I read a "This Old house" article on CNN about routing your washing machine drainage to your yard to water plants.
I live in the desert, Phoenix, Arizona to be exact and have been doing this for over 15 years. I plumbed my washer through the exterior wall with PVC pipe and attached 50 ft of clear flexible tubing, I believe it is 2 inch but could be bigger so I could move it around the yard to water the various plants. It has work exceptionally well. The plants are strong and healthy and it has cut my use of drinking water for plant watering down to zero for plants and trees in my back yard. I use All as my detergent of choice because it does not contain phosphates. I don't know if that actually makes a difference, but phosphates irritate my skin, so figured they probably wouldn't be good for plants either.
I have also plumbed my front bathroom sink the same way, it drains to the side yard where I move the hose once a week to the various plants, they are also doing exceptionally well. If I could figure out a way to do the shower (location is not on an exterior wall) I would be completely set. I monitored this closely to see if shaving cream, toothpaste residue and soap residue would adversely affect the plants. After 15 years, there is no discernable impact, other than the plants are growing at an enviable rate.
However, what we really need is an enlightened city code. When I contacted the City of Phoenix, they told me what I had done violated city code, so I never told them where I lived. Also, we need to improve the City's water codes. Our sewer rates are based on consumption. So even though the 1st and 3rd major consumers of water in my house, laundry and sink are not dumping into the sewer system, I am still being charged the sewer charge for that use.
Both plumbing changes were extremely simple (completed in less than an hour), and the costs for materials (roughly $60 for the washer and $30 for the sink) has been recovered thousands of times over.