AZ HB2778

Prohibits homeowners' associations (HOAs) in condominiums and planned communities from banning rainwater harvesting systems designed as water-saving devices.

Allows HOAs to adopt reasonable rules governing aesthetics, dimensions, placement, and external appearance of rainwater harvesting systems, provided such rules do not prevent installation, impair functioning, restrict use, or reduce efficiency.

Defines rainwater harvesting systems to include both active systems (collecting and storing water in cisterns, tanks, or barrels requiring valves or timers) and passive systems (rain gardens and concave earthworks that store water in soil without mechanical access).

Expands Arizona Revised Statutes section 33-1816 to include rainwater harvesting alongside existing solar energy device protections for planned communities.

Entitles any party who substantially prevails in court action against an HOA board for violations of these provisions to recover reasonable attorney fees and costs.