St. Louis County, MN Water Use Rules: Recycled Water Rules (2026)

St. 2, List of Adopted Standards, sets the local rules for wastewater and graywater systems, amending Minnesota Rules Chapter 7080. 2240 by adding a county-specific subpart covering graywater recycle and re-use designs that fall outside the state's Type I and Type II graywater categories. Any property owner or installer proposing such a system must obtain an Operating Permit from the county's Environmental Services department before it can be used. The ordinance sets a minimum design floor: the system must demonstrate an acceptable treatment component and must not discharge graywater to the ground surface, closing off simple untreated surface disposal as an option.

The county also directly addresses seasonal reuse, most commonly lawn or garden irrigation, which cannot function through a Minnesota winter. Because these uses are seasonal, the ordinance requires that the residential SSTS be sized to handle the full graywater flow during the periods when the graywater system itself cannot operate, so the primary septic system must be able to absorb 100 percent of household graywater during freeze months rather than relying on the recycling system as backup capacity. Two related plumbing limits sit in the same adopted-standards list: item S caps the building sewer for a graywater system at no more than two inches in diameter, and items T and U bar garbage grinders and grinder pumps from being connected to the drainage system feeding a graywater or SSTS unit.

Together these provisions mean a homeowner cannot simply plumb a garden greywater line without county review; the design has to be submitted, evaluated against the treatment and no-surface-discharge standards, and permitted before installation.