After attending a graywater workshop in Albuquerque, New Mexico in 2014, Dr. Roslyn Brain McCann, USU Extension Sustainability Specialist, returned to Utah excited to install a residential graywater system in the home she was building in Moab. However, she was soon frustrated by the state’s strict requirements which specified that graywater systems needed to include a holding tank, pump, filters, and engineered plans, which seemed excessive for a simple residential system.

With the help of Jeff Adams, Principal of Terrasophia, LLC, and Orion Rogers, Environmental Health Director of the Southeast Utah Health Department, she began planning for a gravity-fed graywater system in her new home. In 2016, she received the first permit in the state for the installation of a residential graywater system as a pilot program. The goals of the installation were to demonstrate to state authorities that residential graywater systems are an effective approach to reduce the use of culinary water for outdoor irrigation and that graywater is a valuable water resource that may be used safely. If successful, the pilot project would result in a revision to the state’s graywater policy to allow simple, gravity-fed residential systems.

In Utah, graywater is defined as water drained from bathtubs, showers, bathroom wash basins, and laundry washing machines. Simple, gravity-based graywater systems route this water out of the home directly into mulched landscape areas. Systems are sized according to the type and number of fixtures plumbed or the size of the home. Design considerations for these systems include: the size of the discharge area, pipe size and slope, the number of water outlets and mulch shields, and the depth of the gap between the bottom of water outlets and the top of mulch shields. In addition, best management practices for residential graywater systems include prohibition of human contact with graywater, prohibition of ponding, runoff, and/or spraying of graywater, prohibition of contact with the edible portions of plants, and prohibition of biologically or chemically hazardous materials (i.e., bleach) in home fixtures prior to drainage of the water outside the home.

The site context of residential graywater systems must also be considered and include integration of the system with other landscape features and uses, elevations and grading, water sources, and plant water requirements. Differences between the plant water requirements of mature plants and the graywater supply must also be considered, although landscape plant water requirements may be fine tuned to match the graywater budget of the residence.

Dr. Brain’s home gray water system has been a resounding success and is still operating effectively 7 years after installation. As a result of the success of the pilot program, in 2020, the state updated Utah Administrative Code R317-401-1 regulating Graywater Systems to allow Tier 1 and Tier 2 gray water systems. Tier 1 systems are simple, gravity-fed residential systems and Tier 2 systems are anything larger than single or multi-family residential units. The code also requires that graywater installers hold an active Onsite Systems Certification and that an operations and maintenance guide be developed for the graywater system, both for the homeowner and when home ownership changes.

To permit residential graywater systems, local health departments must “opt in” to the new code. Determining whether a local health department has done so is the first step toward facilitating residential graywater systems in local jurisdictions. If a local jurisdiction has not “opted in”, Dr. McCann advises that a signature campaign can be an effective approach in support of the change.

Resources
Gray Water Webinar: https://youtu.be/WEfppCoKbLk
Gray Water Fact Sheet: https://digitalcommons.usu.edu/extension_curall/805/
Relevant Utah Code: https://adminrules.utah.gov/public/rule/R317-401/Current Rules#