Lakeside communities are finding that traditional septics contribute an unacceptable loading of phosphates and nitrogen. Although there are remedies, nobody seems to be using one inexpensive remedy: add a calcium-carbonate-rich leaching field.
Which raises another point: Where does he drain his sink, shower, and clothes washer graywater?
Usually if you don’t have a working commode you often don’t have a sink or shower either.
That said I’ve seen clothes washers and kitchen sink drain directly onto a lawn with no ill effects. The lawn was thickest where they drained.
Oh and you said “greywater” which infers you are an RVer ?