When I was a service plumber I used a curb key to turn the water off at the street.
It reaches down through a narrow (3" across) hole and turned the manual valve.
A similar device might work for turning a three way valve that's in a crawlspace.
Something as simple as a 2" pvc pipe with notches in it might work.
Irrigation valves that are between 1/2" to 1" are actually quite reasonably priced.
There is a large bump up in price above that.
If you filter the grey water before distributing it through the valves you
should be able to use these smaller valves.
A tote, filled with mulch and populated with redwrigglers would probably do the job.