Storage is going underground. My company manufactures many that are being installed in Washington. They put massive multi compartment storage tanks under parking lots and the such. The one we deal in is called Stormtrap, but there's a few others out there as well. I think the main issue with using the stormwater runoff would be filtering chemicals and sediments out.
There was one just installed where I live, it has a 500k gal. capacity. It is storage for runoff only and is used for irrigation only. I think the answer to issues with runoff water can be solved by reverse osmosis filtration, cheap, prolly not, but it's one answer to water shortage issues.
The other huge issue is the huge energy to run desalination plants. San Diego, and East County are building facilities, and pipelines to reclaim treated sewage and then conveying to existing untreated water reservoirs to be combined and treated to be potable. Reclaiming sewage is much cheaper and requires much less energy as ocean water, because ocean water has much higher total dissolved solids, especially salts.
The other thing would be collecting it all and storing it somewhere. Then what would you do with it? If you sent it to a sewage treatment plant, it would be very expensive to treat and reclaim. You couldn’t send it straight to a water treatment plant, because it’s too dirty. You couldn’t use it for irrigation either without treating. Individually people reclaim rain water successfully for their own irrigation.
Is letting someone's house burn to the ground and doing nothing better than actually starting the house on fire? End result still equals a burnt out house and people out on the street with nothing.
