Monroe Water Hardness & Quality Report (2026)

Monroe, Michigan, in Monroe County — the Monroe County seat on the River Raisin at the western shore of Lake Erie, historically significant for the Battle of the River Raisin (1813) — the bloodiest American defeat in the War of 1812 — and as the birthplace of General George Armstrong Custer — receives its municipal water from the Monroe Board of Water and Light (BWL), which draws from the River Raisin intake or the Lake Erie shoreline intake in Monroe County.

The very hard 234 mg/L hardness and high TDS of 606 mg/L reflect the River Raisin watershed's extreme Silurian-Devonian carbonate geology. The River Raisin drains southeast Michigan's Erie Till Plain — the most carbonate-rich glaciated landscape in Michigan. The bedrock underlying Monroe County includes the Silurian Salina Group (thick evaporite sequence — gypsum, anhydrite, and salt interbedded with dolomite), the Silurian Niagara Dolomite, and the Devonian Detroit River Group (dolomite and evaporite). The Salina Group evaporite dissolution contributes extreme sulfate and calcium, while the Niagara Dolomite adds carbonate hardness — together producing the exceptionally high TDS (606 mg/L) and very hard supply characteristic of the River Raisin watershed.

At 234 mg/L with TDS 606 mg/L, Monroe's water is very hard. Scale forms very rapidly on appliances and fixtures. A whole-house water softener is strongly recommended, and kitchen reverse osmosis filtration is advisable given the elevated TDS. The PFAS level of 12.9 ppt is very high and warrants a certified reverse osmosis drinking water filter — the River Raisin corridor's industrial legacy (Ford Motor Company's Monroe assembly operations, Monroe County auto parts manufacturing), and southeast Michigan's defense-industrial PFAS complex contribute to the extreme reading.