Rainwater Harvesting

rain barrel Rainwater harvesting is an ancient practice enjoying a revival. By diverting, capturing and storing rainwater for later use, rainwater harvesting can help reduce demand on the treated water supply while also helping to limit erosion and polluted runoff that can harm our creeks and the bay.

Rain Barrels and Cisterns


Just 1 inch of rain on a 1,000 square-foot roof produces about 600 gallons of runoff. Rain barrel systems can be a great way to harvest some of this water to supplement irrigation needs. They provide naturally good quality water for your plants, and can even be used as a backup supply in the event of an emergency. MMWD offers rebates up to $50 on qualifying rain barrels and cisterns.

Slow It, Spread It, Sink It


Beyond rain barrels, there are other ways to make the most of the water Mother Nature delivers to your property. Getting started is as simple as adding plant-based mulch and compost to your garden. These organic materials help build rich, spongy soil that can better absorb and hold on to water—a natural storage system for winter rains. 

Next, watch how stormwater travels through your property and look for ways to help it slow down, spread out and sink in. Rain gardens are shallow, planted depressions designed to catch and soak up runoff from impervious surfaces such as your roof, driveway or patio. Similarly, swales are shallow channels that help guide stormwater through your property; they may be vegetated or lined with stone, like a dry creek bed. These simple landscape features help to reduce runoff and erosion, filter contaminants and recharge groundwater. They also can provide habitat for wildlife and add interest and beauty to your garden.

10,000 Rain Gardens Project


In 2010, MMWD partnered with the Salmon Protection and Watershed Network (SPAWN) on the 10,000 Rain Gardens Project, a community-based rainwater harvesting pilot program. Visit the project website for rainwater harvesting information and resources. Want to see rainwater harvesting in action? Take a self-guided tour of the project's five public demonstration sites in Marin.