demands on water. Each water softener is different.  There are dozens, maybe hundreds of different makes and models from the Mercedes version to an old Chevy.  All with different features on how to adjust the settings. One consistent feature: You must adjust the level of softness manually. That process varies from brand to brand. Typically you would increase the softening in the heavy usage summer months, then reduce it when we get into late fall and winter.

Authored by Laura Campbell, Kevin Rider, Jeff Worrell, Tim Hannon, Sue Finkam, Bruce Kimball, Miles Nelson, Anthony Green and Adam Aasen.