Derby Water Hardness & Quality Report (2026)

Derby, Kansas, in Sedgwick County south of Wichita — a fast-growing Wichita suburb with significant ties to McConnell Air Force Base — receives its municipal water from the City of Derby Public Works, drawing from the Equus Beds Aquifer — the same prolific buried valley groundwater system that supplies the entire Wichita metropolitan area. The Equus Beds Aquifer is one of the most important water resources on the Kansas plains, providing high-yield groundwater from thick Quaternary alluvial deposits buried beneath the Arkansas River valley corridor.

The hard 196 mg/L hardness and TDS of 484 mg/L reflect the Equus Beds Aquifer's characteristic mineral character. The Equus Beds contain thick Quaternary alluvial and glaciofluvial sands and gravels filling buried ancestral Arkansas River channels — sediments composed largely of material eroded from Permian red beds and evaporite formations and Cretaceous carbonate terrain of the upper Arkansas drainage basin in Kansas and Colorado. Water filtering through these calcareous sands and gravels naturally dissolves calcium and magnesium, and contact with Permian Cimarron Formation gypsum and carbonate layers adds sulfate and additional hardness to the regional supply.

At 196 mg/L, Derby's water is hard — standard for the Wichita metro area groundwater supply zone. Scale builds in kettles and coffee machines within weeks, dishwashers benefit from rinse aid, and bathroom fixtures develop calcium rings over time. Water heaters in Derby homes accumulate scale that reduces efficiency without annual maintenance. Descaling appliances every six to eight weeks is the practical cadence. A positive note: the PFAS level of 3.1 ppt is among the lowest in the Kansas dataset — despite Derby's proximity to McConnell AFB, the Equus Beds Aquifer's natural filtration process limits PFAS penetration compared to surface water supplies.