Conserving Our Water Resources is Important
Our ground water and surface water supplies are at risk of overuse in many areas. The demand can be greater than the amount supplied by rain and snowmelt. Water conservation, wastewater recycling, and reuse is becoming more important due to increases in:
- Demand on potable water resources.
- Cost of treating wastewater.
- Regulations requiring greater flows for streams and rivers, which reduces irrigation sources.
- Demand for sustainable building options.
Keep in mind that it is often cheaper, easier, and safer to use less water in the first place than to recycle or reuse wastewater. However, there are many ways for homeowners and water system managers to conserve water.
To learn more about water conservation see Water Use Efficiency and EPA's Water Sense.
Water Recycling is Important
By design, on-site sewage systems, also known as septic systems, naturally recycle wastewater by recharging ground water with appropriately treated effluent. To ensure on-site sewage systems are treating waste effectively and not polluting the ground water, building and home owners must make sure their systems are working properly.
Learn how septic systems work and how to maintain them.
Options for Conserving Water and Recycling Wastewater
On-site sewage systems (OSS)
Options for on-site sewage systems with design flow of less than 3,500 gallons per day (individual homes and small buildings).
OSS Using Subsurface (Underground) Drip Irrigation
Description: A type of on-site sewage system designed to treat residential-strength wastewater so that the treated wastewater (effluent) can be used for subsurface irrigation of plants. A subsurface drip system is an efficient pressurized wastewater distribution system that can deliver small, precise doses of effluent to shallow subsurface dispersal fields.
Benefits:
- Uses all the wastewater from a building.
- Produces healthy, fast-growing plants.
- Gives you the ability to put water exactly where it's needed and keep paths and areas between plants dry. This reduces both waste and weeding.
- The amount of wastewater used during irrigation can be controlled precisely so that nearly all of it remains in the root zone where the plant can use it the most.
- Delivers equal amounts of water to plants over a wide area.
Notes: These types of systems are designed to treat residential strength wastewater so that it can be safely used for subsurface irrigation. All wastewater from the system is recycled.
To learn more, see Recommended Standards and Guidance for Subsurface Drip Systems (PDF).
Rules: Chapter 246-272A WAC
Permits: Issued by the local health jurisdiction
Greywater OSS
Description: An on-site sewage system used in a building equipped with waterless toilets. This system must be designed as an approved on-site sewage system under Chapter 246-272A WAC. Under these rules, the system may be designed and used as a subsurface irrigation system.
Benefits: Water conservation is realized by two processes:
- The total volume of water used is reduced (human wastes are not transported through piping).
- All wastewater is used for subsurface irrigation of plants, shrubs, trees, and turf.
To learn more, see Recommended Standards and Guidance for Water Conserving On-site Wastewater Treatment Systems (PDF).
Notes: Because a greywater on-site sewage system is a permanent wastewater system, it must be designed to handle normal variations of wastewater strength year-round and have a surge capacity to handle a variety of water use scenarios. To ensure public health and environmental protection, this system must be designed and maintained using the on-site sewage system rules.
Counties have until July 2014 to implement the greywater reuse rule. Before considering greywater irrigation, contact your local health jurisdiction to make sure you are not violating local regulations.
Rules: Chapter 246-272A WAC
Permits: Issued by the local health jurisdiction
Greywater Reuse for Subsurface Irrigation
Description: Greywater is used only for subsurface irrigation applied at a rate to meet the water needs of the plants during the growing season. "Greywater" means domestic type flows from bathtubs, showers, bathroom sinks, washing machines, dishwashers, and kitchen or utility sinks. Greywater does not include flow from a toilet or urinal.
The building must be served by an approved wastewater system to use these rules.
Benefits: The rule, Chapter 246-274 WAC, provides building owners with simple, cost-effective options for reusing greywater for subsurface irrigation. It is intended to encourage water conservation while protecting public health and water quality.
