the collection area must be less than 3,000sf, AND
there is no municipal water supply available, AND
they have, or apply for and receive a well permit.
as long as the intended use doesn't conflict with what is allowed on the well permit.
According to the brief published by the State,
even if you have a valid well permit that restricts your water use to domestic uses, this does not include watering a garden or greenhouse.
This Bill is a good start, but we'll see how much of an effect it has. It's pretty specific, and even their FAQ page makes it sound like they're only budging a little bit.