Put a bowl in your bathroom sinks. I bought a pretty one from Mexico that replaced my blue plastic, dollar store bowl. Any kind of bowl will do, but now when I walk into the bathroom I get a little happy tingle when I see the bowl. The bowl will catch the running water. Keep a bucket or two in the bathroom so when the bowl fills up you have someplace to put the water. (You can decorate the bucket – if you like) Place a few cheap (dollar store) plastic shoe storage boxes in the bottom of the shower to collect water as you shower. A two minute shower is much more productive if you turn the water off while lathering or shampooing. Turn the water on for ten or twenty seconds to get wet, then wash, then on again to rinse. Empty the shoe box containers into the bucket. (you can straddle the containers or you can soak your feet in the containers as an added benefit)
Now here’s the really cool part – keep the top to the toilet tank off so you can pour the water into the tank when you flush. What you do is flush, then wait a few seconds until the flapper at the bottom of the tank comes down, then compete with the incoming water to refill the tank. You might get a little wet the first time you try it so don’t try it for the first time in your work clothes. You’ll get really good at it – I promise. I used to flush, then close the seat, then put the bucket onto the closed seat, then wait three seconds for the flapper to come down, then pour the water as quickly as I could into the tank to use as little fresh drinking water to flush as possible. If you don’t wait until the flapper is down to add the bucket water then the flapper may not come down.
It takes only an extra minute and, I admit, it looks a little tacky but you can save ten gallons a day per person doing that.
Use plastic 16 ounce cups to catch the water until it gets warm in the sink. Do this because it is an efficient way to wash your face and brush your teeth. The cool water you catch in the first cup can be used for brushing your teeth and the second warm cup for washing your face.
Put tubs in your kitchen sink as well and do the same thing. The faucets can be fitted with tiny lever shutoffs where the screen goes so once you get the water to the temperature you want, turn it off at the lever so you don’t have to adjust it every time. As you all well know gray water can be used for watering outdoor plants and mopping floors, but you’ll collect way more water than that so use it for other things. Toilet flushing is the single biggest water waster in your home.