Australia’s Rainwater Cisterns Inspire TreePeople’s Lipkis

Andy Lipkis

Andy Lipkis: Things are changing day to day. Whatever you heard was fact in Los Angeles, even a year ago, is no longer. My goals today are to help us understand that a new, resilient, local water supply is not only possible—it’s now beginning to happen, even at DWP, at LA County Public Works Flood Control, and at LA City Sanitation.

I want to get into how trees and land are used to capture, clean, and hold water, and how we lose it, so we understand the fundamentals about why we need permeable, living soil; how we can biomimic those functions to create a very resilient city without having to unpave everything, but unpaving as much as we can; how that’s happening; how they did it rapidly in Australia, dealing with the kinds of issues that are coming straight at us very fast; and how we can do it here. 

Our natural infrastructure works in a way that we probably forgot and need to remember. Take a very large oak tree, with a canopy that is 100 feet in diameter. What happens underneath is what’s really important. Over several hundred years, the soil built up and created an incredible space that is a habitat. Most oaks have at least 300 species of critter—from rodents to bugs to microorganisms—living in the tree and especially in the soil. Together, they are an ecosystem that is our life-support system. 

That space under a tree is not just habitat. It is a sponge. It is a tank, as is the canopy. It captures the first tenth of an inch of rainfall without ever releasing it. It slows and catches the rain, then drops it in to the sponge that is in the root zone. Water flowing across the surface flows into that sponge and it picks up pollutants. The critters work together to clean it. Then, because the area is really permeable, that water makes its way down to the aquifer. 

The volume of that space is what’s significant. According to the US Forest Service, a tree with a canopy100 feet in diameter has a root-zone sponge five-feet-deep that has the capacity to hold 57,000 liquid gallons of stormwater in a 12-inch flash flood—without it running downstream as a flood. The question is: What happens when we lose the tree, and what do we replace it with? It does stormwater capture, storage tank, flood control, water quality, and all kinds of things. When we lose the tree, we lose all those services. We lose the water, we lose the habitat, and we potentially lose our lives in a drought.

We replaced it with hardscape and separate bureaucracies: a flood control system, stormwater protection system, and water supply system —all these different bureaucracies that never talked to each other again like the tree talked to itself. We created separate infrastructure systems that all hold high costs, some of them with conflicting services. This has delivered us to the point where we have very expensive and vulnerable infrastructure with a public unwilling and unable to pay what it takes to get it up to shape to protect us from coming severe weather.

All climate scientists across the world pointed to Australia as one of the early victims of severe weather and climate change, experiencing hotter hots, wetter wets, and drier dries. They just came through a 12-year historic drought that finished about two and half years ago. When that happened, they were out of water. They’re a fairly dry place anyhow. But they biomimicked the tree and got people to change radically. I’m telling this story because we could emulate it fairly quickly. 

Before the drought, I observed Australians harvesting rainwater out in the countryside. During the drought, I saw all kinds of changes happening in their cities. For those of you who haven’t been in Australia, the cities don’t look any different than ours. In fact, most of them look better. Most condos and homes today have signs on them saying they capture rainwater. They installed cistern tanks galore, which were heavily discounted so they were easy for people to get. A 1,000-gallon one was the minimum size installed. They had tanks to capture 1,000, 5,000, and 20,000 gallons per house. There was an online center where you could size your roof, size your tank, get your rebate from your water district, choose your installer, and get it installed. 

Today, 45 percent of the homes have rainwater harvesting systems in the City of Adelaide, which has the weather most identical to Southern California. In Brisbane, it’s 30 percent. You can’t build, renovate, or make a change to a house now in Sydney without being required to put in a major cistern as part of your water supply. 

During that drought, in a city like Brisbane, water use started at 80 gallons per-person-per-day. It dropped to 33 and hasn’t risen above 40 gallons per day since the drought ended. They more than doubled or tripled their water supply, first by capturing the rain, and then by radically conserving. How did this behavior change? How did residential users become such thrifty managers of the water? Through owning cisterns, they had their own rainwater “bank account.” When you’ve got your cash in your hands, visible, you spend it very differently. When you think it is your life support system, you spend it differently, and that is exactly what happened with residents and their water. That’s how they made it through. 

Ten and a half years into the drought, when they got truly scared, they started building desal plants. By the time the drought was over, none of these were finished. Afterward, Sydney’s plant came online, produced abundant water, and they couldn’t sell a drop. It was mothballed and sold. If we want to talk about drought resilience and a fast—sustainable—response, we should learn from Australia. 

TreePeople has committed itself to helping facilitate this: catalyzing a rapid shift to local water supply and climate resilience in Los Angeles. We’ve set a goal of 50 percent local water. We believe at least 30 percent can be done very quickly with rainwater. With all the other things—groundwater recharge and cleaning up the groundwater, recycling local water—we can hit that target. Santa Monica has a goal of 100 percent local water by 2020. TreePeople, NRDC, and Heal the Bay are working with them to help get there. TreePeople is holding workshops to train people—so that more and more people unpave their yards and neighborhoods, plant trees, install tanks and harvest rain. 

We need, however, a lot of policy support to take it to scale. The good news, just this year, is that DWP, working with TreePeople, got MWD to give a $75-per-rain-barrel rebate. As of now, you can get rain barrels for $10 a piece. But those are tiny—virtually thimbles—even though they’re good starter drugs for rainwater harvesting. A ambitious neighbor of mine gathered all the 300-gallon barrels he could. He’s now got 5,000 gallons of storage. It’s not elegant, but he’s doing it. He’s got abundant water. He wants security, he wants to grow his food, and he never runs out of water.

Probably a thought on your mind is, “It doesn’t rain here.” But it does rain. Last year, the driest calendar year in history, it still rained 3.6 inches. The City of LA throws away at least 3.8 billion gallons per inch of rainfall as runoff. Last month, when it rained 4 inches in one week during that storm, we threw away 13 billion gallons of water. We threw away 3.5 thousand gallons per person, for every one of the 4 million residents of the city. In the driest year in recorded history, we had a lot of water that we could have captured if we built a system like this.

We can manufacture cistern fences that go in between houses and hold 5,000 gallons per fence line 100 feet long, made of recycled plastic. I happened to invent one, but LA’s design community could do better. DWP would like to see us get these fences manufactured locally. There’s a 216,000-gallon underground cistern right in TreePeople’s headquarters at the dead-center heart of Los Angeles—Coldwater and Mulholland. In our last local rainstorm, it captured 81,000 gallons of water.