Rexburg Water Hardness & Quality Report (2026)

Rexburg, Idaho, the Madison County seat — a major southeast Idaho Snake River Plain community (Rexburg is the Madison County seat — a significant southeast Idaho community and one of the most important upper Snake River Valley communities; Rexburg is dominated by Brigham Young University–Idaho (BYU–Idaho — a major Church of Jesus Christ of Latter-day Saints university; BYU-Idaho (formerly Ricks College) was elevated to a 4-year university in 2001 and has grown enormously since, becoming one of the largest LDS Church-affiliated universities; BYU-Idaho students now make up the majority of Rexburg's total population, making Rexburg one of the most college-dominated cities in the United States)), a diverse Madison County community with a predominantly LDS Church-affiliated and university student population (Rexburg has one of the highest percentages of members of the Church of Jesus Christ of Latter-day Saints of any community in the United States), adjacent to St. Anthony and Idaho Falls in the southeast Idaho corridor — draws its municipal water supply from the Eastern Snake River Plain Aquifer via the City of Rexburg Water Division. Water hardness in Rexburg measures 90.5 mg/L — classified as moderately hard.

Rexburg's moderate hardness reflects the southeast Idaho Madison County Snake River Plain volcanic aquifer's moderate character. The ESRPA at Rexburg draws from Quaternary Snake River basalt (calcareous-moderate). Rexburg Water Division treatment produces the moderate 90.5 mg/L.

At 90.5 mg/L, Rexburg residents encounter light scale accumulation. City of Rexburg Water Division consistently delivers water meeting all Idaho DEQ and EPA Safe Drinking Water Act requirements.