Which states limit how much rainwater you can store?

The two states with a gallon limit

Of the 50 states and DC, two set a gallon limit on rooftop rain storage for an ordinary household. Colorado: Most households may use rain barrels: a maximum of two rain barrels with a combined storage of 110 gallons or less per household, rooftop runoff only, used outdoors on the same property (HB16-1005). Larger rooftop collection only for qualifying well-permit holders (SB09-080) or pilot projects (HB09-1129). Utah: Up to 2 covered containers of max 100 gal each with no registration; with free registration at the Utah Division of Water Rights, total storage up to 2,500 gal. Use limited to the same parcel where captured.

Colorado checked 2026-11-06; Utah checked 2026-11-06 against the Division of Water Rights. Other states' entries on the city pages are marked with how recently they were checked.

Does the cap actually bind?

Mostly not. In 6 of the 120 Colorado and Utah cities covered, the useful tank size is above the legal limit and the city page recommends the largest legal size instead. They are Pueblo, CO, Grand Junction, CO, Montrose, CO, Durango, CO, Cañon City, CO, Fruita, CO. In Utah the 2,500-gallon registered limit covers every city, but 28 of 67 Utah cities have a useful size above the 200 gallons allowed without registering, so registering (it is free) is the step to take there.

Everywhere else

No other state sets a household gallon cap in the sources checked so far, but that is not the same as no rules. Several states regulate rainwater used indoors or for drinking through the plumbing code, and cities and HOAs can restrict where a tank sits; Texas, for one, bars HOAs from banning rain barrels outright. Before building anything large, check with your state water agency and local building department.

Related: Barrel or cistern? · Rain in the wrong season.