To fix a leaking downspout, first clear debris from the gutter and downspout to resolve clogs. Inspect the downspout for cracks, rust, or loose joints and repair them using waterproof sealant or replacement sections. Ensure the downspout slopes downward at a 1-2 inch angle per foot to prevent pooling. Secure loose brackets with screws or additional hardware. If the leak persists, consider installing an extended downspout or diverter to redirect water away from the foundation.

Leakage in downspouts often stems from clogs, structural damage, or improper alignment. A 2021 HomeAdvisor study found that 60-70% of downspout leaks are caused by blockages, which restrict water flow and create pressure buildup. Structural issues, such as rust or pest damage, account for 20-30% of failures, as reported by the National Association of Home Builders. Proper slope (1-2 inches per foot) is critical to prevent water backup, per the Environmental Protection Agency (EPA), which estimates improper installation leads to 40% of gutter-related foundation problems. Waterproof sealants like silicone or rubber can extend downspout lifespan by up to 10 years, according to the International Association of Home Inspectors. Proactive maintenance, including annual inspections and debris removal, reduces repair costs by 50%, as cited by the American Society of Civil Engineers. Addressing leaks promptly prevents water damage to roofs, walls, and foundations, which could cost $5,000-$15,000 in repairs if ignored, per data from the Insurance Institute for Property Loss Research.