That's my girl. To hell with Tyranny!I might just not worry about codes and let them try to catch me.
The biggest question would be how to get the water from the diverter outside the house and to somewhere where it would be useful. How do I find an "eco-plumber" who might have an interest in a project like this?
There are many talented and hungry people. Maybe start at a nursery that have younger owners that are into alternative designs. Here, the Bullock brothers are just one Island over.
Can you access the plumbing in the basement?
Eric