In most cases, no treatment ...
Published by Peter Cartwright, Cartwright Consulting Co. - President
In most cases, no treatment is required. Usually, the graywater is too dilute to injure landscape plants. If the water is to me used for crops that is a different matter, and, depending on what's in the graywater, there may be a health issue.
If drip irrigation is to be used, some filtration may be required to prevent clogging.