By Travis Pritchard / Illustration by Eric Swesey
San Diego's sewage is crappy. It is, literally, full of crap more so than in any other California city, because of how we deal with wastewater.
The vast majority of the water San Diegans uses to flush toilets, take showers or wash dishes eventually finds its way to the Point Loma Wastewater Treatment Plant. This 50-year-old facility, built into the cliffs near the Cabrillo national Monument, can process up to 240 million gallons (roughly four Olympic-size pools) of sewage and wastewater every day. After it's treated, the sewage travels out to sea through a 4.5-mile pipe before being released onto the ocean floor.
Why is it so crappy? San Diego's version of sewage treatment, called primary treatment, involves collecting wastewater in large tanks, settling out the solids, skimming the surface for floating oils and grease, dosing the remaining water with chlorine and then sending it on its way through the ocean pipe. The treatment plant pumps the left-behind solids to the Miramar landfill where it's used as landfill cover.
The federal Clean Water Act mandates that agencies treat sewage to secondary treatment levels. This process utilizes microbes to digest dissolved pollutants, removing them from the wastewater stream. For roughly the past 30 years, however, San Diego has requested and received waivers to bypass this requirement, citing the high cost (around $1.2 billion) associated with retrofitting the cliff-side Cabrillo treatment facility.
It's difficult to be certain how San Diego's inadequate treatment process impacts the local marine environment, as most of the current monitoring is designed to determine whether the water being dumped into the ocean meets the requirements of the waiver, rather than the actual effects on ocean ecosystems.
Fortunately, there is a solution to this crappy crap-treatment. The City of San Diego just voted to move forward with "indirect potable reuse," sometimes known as "toilet to tap," which will divert some wastewater from the Point Loma facility to another facility, where advanced filters and reverse osmosis membranes ensure the water is pristine. The water can then be pumped to reservoirs, where it will undergo more treatment before being sent to local faucets.
If this sounds gross, consider that Las Vegas' treated sewage gets dumped into the Colorado River, one of our primary sources of drinking water, which means San Diegans are already drinking recycled wastewater.
"Toilet to tap" has the potential to reduce the pollution coming from the Point Loma plant and cut the cost of upgrades to $710 million. It will also provide a reliable, local source of water, reducing our reliance on imported water or expensive and controversial desalinated water.
Once-angry conservationists are still red in the face, but now it's because they're flush with excitement.