Discussion Rainwater Catchment and Use of Greywater

Hi all,
The email below came in response to the one I sent out earlier on rainwater harvesting. I had also sent it to folks on a list of people working at the County of Sonoma level on developing a graywater policy that ideally should bring on incentives (vs. the huge disincentives currently in place) for graywater and then the topic next our group plans on talking about is rainwater/roofwater harvesting. Currently, since the county has no category for rainwater – they technically consider it “graywater”. I had pointed this issue out to the group as an indication of how much catching up we have to do at the county level and was happy to have the folks in SF reply with the following back up!

Anyway, I thought some folks may be interested in this response from an official in San Francisco’s Urban Watershed Management Program!!

Some hope out there…


Hello all,

I work in the San Francisco PUC’s Wastewater Enterprise. I have been following your progress in Sonoma County on greywater with great interest and look forward to attending the next meeting and learning from your efforts. I’m sorry I have been unable to participate thus far!

I wanted to make a few comments about rainwater harvesting, a practice that we are promoting here in San Francisco along with other LID strategies. Rainwater is the most overlooked part of our water portfolio. We are promoting the use of rainwater harvesting for non-potable uses such as toilet flushing, washdown areas, and irrigation. We are working with our Departments of Public Health and Building Inspection to permit rainwater harvesting systems in San Francisco without requiring treatment to potable standards – only a first flush diverter will be required for non-potable uses. Our Department of Public Health has rightly agreed that rainwater is not the most dangerous thing in a person’s toilet. For systems that will involve body contact or drinking water, potable standards still apply.

As you all know, the benefits of rainwater harvesting are numerous:
• Keep relatively clean water out of the combined sewer system and make it available for use

• Reduce the energy and chemicals needed to treat stormwater in San Francisco’s combined sewer and the energy expended transporting water from far away

• Reduce the volume and peak flows of stormwater entering the sewer, thereby reducing flooding and combined sewer overflows

• Reduce the volume of potable water (brought all the way from Hetch Hetchy!) used for non-potable applications such as irrigation, toilet flushing, vehicle washdown, and cooling systems
Tara Hui, mentioned in the article that was sent out, is working with us here at the SFPUC as part of our team to educate residents about rainwater harvesting and do demonstration projects to teach people how to install these systems themselves. We will also be doing a rain barrel giveaway, followed by a rain barrel discount program in partnership with Cole Hardware. Our hope is to expand into ever larger containers – the bigger the cistern, the greater the benefit. But we’re starting with a focus on rain barrels to get people started.

Looking forward to learning more about your greywater efforts,


Hey Graywater group,

I wanted to send you all the following AP story and the announcement of Brad Lancaster’s upcoming talk and book signing for his second volume on Rainwater Harvesting for Drylands.
The first note below is an email that I was just sent from a citizen, which was sent to me to emphasize that fact that as stated officially by the County of Sonoma – “ we currently view rainwater as graywater”!!!
I really am looking forward to unpacking this issue sooner than later – “rainwater as graywater” – really!!! Wow??
I look forward to working with you all on changing that policy perception, as this issue has obviously been addressed by many many other municipalities.

Brock Dolman

Hi David

I added your name to the Graywater/Rainwater Collection Working Group. Attached are some policy references compiled by the Occidental Arts and Ecology Center. I hope Randy Leach and Zach Rounds can help you with your project to plumb rainwater back into the house. As we currently view rainwater as graywater, the only way you’d be able to permit the rainwater source back into the house would be to meet potable standards through treatment of some sort. Since we don’t permit water quality, I’m hoping Zach can help.