I like the idea . . . but it seems to me the wall would have to be reinforced like a battleship to hold the weight of all that water. Also, here where we live (I’m just up the road from this kid’s hometown) there is NO rain from about June to October most years. So the captured rain will only last so long. Lastly, if the wall is tall and solid and in your front yard, that’s going to be like living in a fortress. Maybe not something everyone would want.
there is the seasonal issue isnt there
Im down in San Anselmo...not that far from rohnert park.
the local water district...spent an hour....looking for a shut off valve....for a fire hydrant juts down the street.
300K gallons of water were wasted during that hour according to the fire department
the shut off valve was mere inches from the hydrant but no one knew where it was when the hydrant blew.....because....it was underwater....
Id bet competance at that level....is rife in many many areas...