what are storm drains built for
LAâs storm drain system, which was built in the 1930s and 40s to prevent flooding, carries excess water from rain, sprinklers or business activities away from city streets and straight out to the ocean.ere in Los Angeles, the sanitary sewer system and the municipal storm drain system are two completely separate water drainage systems. The sanitary sewer system takes waste water from toilets, showers and sinks and routes it to one of several waste water treatment plants here in Los Angeles.