Graywater is water that is collected from bathroom and laundry sinks, bathtubs, showers, and laundry machines and put to a second use (e.g., subsurface irrigation or toilet/urinal flushing). Graywater does not include water from toilets, urinals, kitchen sinks, dishwashers, or non-laundry utility sinks. While currently to allow graywater use in Colorado local jurisdictions must adopt a graywater control program that meets all requirements outlined in Regulation 86, starting in January 1, 2026 graywater can be installed in all new construction unless a local government has adopted an ordinance prohibiting the installation of graywater and provides notice to the Colorado Department of Public Health and Environment per HB24-1362.

Currently, there are two kinds of graywater systems allowed in Colorado:

1. Subsurface irrigation: Sub-surface irrigation systems take water from graywater sources, move the graywater through a coarse filter, and then pump the water into underground irrigation systems to protect users’ health and safety. A common application of a subsurface irrigation system is a laundry to landscape system. Due to the underground piping, retrofitting can be expensive, and they are most common in a new development setting. This may change with technology advancements and future adjustments to the Regulation 86 requirements.
2. Toilet and urinal flushing: Toilet and urinal flushing systems take water from graywater sources, moves the graywater through a coarse filter and disinfection process, and then replumbs the water to a toilet or urinal. Due to the graywater system equipment cost and size it is usually not cost effective to retrofit homes or facilities with graywater systems, and therefore their application currently makes the most sense in new developments. This may change with technology advancements and future adjustments to the Regulation 86 requirements.

Despite being permitted since June 2015, there has not been a lot of uptake in graywater systems. Table 16 summarizes some of the Colorado communities who have adopted a graywater control program. 

Table 16. Communities in Colorado that have adopted graywater regulations

It is assumed that the lack of uptake is partially due to cost and low return on investment. As part of their adoption, the City of Fort Collins estimated graywater costs, water savings and return on investment for a toilet and urinal flushing system.

Table 17. Toilet flushing graywater system impact

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