I keep a plastic Folger’s coffee container beside the kitchen sink. It’s got a handle shape built in to it which makes it easier to carry, and a large opening so you can dump water into it easily. Whenever someone doesn’t drink all their water, rather than pour it down the sink, I just pour it a little to the right inside my Folger’s. When I rinse out someone’s milk glass, the rinse water goes in the Folger’s (milk is good fertilizer for plants anyway). Boiled some eggs for lunch, let water sit til cool, pour in Folger’s.
I keep a large bucket, obtained for free from a bakery; they really do buy their butter in bulk, right beside the back door. When the coffee container is full, I dump it in the bucket, then cart the bucket to the garden at night to water it.
If you have a double sink, put a plastic bucket in the second one for the rinse water for the dishes (if you still wash dishes by hand). Empty the rinse bucket into the outside bucket. If you only have one sink but the bucket on the counter to be your second sink. Even a large mixing bowl will work.
Have to fill a sink (or large container, that’s just easier) with hot water to quickly thaw the evening meat, scoop that water into the outside bucket.
Kids have a kiddie swimming pool? After the week of swimming is over, scoop water into garden. The kids can help with this one.
We currently have a dripping bathtub faucet so I put a large, empty cranberry juice container under it and dump this water in the outside bucket too. Or haul it out the front door for the flowers there.
As a bonus, this is extra motion, aka exercise!