In which situation would graywater recycling be most beneficial?

Graywater recycling is most beneficial for irrigation and non-potable uses because it allows for the reuse of wastewater generated from household activities such as showering, washing dishes, and laundry. By treating and repurposing graywater for these applications, it reduces the demand on potable water supplies, promotes sustainable water management, and helps conserve valuable fresh water resources.

Using graywater in irrigation not only conserves water but also benefits plants since graywater often contains nutrients that can act as fertilizers. Additionally, non-potable uses like toilet flushing can significantly reduce the overall consumption of clean drinking water, further enhancing water efficiency in a building or site.

The other options do not capitalize on the primary advantages of graywater recycling as effectively. Heavy rainfall does not require recycling since there is an abundance of water; residential cooks do not typically generate enough graywater for beneficial recycling; and heating water supply does not directly align with the intended uses of graywater, which focuses on non-potable applications.