Wisconsin Statewide Rule

Wisconsin Rainwater Harvesting: Rain Barrels Legal, Downspouts Exempt From Plumbing Code

Few RestrictionsApplies statewide across Wisconsin (2026)

Key Facts

Governing statute: Wis. Stat. 145.01(10)
Rain barrels: Legal, no state permit
Downspout collection: Excluded from plumbing code
Indoor reuse: Needs licensed plumber, backflow
Enforcing agency: Wisconsin DSPS

Last verified: July 31, 2026

Summary

Wisconsin has no statute banning rainwater harvesting. Under Wis. Stat. 145.01(10)(br)1, a rainwater gutter or downspout is expressly excluded from the legal definition of "plumbing" until it discharges into a plumbing system, so a rain barrel or cistern needs no state plumbing permit for outdoor collection.

(a) "Plumbing" means: 1. All piping, fixtures, appliances, equipment, devices, and appurtenances in connection with water supply systems, water distribution systems, wastewater drainage systems, reclaimed water systems, and stormwater use systems... (br) "Plumbing" does not include any of the following: 1. A rainwater gutter or downspout down to the point that it discharges into a plumbing system, a subsoil drain, or a foundation drain.

View official code

Full Breakdown

Collecting rainwater off your roof is legal statewide. Wis. Stat. 145.01(10)(a)1 folds "stormwater use systems" into regulated plumbing, but paragraph (br)1 carves out the gutter and downspout "down to the point that it discharges into a plumbing system." A barrel or cistern fed by a downspout therefore falls outside the Uniform Dwelling and plumbing code (SPS 382-384) that the Department of Safety and Professional Services enforces. Regulation begins only when you pipe collected water indoors for toilet flushing or other nonpotable reuse, which then requires a licensed plumber and code-compliant backflow protection.

Violations & Penalties

Piping harvested rainwater into a home's plumbing for reuse without a licensed plumber or approved backflow protection violates the state plumbing code and can trigger DSPS correction orders, failed inspection, and permit denial.

Frequently Asked Questions

Do I need a permit for a rain barrel in Wisconsin?

No. A downspout-fed rain barrel is excluded from the plumbing definition under Wis. Stat. 145.01(10)(br)1, so no state plumbing permit is required for basic outdoor collection and irrigation.

When does rainwater collection become regulated?

Once collected rainwater is piped indoors as a stormwater use system for reuse such as toilet flushing, it counts as plumbing and must meet SPS 382-384 code, including backflow protection installed by a licensed plumber.

Can I drink harvested rainwater in Wisconsin?

No. Wisconsin treats rainwater as nonpotable. Reuse is limited to non-drinking uses like irrigation and toilet flushing under the state plumbing treatment standards.

Sources

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