East Valley tap water is among the hardest in the country, and hardness is just one of the issues. Gilbert’s arsenic reaches the federal legal limit. Tempe’s PFOS is 750% of the 2029 federal MCL. San Tan Valley’s nitrate sits at 93% of the maximum contaminant level. Hardness itself runs from 13 grains per gallon (gpg) in Gilbert to peaks of 33 in Tempe groundwater blends.
No single technology addresses all of that. The right setup for most East Valley homes is layered: a softener for hardness throughout the house, a carbon stage for chlorine and disinfection byproducts, and an under-sink reverse osmosis system for the contaminants — arsenic, PFAS, nitrate, TDS — that nothing else touches.
The three pages below walk through what each technology does, what it doesn’t, and how they fit together.
Reverse Osmosis Installation
Gilbert arsenic hits the legal limit. Tempe PFAS is 7.5× the 2029 federal limit. No softener or carbon filter touches these. Diagnostic Plumbing installs under-sink RO systems throughout the East Valley — (480) 220-1266.
Water Softener Installation
East Valley hardness hits 25–33 gpg, among the hardest in the country. Diagnostic Plumbing installs, sizes, and plumbs soft-water loops for the entire service area. ROC #327364. (480) 220-1266.
Whole Home Filtration
Whole-home water filtration systems for clean, filtered water at every tap. Addresses East Valley's hard water and sediment. Salt-less options available. Gilbert, Chandler, Mesa. ROC #327364.
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