Place a bucket under the window A/C to catch the water or insert a long hose that reaches your plants. I also keep a big tub ready for downpours to catch the rain water, which I use for plants or to wash my car. My grandmother used to wash our hair with rain water. She claimed it made hair grow. I always had very long hair and can't vouch for the rainwater, but the grass and plants do grow with it.
It never seems to rain enough when I need water for my vegetable garden, so I had rain diverters put on the roof above two doorways and big plastic trash cans below. Rain is then diverted to a the trash can. Aware of critters climbing in and mosquitoes laying eggs there, I cut a hole in a lid (about 2x3 inches) and put the lid on the can upside down, allowing the water to go right into its reservoir. It beats putting #10 cans all around the drip line; I might do that too, though, this year, as the garden has grown.
Save on watering by collecting rain water in containers. Pretty tin buckets make cute 'collectors'. If you have a tin roof, you can place barrels under the eaves to catch rain water and then it can be gathered in watering cans to take where needed. In case of mosquitoes, check with garden centers. There is a tablet to rid water of the larvae but safe for plants.
RE: Save On Watering By Collecting Rain Water
For the larvae, all I do is spray soap water on top of the water - the mosquitoes don't like it and it won't hurt your plants. (05/25/2007)