I'm sure it's only slightly less clean than tap water straight from the facet so I would think you could use that water for a lot of things e.g. plants, watering the lawn, washing the car, laundry, etc.
I wouldn't think it would be safe to drink because of possible bacteria? (think I've read this before) So no giving it to pets for drinking water. Or humans obviously. But otherwise I think it should be fine for most things.