Rainwater Harvesting

Question: Are there any permits required for rainwater harvesting systems on residential properties?

Answer: This will vary based on your local jurisdiction. In general, a cistern can be installed on-grade without a building permit, as long as it is less than 5,000 gallons and not more than two times as high as it is wide. Talk to your local municipality's building department for the most accurate information for your particular property location. 

For more about design guidelines click HERE.

Question: What are the regulations regarding setbacks for cisterns in Marin County?

Answer: Setbacks vary greatly depending on the zoning of each specific property. Unfortunately, due to other areas of focus and budget constraints, the 10,000 Rain Gardens Project staff has not been able to delve deeply into these questions yet. A good place to start this inquiry is with your municipal building department.
Question: Do I need a permit for one 5,000 gallon cistern or per total of 5,000 gallons (i.e.; two 2,500-gallon cisterns, etc.)

Answer: As far as we understand, a permit is required for each 5,000-gallon cistern or larger. So, you can install two 2,500-gallon cisterns without a building permit. When in doubt, contact your municipal building department.

Question: How much does a rainwater harvesting system cost?

Answer:  This depends entirely on the size and type of system, your property's specific characteristics, and whether you will do-it-yourself of hire a professional. Rainwater harvesting with cisterns and tanks tends to cost more than developing your soil and landscape to harvest water in the soil (i.e.; with mulch, native and Mediterranean-adapted low water plants and rain gardens). Changing your landscape to be more of a rainwater harvesting landscape can start out being free (just a shovel, free wood chips from a local tree company, and some elbow grease) and go up from there, depending on how much engineering or professional landscape design you want to incorporate and what materials your design calls for.

Question:  Can I design and install my own rainwater harvesting system?

Answer: Yes, in many instances. Many aspects of a rainwater harvesting system can be installed by a property owner, though there are some guidelines to follow. In some cases, professional services will be required. 

For more about design guidelines click HERE
For a list of local service providers, click HERE. 
For a list of local suppliers, click HERE.
Question: What are the components of a rainwater catchment system?

Answer: Learn more about them HERE.

Question: Are there any rebates, incentives or tax credits available to help me install a rainwater harvesting system?

Answer:Not currently. But do let the Marin Municipal Water District know about your interest in rebates and incentives.

Question: How do I calculate how much rain I could harvest from my roof and other surfaces?

Answer:  Check out our rainwater harvesting calculator HERE to learn how.
Question: Can you discuss low-pressure irrigation used in combination with rainwater harvested in cisterns?

Answer: You can find some of this discussed on this website within the case studies focused on our demonstration projects, in particular, the projects at the Tamalpais Service District Community Center, the Marin Art and Garden Center and the San Anselmo Public Library. Click HERE to view those.

Question: Where can I see examples of rainwater harvesting and water efficient landscapes? 

Answer: There are more and more rainwater harvesting projects sprouting up in Marin County. See our "Self-Guided Tour" page for details on five local demonstration projects you can visit any time.
Cistern at Tamalpais Community Service District Community Center

At Home In Your Watershed

Question: What is a watershed?

Answer: A watershed is a geographic area draining to a common point. Your property is located in one or more watersheds. Within your property there are sub-watersheds influenced by topography, vegetation, soils, hardscaping, structures and surrounding properties. In a healthy watershed, topographical micro variations, vegetation and mulch help to catch, slow and release water into the soil where it can infiltrate or be used by the plants. Variations in topography hold water and provide direction to flowing water.


Click on image to view larger.
Question: How do my property and actions relate to my watershed and neighbors?

Answer: In our developed landscapes we have altered the water cycle with a dramatic increase of impervious surfaces (roofs, roads, parking lots, etc.), extensive grading to promote quick drainage, and the influx of non-native vegetation, especially turf grass. these alterations lead to changes in the volume and velocity of stormwater rushing for the drains, as well as the water quality in our streams as pollutants and sediments are picked up and carried into them. Graphic at right shows how development impacts the water cycle. Click HERE to learn more.

Stormwater run-off in Marin County flows to stormwater drains that connect with creeks and streams leading to the bay. Along the way, it picks up all kinds of pollutants, ranging from gasoline and oil, to heavy metals discharged from our vehicle brakes and tires, and from fertilizers and pesticides to animal feces and trash. This untreated stormwater contaminates our waterways. Retaining as much stormwater run-off as possible on an individual property reduces this impact.

For more information about watersheds, visit the Occidental Arts and Ecology Center's WATER Institute HERE.