The stainless steel JIC-RS100-B Rainswitch from Jensen Instrument has a 14-inch funnel to collect rain. Once 1/10 of an inch of rain has fallen, the level chamber is filled to the point that the capacitive level switch senses the level and changes state to divert the rainwater to the storm drain system. Once the rain has stopped, the pilot station is reset manually or automatically, and the system returns to normal mode. 626/969-7991; www.rainswitch.com.