Graywater Systems - Defining Terms, Advantages, and Utah Regulations

Oct 16, 2026

Uploaded by jay

Graywater Systems explains what graywater and clearwater are, contrasts graywater with blackwater, and outlines how graywater can be harvested for irrigation. It describes natural treatment benefits in soil, potential impacts on water demand and costs, and the role of plants and microorganisms in filtering contaminants. The document also reviews Utah’s regulatory framework, including Tier 1 and Tier 2 system types, and lists typical components needed to design, install, and maintain systems.

LanguageEnglish

CategoryHealthcare

FormatPDF

Pages4

Reading Time10 min

AccessFree to download

Defining Terms: Graywater, Blackwater, and Clearwater

Why Use Graywater and Clearwater for Irrigation

Advantages of Graywater

Graywater in Utah

Tier 1 (Residential Only)

Tier 2 (Multi-Family and Commercial)

Graywater System Components

Graywater Sources

Collection and Distribution Plumbing

Receiving Landscape

People and Professional Requirements

Graywater Systems Roslynn Brain, Jeremy Lynch & Kelly Kopp (Departments of Environment & Society, and Plants, Soils & Climate: Utah State University) Updated with revised rule in 2020 by Roslynn Brain McCann, Jeffrey Adams (TerraSophia LLC) & Orion Rogers (Southeast Utah Health Department) Defining Terms: Graywater, Blackwater and Clearwater Why irrigate only with treated drinking water when you can supplement your irrigation needs through an effective graywater system? The Utah Office of Administrative Rules defines graywater (accepted spelling also includes greywater and gray water) as “wastewater from bathtubs, showers, bathroom washbasins, clothes washing machines, or laundry tubs. Graywater does not include wastewater from toilets, kitchen sinks, photo lab sinks, dishwashers, water softeners, garage floor drains, or other sources that pose a public health hazard”(2020, R317-401-2). In Utah, toilet, kitchen sink and dishwasher water are categorized as “blackwater”. Graywater is an abundant resource in both residential and commercial buildings. According to Brad Lancaster of Rainwater Harvesting for Drylands and Beyond,“graywater harvesting is the practice of directing graywater to the primary root zone (top 2 feet or 0.6m of the soil) of perennial plants to help grow beautiful and productive landscapes while achieving wastewater treatment without using energy or chemicals. Plants and microorganisms in the soil consume and filter the organic nutrients and bacteria found in graywater, treating it naturally and returning clean water to the water cycle”(2010, p.294) . Though not suitable as drinking water, graywater can be used for irrigation, even for growing fruit on trees and shrubs with woody stems that serve as additional filters for any contaminants that may be present. Installing earthworks for a gravity-fed graywater system in Moab, UT (pipe outlet into green mulch shield). Credit-Roslynn Brain McCann Clearwater is solid-free wastewater which includes water produced while waiting for hot water from the faucet to heat up, refrigerator compressor drip, swamp cooler and air conditioning ‘sweat,’ and more. Clearwater, like graywater, is an underutilized landscape irrigation resource ripe for harvest in most commercial buildings and homes. Why take the time to establish a system for graywater and clearwater use? A primary answer is: resource abundance in light of anticipated hotter, drier weather in the Southwest (Brain, Adams, & Lynch, 2017). The arid West has some of the highest per capita residential water use due to landscape irrigation (EPA, 2018) . For example, irrigation accounts for around 72% of Utah’s and 82% of Idaho’s water use (Milligan, 2018) . The Pie Chart on the next page shows that 50-60% of average residential indoor water use could become potential graywater sources. The secondary use of at-home graywater and clearwater resources can help offset high rates of water consumption and associated municipal water costs. 1 Version: May 2020 sustainability/2020/01pr Advantages of Graywater Graywater use results in: • Effective water treatment (graywater is treated in the upper, most biologically active region of the soil); • Reduced use of ground and surface water resources for landscape irrigation; • Reduced use of energy and chemicals for water and wastewater treatment; • Improved plant growth; • Reclamation of nutrients (also, wastewater disposal in rivers/oceans is a significant form of pollution); • Increased awareness of natural cycles and personal water usage; and • Landscape irrigation source in preparation for potential future drought irrigation restrictions. Graywater in Utah In 2004, the Utah Water Quality Board adopted a rule (R317) allowing the use of graywater from baths, showers, bathroom sinks and washing machines for residential drip irrigation systems. Walt Baker, past director of the Utah Division of Water Quality, said the graywater legislation was “

FAQs

What is graywater according to Utah’s administrative rules?

Graywater is wastewater from bathtubs, showers, bathroom washbasins, clothes washing machines, or laundry tubs, and it excludes sources that pose a public health hazard such as toilets, kitchen sinks, and dishwashers. In Utah, toilet, kitchen sink, and dishwasher water is categorized as blackwater.

How is graywater naturally treated and why is it useful for irrigation?

Graywater is treated in the upper, biologically active soil where plants and microorganisms consume and filter organic nutrients and bacteria. Although not suitable for drinking, it can support irrigation, including fruit trees and shrubs with woody stems that act as additional filters.

What are the differences between Tier 1 and Tier 2 graywater systems in Utah?

Tier 1 is intended for residential use and is a gravity-fed system without surge tanks, pretreatment, or pressurized components, making it simple to operate. Tier 2 applies to multi-family and commercial settings and may include a surge tank, pretreatment, drip line irrigation, or pressurized components.

Oct 16, 2026

Uploaded by jay