May - June 2010
Vol. 73 No. 3


Where there's rain, there's runoff: integrated water management begins at home

If we have a scarcity of water, how can we at the same time have too much stormwater - and what can we do about it?

The federal Environmental Protection Agency views urban runoff as one of the greatest threats to water quality in the country and "one of the most significant reasons that water quality standards are not being met nationwide." Most often runoff comes from rainwater, especially when rain falls on impervious (nonporous) surfaces such as roofs, roadways, driveways, and sidewalks. Other runoff derives from improperly operated watering systems that leave more water on pavement than on gardens, or from illegal discharge from industry or commercial businesses. Whatever the source, runoff almost always carries toxins (from motor oil, chemicals, animal waste), which thus enter storm drains to end up in streams, rivers, bays, and the ocean.

If we can find ways to use that stormwater before it enters the drains, we can turn it from a liability to an asset. That's why rainwater-harvesting rebates and incentives are popping up all around the Bay Area. In San Francisco, Palo Alto, Santa Rosa, Marin, Petaluma, and Scott's Valley, stormwater divisions and water agencies are looking for ways to help residents and customers become more water savvy with rainwater.

One step we can take with the immediate and far-reaching impacts is to focus on stormwater management. While many of us think of stormwater runoff as a municipal matter, it is anything but! Low Impact Development (LID) is a new concept in water management that can be adopted by all sectors: residential, commercial, institutional, industrial, and agricultural. LID considers how to retain the water that falls on a property rather than allowing it to run off.

There are two main strategies:

  • on-site infiltration (letting water soak into the ground);
  • on-site water use (followed by graywater reuse, and on-site infiltration, if possible).

Infiltration can be accomplished by removing as much of your concrete and other impervious surfaces as possible, replacing them with gardens, pebbles, mulch, or pervious pavement. Roots, the top layers of soil, and mulch are great natural filters - why not add gardens to your property? With low-water ("xeriscaped") contoured rain gardens full of native plantings and food crops, you'll help create an appropriate local ecological system in which biodiversity of species can thrive. If you lack ground area for infiltration, consider installing a roof-top garden, a green or living roof. It's yet another way to extend biological corridors and to reduce the urban heat sink.

On-site usage also means capturing and storing rainwater for flushing, clothes-washing, or commercial and industrial applications. With proper filtration, you can also safely use rainwater for drinking and bathing. During the rainy season, unless you have a huge capacity for water storage, it makes most sense for Californians to use rainwater indoors. Then in the dry season, use all the rainwater you've had the capacity to store, supplemented by graywater from your washing machine, shower, or bathroom sink. More and more multifamily dwellings, commercial, and industrial buildings are now being designed with dual plumbing systems and appropriate irrigation systems to capture and use or infiltrate as much water on-site as possible. Cities including Emeryville and San Francisco are proactively working towards ordinances requiring on-site water management.

The benefits of rainwater and graywater harvesting are a reduction in use of energy-intensive potable water as well as the reuse of water in safe and legal ways. Each one of us is responsible for how we use resources.


Learn about installing an appropriate rainwater-harvesting system by visiting Wholly H2o, California's Integrated Water Management Information center.

Always begin your integrated water-management plan with conservation and efficiency. No matter where your water comes from, using it wisely is going to make a large impact in the long run. Conservation means reducing the total amount of water you use, while efficiency means using a quantity of water with care, so that you accomplish more with the same amount of water. Visit Wholly H2o's section on efficiency to learn more about specific actions.