We reuse as much water as possible, though different shades of "grey" get sent to different purposes. Little drips from rinsing your fingers or a dish go into a bucket under the faucet and out to the vegetable garden ... a few suds are fine but not a lot ... around 6 gallons per day. Bubbly dishwater goes onto the leaves of our hemlock bush, which has been waging a winning battle with wooly monmouth as the bubbles kill the larvae without adding poisons ... around 1-2 gallons per day. Just be sure to wipe your greasy pots with a peice of scrap paper to remove as much grease as possible before washing as too much grease will damage your plants.
Boiled water from cooking (pasta, veggies, etc.) goes into a pot with a lid until it cools in the winter (you paid to heat it ... might as well let the heat saturate into your house) and in the summer it immediately goes outside onto the brick or gravel walkway to kill weeds and ants ... around a gallon a day. Water that was used to rinse uncooked meat or anything else too questionable to use to water our food supply gets dumped on the ornamental flowers and shrubs ... around another gallon per day.
Our washing machine gets diverted out to the apple trees in the summer, but we use low levels of non-phosphate detergent and few added chemicals ... around 13 loads per week. We're waiting for low-phosphate automatic dishwasher detergent to become available to do the same for the dishwasher. I'm just waiting for an excuse to rip into the walls and add pipes to divert shower/bathwater from the bathrooms to the garden as well as that's all good decent greywater that could be used for irrigation, but unfortuantely right now everything ties into the toilet pipework and it's a major demo project. I tried putting a bucket in to save the water, but it's just too darn heavy to lift! Even tightwads have their limits!