As part of the exterior remodeling, we added 2 tanks to the house to capture water for yard use. We get our water from the stockholders membership, but we’re on wells that can run low during drought.
Our approach was to drop in a flat 2000 gal tank under the deck as the primary source. We fill this tank with the downspouts from about 1/4 of our roof. It only takes 1-2 rains to fill this tank up.