Wasted: Santa Monica building will fertilize plants with human poop from foam toilets

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Santa Monica’s new City Hall East building will use human waste — processed as compost by “foam-flush toilets” — to fertilize plants. Photo by Amy Ta.

KCRW’s new series, “Wasted,” introduces audiences to uncovering neat solutions to the dirty problem of waste. You can listen to more from the two month-long series here.

Solutions to society’s waste problems can be found in even the least glamorous of places, including a public bathroom off the 10 freeway.

It’s part of Santa Monica’s new City Hall East building, designed by Frederick Fisher and Partners, and will open in spring. Its bathroom has “foam-flush” toilets, which use three tablespoons of water per flush instead of the 1.6 gallons that a standard toilet uses. 

“The biggest waste in waste water is the fact we are using fresh water to transport sewage,” says Ed Osann of the Natural Resources Defense Council.

It’s part of what helped City Hall East achieve the elusive sustainability designation of a living building. The water it does use is recycled rainwater.

It might sound clever, but so far it’s been a challenge to get the staff excited about their new toilets.

Amber Richane with the city of Santa Monica says people wonder how they’ll go to the bathroom.  “And you're like, ‘It's a normal toilet. It just has foam in the bowl instead of water.’” 

After someone flushes, the toilet automatically begins to foam at the rim of the bowl, and then oozes down the sides. Richane says the forces of foam and gravity can handle even the messiest waste.

But the foam flush toilets do more than just conserve water. They’re also known as compost toilets, because they prepare human waste for what the designers call “beneficial reuse.”

Beneath the toilets is a compost room, housing six large worm bins lined with wood chips and holding the waste from the toilets. The bugs burrow little holes to help aerate the waste and turn it into compost. Once the pandemic subsides and the toilets are in full use, they’ll require monthly maintenance.

“You open up that black hatch, there's a very long rake, and you rake it until it's smooth like batter, not layered like lasagna,” says Richane.

Then 18-24 months later, the building uses the nutrient-rich compost for their on-site garden. And because it’s an aerobic system that stays ventilated, it does not cause any foul smell.

The design might sound flawless, but compost toilets are still rare. Part of the problem is the price. Santa Monica paid $75 million for this building, and compost toilets cost thousands of dollars each. That cost is especially prohibitive for buildings with existing plumbing, since compost toilets would require ripping that out and starting from scratch.

Then of course, there’s the yuck factor.

“Unless the — you might call it the user experience for want of a better term — is comparable to what we would expect in a public place in a public restroom or … in your own home. … That is a challenge and that should be a design objective,” says Osann.

Lead engineer Julian Parsley works for Buro Happold. He says he likely wouldn’t put a compost toilet in his own home.

“I think I'd have a hard time convincing my family. If it was just me alone, I think I would.”