For easily 25 years, starting in Denver when my sink trap began to leak and I put a bucket beneath it, then decided to REMOVE the trap rather than repair it, I've been saving and using my kitchen graywater to nourish my crops and Old Roses. This is a 4 gallon hard boiled egg bucket that a friend gives me TONS of.....perfect height to slip beneath the pipe leaving the sink. I keep a 5 gallon bucket with a strong handle on the kitchen floor to dump the contents of the sink bucket into when it starts to get full. Since in much of the world people have to walk great distances to get, then bring home, water for cooking and cleaning, I enjoy taking 5 gallon buckets to dry areas or to thirsty plants like my guava or bananas, as a form of exercise AND mindful awareness of my water use vs. it disappearing unseen down the drain. Saving sink water in these buckets visibly quantifies my water use, as does my 1 gallon, solar-heated Arizona Green Tea jug showers I take daily in the back yard, standing in a tub to catch that gallon to use on my roses. I just swapped out the gnarly old bucket in this pic for a pristine new one to make my low-tech graywater recovery system all perky and Martha Stewarty looking.
I've done this for SO long that when I am in other peoples' homes I probably visibly palpitate as they let the water run and run as they peel a carrot or something, ALL that unknown quantity of precious water slipping down the drain, wasted (in my tightwad gardening mind at least). If you do this, remember two things: sit the bucket in a tray for the INEVITABLE occasional overflow, especially at the beginning when you are learning how a bucket quantifies your water use, and: stuff a used plastic grocery bag into the pipe that leads out of your home to insure sewer gas (methane) not seep into your home as that is the main purpose of the sink trap.
I am sure I will do this the rest of my life unless I end up a doddering old fart too weak to carry buckets of water! John