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Grey Water

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Installation of Grey Water Systems in Davis

The City passed an ordinance allowing the installation of grey water systems in Davis homes. Grey water is water collected from sinks (excluding the kitchen sink), showers, bathtubs and/or washing machines that can be used for landscape irrigation or toilet flushing. Grey water does not include wastewater from kitchen sinks or dishwashers.

Learn more about this ordinance and California Plumbing Code requirements for grey water system installation.

Permit Requirements for Grey Water Systems

Types of Grey Water Systemsgrey water

  • Laundry to Landscape: the most simple type of grey water system which typically does not require a permit. Grey water is discharged directly from the washing machine through a discharge hose to outdoor landscapes. There are some limitations on laundry to landscape systems including:
    • No spray irrigation
    • No ponding
    • Exterior use only
    • Sub-soil irrigation
  • Branched Drain: connects other grey water sources besides the washing machine. Typically utilizes grey water from showers and/or sinks.
  • Pumped Systems: require a temporary storage tank (less than 24 hours) before the water is pumped to the landscape. If being used for drip irrigation, requires filtration.
  • Dual Drainage Plumbing: typically seen in new construction or major remodels. The grey water drains separately from water

    from the toilet(s) and kitchen sink and enables access to all the household grey water in one pipe.

View the City's Grey Water Systems Presentation for more details and additional system types.