Gillette Water Hardness & Quality Report (2026)

The City of Gillette Public Works Department operates the water utility serving approximately 33,000 residents in Campbell County, Wyoming, primarily within the city limits and surrounding areas. Water is supplied exclusively from 26 groundwater wells drawing from the Lance-Fox Hills, Fort Union, and Madison aquifers, with no surface water sources or reservoirs. The water undergoes aeration to remove gases and iron, followed by disinfection with chlorine before distribution through the municipal system, with wells pumping directly to the network after processing.

Gillette's water originates from the Powder River Basin watershed in northeastern Wyoming, underlain by Tertiary and Cretaceous sedimentary formations. The Fort Union Formation (Paleocene) provides the primary shallow aquifer with sandstone lenses, while deeper supplies tap the Madison Limestone (Mississippian), a dolomite-rich carbonate. These geological layers yield groundwater with low mineral content, resulting in a characteristically soft supply. Minimal dissolution from limestones and the absence of gypsum or high-calcium rocks keep the water softly mineralized, unlike harder western aquifers.

As a soft water supply, Gillette experiences minimal scale buildup on fixtures, pipes, and appliances, reducing maintenance needs for water heaters, dishwashers, and laundry machines. Soap lathers easily without excess use, and no spotting occurs on glassware. A water softener is not recommended and could unnecessarily strip beneficial minerals. Routine cleaning with vinegar suffices for any light deposits, while iron staining from aquifers may require occasional attention. Water quality meets EPA standards; chlorination ensures microbial safety and aeration addresses natural iron from the wells.