Septic Regulations in Idaho

Over 210,000 Idahoans (36 percent of the state’s population) rely on septic systems to safely dispose of household wastewater. Household wastewater is any water that leaves a home after coming into human contact, for example through cooking, bathing, laundry, or bathroom usage. The role of a septic system is to separate the waste, for example, oils, grease, soap, and solid material, from the water before moving the water to a drain field so that it may safely cycle back into public use through ground water.

Knowing the Local Rules

Septic systems are regulated by the Idaho Department of Environmental Quality. Because not all properties can accommodate septic systems, homeowners in Idaho must first obtain a permit from their local district health department before installing a private onsite waste disposal system. In addition, all properties must first undergo a site inspection before a tank may be installed. Only a licensed installation specialist may install a septic system, and an evaluation of the system is required after installation. If you are considering purchasing property, conducting a site inspection first will assure that you will be able to install a system once you own the home.

Qualified Contractors

The state of Idaho established regulations for licensing of wastewater professionals in 2004. The Board of Drinking and Wastewater Professionals handles certification for professionals on tanks with capacities under 2,500. Most private systems will fall into this category.

Septic Tank Construction

Residents in rural areas who do not have access to public treatment facilities must install a septic system on their property to maintain a healthy water supply. Usually, decentralized systems consist of a 1,000-gallon concrete holding tank and a drain field or leech field. When water leaves the home, it separates within the holding tank. Solids sink to the bottom of the tank, forming the sludge layer, and lighter waste, such as grease or oil, floats to the top, forming the scum layer. The water in the middle is then directed to the drain field or leach field, eventually draining back into the area ground water.

Helpful Contacts

To contact any one the seven local health districts, or to obtain additional information on septic systems in Idaho, please contact:

IDEQ State Office
1410 N. Hilton
Boise, ID 83706
Phone: (208) 373-0502
Fax: (208) 373-0417
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