Which practice involves collecting and reusing rainwater for non-potable purposes?

Rainwater harvesting is a practice specifically focused on collecting and reusing rainwater for non-potable purposes, such as irrigation, landscaping, and flushing toilets. It involves capturing rainwater typically from rooftops or other surfaces and storing it in tanks for later use. This method not only conserves water but also reduces runoff, helping to mitigate flooding and erosion.

Gray water recycling, on the other hand, pertains to the reuse of water that has already been used for domestic purposes, such as from sinks or laundry. Stormwater management refers to the strategies and practices aimed at managing the quantity and quality of stormwater runoff. Flood control encompasses various techniques and structures designed to prevent flooding, which can include levees or drainage systems, but does not specifically deal with the collection and reuse of rainwater. Thus, rainwater harvesting is distinct in its purpose and methodology, making it the correct choice.