Not really.
I collect rainwater here in Sonoma, California. Last time I checked, California was still in the US.
I mean, who wouldn't? The garden shed's roof is about 100sqft. Given our average annual rainfall of 33 inches here at Chez Jake, that's a tick over 2,000 US gallons. Enough to keep the garden off the kitchen watered. Now throw in the water from the roofs of the houses, the barns, the tractor shed, etc, and we've got more than enough water to grow food (meat, too!), even in drought-stricken California. All completely legal.