Notes: The state rule became effective July 31, 2011. Local health jurisdictions (LHJ) need to write local codes to allow this use. Check with your LHJ to find out if it is allowed where you live.
These systems are for seasonal use only, when plants are growing and need to be watered. The amount of water allowed is limited to what can be used by the plants, taking in account evaporation loss. They are designed differently than on-site sewage systems. The permanent wastewater system must be designed to handle normal variations of wastewater strength year-round and have a surge capacity to handle a variety of water use scenarios.
Counties have until July 2014 to implement the greywater reuse rule. Before considering greywater irrigation, contact your local health jurisdiction to make sure you are not violating local regulations.
To learn more about Greywater reuse visit Department of Health's Greywater Reuse webpage.
Rules: Chapter 246-274 WAC
Permits: Issued by the local health jurisdiction
Greywater Recycling Inside of Buildings and Rainwater Collection
Description: Recycling of any water, including greywater, inside of a building and using it for flushing toilets and other nonpotable water uses is covered under the Washington State Plumbing Code.
Benefits: When you think about it, flushing toilets with drinking water doesn't make sense. We spend a lot of money collecting and treating water so that it is drinkable and then we use it to flush the toilet? In some locations you may be allowed to have your home plumbed so that you can recycle wastewater from your washing machine, sinks, tub, and shower to flush your toilet.
Notes: Check with the local building department to determine what is allowed. If you live in King County, read Doing Our Business (PDF) and RainWise to learn more.
Rules: Chapter 51-56-1600 WAC
Permits: Issued by the local building or plumbing department.
Large On-Site Sewage Systems
On-site sewage systems with design flow of 3,500 to 100,000 gallons per day (large on-site sewage systems).
Description: A LOSS is designed to convey, store, treat, and provide subsurface soil treatment and disposal of domestic sewage for a design flow of 3,500 to 100,000 gallons per day.
Benefits: LOSS offer an alternative to centralized municipal sewage treatment plants and can serve from 10 to about 370 individual residences, or equivalent flows from schools and churches, campgrounds and recreation vehicle parks, resorts or state park sites, or smaller cities or towns. All on-site sewage systems (including LOSS) potentially provide groundwater recharge. When the loading rate is greater than the needs of the plants and evaporation, ground water recharge is possible. The primary legal reuse application for LOSS is subsurface landscape irrigation. All other beneficial uses require a reclaimed water permit. The safest and most effective way to irrigate landscape plants with LOSS effluent is by using subsurface drip tubing for distribution.
Notes: A LOSS that utilizes a properly designed subsurface drip system is a good option for recycling wastewater. To maximize irrigation efficiency the system designer must consider environmental conditions including soil characteristics, plant types, and local weather conditions.
Rules: Chapter 246-272B WAC
Permits: Issued by WA State Department of Health Large On-site Sewage Systems (LOSS) Program
Reclaimed Water
Description: Reclaimed water is a water supply produced by treatment of municipal or domestic wastewater. It's an important component of good water management. Domestic wastewater and small amounts of industrial process water or storm water can be sources of reclaimed water.
Benefits: Reclaimed water has a wide variety of beneficial uses such as surface irrigation, industrial process and cooling water, toilet flushing, dust control, construction activities, and many other uses of non-potable water supplies. It is also used as a resource to create, restore, and enhance wetlands, recharge our groundwater supplies, and increase the flows in our rivers and streams.
Notes: Reclaimed water is a hybrid program with elements from numerous federal and state regulations. These include water resource management, water supplies, urban and watershed planning, wastewater management, wetlands, groundwater and surface water protection, and public health and safety. It is important to realize that these requirements are established for different purposes.
Rules: Chapter 90.46 RCW
Permits: Issued by WA State Department of Ecology Reclaimed Water Program
Contact Information
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Contact the regulatory authority identified with each option for more detailed information.
- For general questions about water conservation contact wastewatermgmt@doh.wa.gov.