The Commons: Slowing the Flow of Storm Water

The Commons: Slowing the Flow of Storm Water

Higher Ground by Jennifer Davis

How to be a more conscientious custodian of the water that runs through our lives

In more than 700 American cities, especially older cities east of the Mississippi, sewer water and storm water share infrastructure, which means that major weather events can all too easily lead to raw effluent escaping into waterways. With global warming creating more-frequent and less-predictable extreme weather events, more and more cities have to deal with this most unfortunate confluence. It should be a call to action both because it’s a serious problem and because individual efforts can combine to make a real difference in the health of our waterways and communities.

The solutions are basic and straightforward: green roofs, rain catchment barrels, permeable pavers, storm water gardens, and bioswales. All these individual efforts help to slow and filter the flow of storm water so it doesn’t overwhelm the system. Done well, storm water can be filtered by plants and absorbed into the ground without ever reaching a treatment plant.

Nate Griswold is an architect, the founder and president of Inhabitect, and an early proponent of green roofs who has installed more than a thousand systems. Griswold explains that green infrastructure demonstrates what’s called “upstream thinking”: managing water on site, mimicking the natural water cycle, rather than depending on remote “downstream” facilities. Not surprisingly, upstream solutions are rapidly gaining traction in cities with aging infrastructure because the costs of downstream solutions are often staggering. The concept is also taking hold more widely in rural, coastal, and desert communities, as well. Millions of square feet of green roofs are now being installed every year, increasing each year by a rate of 10 percent.

A green roof acts as a gigantic sponge, holding water from running off. This requires stronger-than-normal walls and framing to bear the additional weight, so about three-quarters of green roofs are installed in new buildings. Yet green roofs have huge benefits to mitigate the extra costs, even of retrofits. Plants transpire, so water acts as a “force field” to prevent heat from being absorbed into the roof material—reducing dependence on air conditioning. In winter, a green roof can also reduce heat loss from buildings. The plants on green roofs filter particulates out of the air and reduce the urban heat-island effect (the heat bubble rising from massive urban buildings). Green roofs also absorb ultraviolet rays rather than making them bounce around.

There is a deeper, social value, as well. A green roof introduces a Zen zone—a space to breathe—instead of contributing to claustrophobia. Imagine being in a hospital looking out at greenery instead of asphalt or tile. At the new wing of Munson Hospital in Traverse City, Michigan, patients receiving infusions, along with their families and guests, take full advantage of a new green space. Such views have been shown to contribute to healing and wellness.

Easier, intermediate steps can be taken toward green roofs other than adopting green architecture. Rain barrels catch gutter runoff, slowing it down by means of irrigating the garden. A small section of terracing can redirect rain, making the journey to the storm drain a bit longer. Permeable pavers absorb runoff and can also hide an on-site water reservoir. Strategic plantings along driveways and in parking areas become effective storm water gardens. Ditches planted with native plants become bio-swales. Such simple green improvement can dramatically slow and filter runoff, compared with bare driveways and ditches.

Green infrastructure “has triple bottom line benefits,” says Griswold. It improves the value of the real estate, increasing the tax basis while reducing both utility costs for the owners and municipal costs for managing water. Human health, happiness, and productivity improve around green spaces. Birds and butterflies come back. Becoming more conscientious custodians of water as it passes through our daily lives enables us to leave it cleaner than when we received it, while creating more beautiful spaces.

Upstream Thinking for an Infinitely Long Shower

What’s called upstream thinking—managing water on site—now includes what can be a very pleasurable to-do list: creative planting plus clever designs. But it also includes some firm don’ts: Don’t pollute and don’t waste. Two big polluters to look for are hidden plastics, like microbeads in makeup as well as phosphorous in fertilizers, which contributes to harmful algal blooms downstream. Fortunately, green industries have made such polluters easy to avoid. And now even the waste issue is becoming less onerous. For example, if you enjoy taking really long, hot showers, a Swedish firm has developed a recycling shower that uses only about one gallon of water, which gets filtered at the drain and pumped back through. (See

What you can do

If you have a minute:

Think about one way to slow the storm water flow around your home.

If you have an hour:

Research where your home’s water originates and where it drains.

If you have a month or more:

Get involved in enacting local ordinances to promote use of green infrastructure.

If you have another month:

Plant indigenous plants along areas where water collects.

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