when the county installed a new road & sidewalks in front if my house, I noticed on the drawings that the sidewalk had a slight slope toward the street so water would drain off into the gutter rather than on my lawn. I asked the engineer if he could change the direction of slope so I could use that water rather than waste it. He said "no" because that was not the standard dictated in the Uniform Building Code. This code is the standard for the entire country. Pervious concrete is a nice feelgood invention, but if you are serious about saving the planet you will have to change the basic rules that have evolved before the environment became a consideration. I wanted to convert my grey water drains so I could use the water to irrigate my lawn; the county rejected my design; It is illegal to use grey water for irrigation in Santa Barbara county.