Decentralized Water Policy Council

now called:

California Onsite Water Association (COWA)

2014 – Present

In 2014, the OAEC WATER Institute, together with Sierra Watershed Progressive,  representatives from regulatory agencies, and other stakeholders, launched a policy initiative designed to localize California’s waters – The Decentralized Water Policy Council.  The Council brought together allies working to increase water efficiency and reuse in commercial and residential settings throughout California.  In 2017, the DWPC transitioned to the California Onsite Water Association (COWA).

COWA supports a collaboration of multiple stake-holder water activists, engineers, regulators and practitioners committed to removing barriers to reusing and conserving water onsite in all our land use activities.  This coalition convenes the annual Localizing California Waters Conference and creates effective integrated water management strategies through decentralized water projects and working committees that accomplish policy goals.

Legalizing and removing barriers to protect water is one of OAEC’s strategies for change.

Localizing California Water

COWA Working Areas:

  • Blackwater (including Composting Toilets)
  • Greywater
  • Rain and Stormwater
  • Ground and Surface water

Currently COWA’s over-arching goals are:

  • Streamline and modernize regulatory standards for onsite water technologies
  • Advance legislation and policy that embraces localized water as part of a comprehensive, sustainable management
  • Increase public awareness and information encouraging localized water solutions
  • Promote best management practices for system installations, operations, and maintenance

Roofwater Harvesting in California

Water, Energy and Climate – Why water reuse matters

decentralized waterWater reuse is at the core of Conservation Hydrology.

Nearly twenty percent of California’s electricity and more than thirty percent of non-power plant natural gas is used for water-related purposes: for collection, production, transport, treatment and delivery of water to end users, during the consumption and use of water, and for collection, treatment, and disposal of wastewater [1].  Thus keeping and reusing water in place rather than transporting it long distances conserves both water and energy. This connection between water and energy is referred to as the water-energy nexus.

Updating federal, state, regional and municipal policies to adopt modern onsite water reuse technologies has the potential to save up to 14 million-acre feet per year – that’s equal to 35% of current annual water use in California, and the equivalent of the water used by all of California’s cities in a year. This reduction in demand for new water would also dramatically reduce the amount of energy used and thus significantly reduce the GHGs emitted by California’s water-energy nexus [2].

[1] Francis Spivy-Weber, Vice-Chair, State Water Resources Control Board
[2] Drought-Stricken California Could Save Up to 14 Million Acre-Feet of Water; Enough to Supply All the State’s Cities Annually, Issue Brief June 2014, NRDC and Pacific Institute

Founding members by stakeholder group

Steering Committee

CA decentralized water council


Decentralized Water Policy Council



Greywater-ready buildings – model ordinance

This document provides model ordinance language for municipalities to adopt “greywater – ready” building mandates for new construction and is a great resource for forward-thinking architects, plumbers and contractors wishing to integrate simple provisions for greywater into their new building projects.

It details how drainage piping can be plumbed to make it easy, at any future point in time, to install a diverter valve and direct greywater to the garden.  Problems arise, for example, if a second story bathroom does not have separate greywater drain piping coming down the wall to where it can be easily diverted, either low in the wall ( if there is a slab) or in the crawlspace – it can be exorbitantly expensive and disruptive to try to alter drainage piping in the ceiling under a bathroom at a later date. It is equally difficult to access greywater from a groundfloor bathroom if there is a slab and provision has not been made to route the greywater pipes to a point where they can be diverted.  Indeed, planning is best done in advance!

Download free PDF>

WATER Institute

WATER logo picture

The Occidental Arts & Ecology Center WATER Institute develops innovative science-based solutions for communities and the environment to address the legacy of hydrologically destructive land-use practices and policies on California’s watersheds, and the urgent need to address the impacts of climate change on the water cycle.


WATER Institute