GREEN INFRASTRUCTURE

Partnering with large and small property owners to reduce impermeable surface and improve groundwater infiltration.

PROJECT

Westside Water Resources is building rainwater catchment systems that reconnect residential and commercial rooftops to the hydrological cycle by diverting runoff from San Francisco’s combined sewer system.

Case study systems are both completed and under construction across the Sunset, with a fully operating system supplying irrigation and groundwater recharge at the Far Out West Community Garden.

WWR targets 15-20 unit bundles of single family homes (totaling ½ acre of impermeable surface) across San Francisco as well as larger commercial and residential properties with at least ½ acre of convertible impermeable surface.

Rooftops are coated with an NSF certified coating to ensure that water infiltrated into the aquifer is of potable quality.

THE PROBLEM

Gif courtesy Oakland Museum of California

San Francisco’s west side sits over a 45 square mile water reservoir called the Westside Basin Aquifer. Historically, rainwater seeped through vast areas of sand dunes and collected as naturally filtered fresh water over bedrock hundreds of feet below the surface. As San Francisco has developed over the last hundred years, nearly all of the permeable sand that once fed the aquifer has been paved and built over.

As a result of urban development, impervious surfaces (roads, sidewalks, rooftops) disrupt the hydrological cycle. Water that falls on these surfaces in the city is treated as wastewater in our combined sewer system, overwhelming our treatment centers and disrupting natural infiltration. Each year, San Francisco discharges nearly 2 billion gallons of untreated, combined stormwater and raw sewage into San Francisco Bay and onto Ocean Beach.

A continued failure to be proper stewards of our local hydrological cycle will cause further ecosystem collapse in the the bay delta and maintain high wastewater treatment costs for San Francisco residents.

OUR SOLUTION

In an average winter of rainfall, a 1,200 sq.ft. rooftop (typical for the Sunset District) will collect

16,560
Gallons
of Water

Aquifer recharge through green infrastructure at both residential and commercial scales has the potential to bring the City of San Francisco into better relationship with the ecology and hydrology of our region, reduce costs for the PUC and residents, and build water source resilience.

Why:

  • less strain on our combined sewer system and fewer sewage overflows during storm events

  • rainwater that enters the aquifer can be pumped later as drinking water instead of being mixed with sewage and undergoing a costly treatment process

  • A healthy aquifer underneath San Francisco is a durable alternative source of water for years to come

How:

  • Take the rainwater that falls on our roofs and put it into the ground by installing rainwater catchment and natural infiltration systems

  • Bundle residential properties to at least .5 acres of total roof surface area and disconnect rainwater leaders from the sewer system at scale

  • collaborate with large property owners to secure funding and implement green infrastructure that prioritizes permeable surfaces.

Interested? Contact us about your property

Check your eligibility here

QUALIFYING PROPERTIES MAY BE ELIGIBLE FOR:

  • Substantial private and public subsidies—offsetting up to 90% of total project costs and administrative overhead (up to 100% for qualifying low-income households)

  • NSF Certified roof coating

  • Up to 95% reduction of the stormwater charge on your water bill

  • Native Landscaping

  • System performance monitoring system

  • Grant compliance support

  • Value adds: rainwater tanks, low water irrigation, grey water systems, and more!