Greywater policies differ state to state. Currently, the best policy is for the state of Arizona. They have greywater guidelines to educate residents on how to build simple, safe, and affordable, greywater irrigation systems. If people follow the guidelines their systems falls under a general permit and is automatically “legal”, that is, the residents don’t have to apply or pay for any permits or inspections. California had the first greywater code in the nation, but it had been very restrictive and usually made it unfeasible for people to afford installing a permitted system. Because of this the vast majority of systems in California are unpermitted. Using data from a study done by the soap industry, Art Ludwig estimates that for every permit given in the past 20 years, there were 8,000 unpermitted systems built. In 2009 California changed it’s code, making it much easier for people to build simple, low cost systems legally. Washing machine systems that do not alter the house plumbing can be built with out a construction permit so long as 12 guidelines are followed. Read more about codes and policies here.