Homeowner Carrie Wassenaar, pictured November 4, 2015, shows off a new 1,320 gallon (5,000 liter) water tank designed to capture storm water during the huge El Nino rainfalls expected in Los Angeles

Officials in drought-stricken Los Angeles want locals to consider installing special cisterns to collect rainwater that would otherwise run off and go to waste.

It hardly rains in southern California, but when it does, sudden and powerful downpours can lead to flooding and landslides—with much of the excess draining into the Pacific Ocean.

As California enters its fifth year of drought ahead of an El Nino weather phenomenon that is forecast to bring heavy rain early next year, Los Angeles on Wednesday unveiled the first pilot site of what it is calling the "StormCatcher Project."

"In the face of a historic drought, Los Angeles is taking action" to save every water drop, said Los Angeles Mayor Eric Garcetti.

The plan is to retrofit homes "to direct rain from the roof into large tanks that can be monitored and controlled electronically," city officials said in a statement.

The new systems has "the potential to turn two million rooftops in LA County into a distributed network of storm-catching sponges," said Gail Farber, head of the county Public Works department.

In partnership with the nonprofit organization TreePeople and a tech firm, the StormCatcher Project will install and evaluate stormwater capture systems at up to 10 homes.

"By combining smart technology with something as ancient as a cistern and as elemental as the landscaping in our yards, we can greatly reduce our demand for potable water and recharge our local water supply," said TreePeople founder Andy Lipkis.

A newly installed "rain garden," part of drought-alleviation measures in Los Angeles, helps storm overflow captured from a residential rooftop filter gradually into the ground and water table rather than allowing it to go down storm sewers to the sea

The first pilot site at a North Hollywood home modified the roof to best catch the water, and includes a 1,320-gallon "smart cistern with cloud-based software that anticipates rain and adjusts settings to prevent overflow and maximize irrigation and infiltration," the statement said.

If successful, city officials hope to approve subsidies to encourage locals to install the systems.

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