To become a greywater installer, you need a combination of ecological landscaping/permaculture training and basic plumbing skills. There are many ecological landscaping training opportunities from Green Garden programs, Bay Friendly Landscaping, and others. For related skills, many excellent permaculture trainings are offered across the country, like at the Occidental Arts and Ecology Center. Community colleges and trade schools offer classes in basic plumbing skills. Hands-on experience and mentors are important, too. Greywater Action teaches a 5 day course for people wanting to be greywater installers.