The Obama administration’s new report on Global Climate Change Impacts in the United States may not seem revolutionary, but to me it is groundbreaking. It’s rare to see a high-profile government report stating quite so categorically that, infrastructurally speaking, the US – and much of the developed world – is in trouble. To quote: “The nation’s drinking water and wastewater infrastructure is aging. In older cities, some buried water mains are over 100 years old and breaks of these lines are a significant problem. Sewer overflows resulting in the discharge of untreated wastewater also occur frequently. Heavier downpours will exacerbate existing problems in many cities, especially where stormwater catchments and sewers are combined. Drinking water and sewer infrastructure is very expensive to install and maintain. Climate change will present a new set of challenges for designing upgrades to the nation’s water delivery and sewage removal infrastructure.” OK, I knew that, but I didn’t know that Obama’s people did.
What do heavier downpours have to do with anything? It’s all about volume. Combine population growth (which produces volume) with the 770 or so US cities that have combined sewer systems that take in stormwater, and you have serious volume problems any time it rains hard. In the US, the report states, “In the United States, the amount of precipitation falling in the heaviest 1 percent of rain events increased by 20 percent in the past century, while total precipitation increased by 7 percent. Over the last century, there was a 50 percent increase in the frequency of days with precipitation over 4 inches in the upper Midwest.” Already sewage overflows are much commoner than you’d think (see the EPA’s Combined Sewer Overflow site for exhaustive detail and a handy Combined Sewer System demographics map, though I’m puzzled by the “approximately 772 cities” – are they guessing?). And they will become commoner still. “Using 2.5 inches of precipitation in one day as the threshold for initiating a combined sewer overflow event, the frequency of these events in Chicago is expected to rise by 50 percent to 120 percent by the end of this century,302 posing further risks to drinking and recreational water quality.” That means that the $55 billion that the EPA estimates is needed to correct existing sewage overflows will be swamped and drowned by a much, much bigger number.
What’s the solution? I gave a talk last night to a packed Café Scientifique in Stockon-on-Tees, and was asked by the extremely engaged and nice audience the same question. “You’re not suggesting we rip out sewer systems and all have composting toilets, are you?” asked one man. No. Tinkering and some retrofitting and people who want to change their toilet systems, by going off-network or installing dry toilets or greywater filters: that’s all one part of the solution. The other is acknowledging the flaws in our existing system, which the Climate Change report has done, and then figuring out how to fund change, sensibly.