Mount Prospect, IL Landscaping Rules: Rainwater Harvesting (2026)

Rainwater collection in the Village of Mount Prospect is regulated as a permitted obstruction in the zoning chapter, § 14.319. The permitted obstructions table allows a maximum of four rain barrels per lot, up to 55 gallons in size each, subject to the requirements in subsection C of that section. The table marks barrels as permitted in required yards.

Subsection C.1 sets the build standards. Rain barrels located in exterior side yards must be screened via landscaped hedge. Every rain barrel must be equipped with a screen to prevent insect nesting, and must provide an overflow system to direct excess rainwater away from the primary building structure. The insect screen is aimed at mosquito breeding, and the overflow rule protects the house from water that a full barrel cannot hold.

Rain barrels get lighter treatment than most other yard structures. Subsection B.2 states that a building permit is not required for rain barrels, along with outdoor storage cabinets, basketball standards, decorative outdoor structures, arbors and trellises. Subsection B.1 exempts rain barrels from the impervious surface and floor area ratio requirements that apply to other permitted obstructions. Subsection B.3 adds that listed obstructions do not contribute to the total number of accessory structures permitted per lot under § 14.306.

The practical result in the Village of Mount Prospect is a permit-free setup with a hard ceiling on scale: four barrels, 55 gallons each. Larger tanks, cisterns or underground storage are not listed in the § 14.319 table, so they fall outside this allowance and are not authorized by it.