California Code, Water Code - WAT § 10573

(a) “Developed or developing lands” means lands that have one or more of the characteristics described in subparagraphs (A) to (C), inclusive, of paragraph (4) of subdivision (b) of Section 56375.3 of the Government Code.

(b) “Rain barrel system” is a type of rainwater capture system that does not use electricity or a water pump and is not connected to or reliant on a potable water system.

(c) “Rainwater” means precipitation on any public or private parcel that has not entered an offsite storm drain system or channel, a flood control channel, or any other stream channel, and has not previously been put to beneficial use.

(d) “Rainwater capture system” means a facility designed to capture, retain, and store rainwater flowing off a building rooftop for subsequent onsite use.

(e) “Stormwater” has the same meaning as defined in Section 10561.5.