Can I divert my shower and tub drain to yard watering?

My area has had a severe drought for 4 of the last 5 years and watering is not allowed. I don’t care about the grass but I’ve lost lots of privacy plantings that I’ve put in since I bought the house. I’ve read that the outflow from the washing machine can easily be diverted to a hose that runs to the yard – could a plumber design a system that would allow me to flip a switch and have waste water drain to the outside? (Without any kind of sewage/gas backflow?)