treating street runoff water for garden use

[satx]

In semi-desertic San Antonio TX, I live next to a short, dry natural, dirt ravine that feeds rainwater runoff from the streets in our small residential tract into a small creek that hardly flows between rains, and can be completely dry in summer. I know pumping water out of the creek is not legal, but I figure rainwater through the ravine, pre-creek, is fair game.

What minimal treatment would be recommended for such water held in a tank for watering the yard and plants (not for anything edible)?

For a holding tank, I was thinking of ACQ pressure-treated 4x4s for the walls of an octagonal tank, with a vinyl liner.

comments? suggestions?

 

[LHA]

Before you get into the engineering, double check with the US Army Corp - not your state regulators, who do not have ultimate jusristiction. My understanding of "Waters of the USA" is that any concentrated conveyance is considered to be one and the same with the surface water it feeds.

I think you are only entitled to detain runoff from your property. You can put a cistern under your roof drains. I am fairly certain you can't take water out of a swale without some type of withdrawal permit.

Technically, though, what you are proposing sounds workable. Roadway runoff will be very high in hydrocarbons and grit. The grit will settle in the tank, the HCs shouldn't kill your grass. If they do, they are too expensive to remove for watering grass anyway.