Virtually all farms use a septic system or similar onsite wastewater treatment system. While these systems are generally economical and safe, household wastewater can contain contaminants that degrade water quality for such uses as drinking, stock watering, food preparation and cleaning.
Potential contaminants in household wastewater include disease-causing bacteria, infectious viruses, household chemicals, and excess nutrients, such as nitrate. Viruses can infect the liver, causing hepatitis. They can also infect the lining of the intestine, causing gastroenteritis (vomiting and diarrhea). If coliform organisms (a group of indicator bacteria) are found in your well water, they show that the water is potentially dangerous for drinking and food preparation. Your septic system is one potential source, along with livestock yards and others.
The quantity of wastewater can also present an environmental concern. Too much water entering the home treatment system reduces the efficiency of the system and can shorten its life.
Your drinking water is least likely to be contaminated if you follow appropriate management procedures or dispose of wastewater in any location that is off the farm site. However, proper offsite disposal practices are essential to avoid risking contamination that could affect the water supplies and health of others.
The goal of Farm*A*Syst is to help you protect the groundwater that supplies your drinking water.
How will this worksheet help me protect my drinking water?
- It will take you step by step through your household wastewater treatment practices.
- It will rank your activities according to how they might affect the groundwater that provides your drinking water supplies.
- It will provide you with easy-to-understand rankings that will help you analyze the risk level of your household wastewater treatment practices.
- It will help you determine which of your practices are reasonably safe and effective, and which practices might require modification to better protect your drinking water.
These terms may help you make more accurate assessments when completing Worksheet #6. They may also help clarify some of the terms used in Fact Sheet #6.
Approved disposal site: A site for land application of wastewater or tank pumpage that meets state standards and is approved by the New Mexico Environment Department.
Cesspool: Covered excavation in the ground that receives sewage directly from a building's sanitary drainage system. It is designed to retain the organic matter and solids and permit liquid to seep into soil cavities. Cesspools are prohibited in New Mexico.
Clear water infiltration: Entry of water into a system that does not need treatment, such as rainfall or tile drainage, through unsealed joints, access ports and cracks.
Design capacity: Maximum volume of liquid that can be treated in a particular wastewater treatment system. For systems that include subsurface wastewater disposal and distribution, capacity is also based on the soils ability to accept and treat sewage effluent. In filling out the worksheet, if you don't know the design capacity of your system, use 150 gallons per bedroom per day as an estimate.
Effluent: Liquid discharged from a septic tank or other treatment tank.
Holding tank: An approved watertight receptacle for the collection and holding of sewage.
Hydraulic loading rate: The volume of waste discharged per unit area per unit time.
Off-site disposal: Disposal of wastewater or sludge off the farm, as at a municipal treatment plant or approved disposal site.
Scum: Floatable solids, such as grease and fat.
Seepage pit (dry well): Underground receptacle constructed to permit disposal of septic tank effluent, treated wastes or clear wastes by soil absorption through its bottom and walls.
Sludge: Settleable, partially decomposed solids resulting from biological, chemical or physical wastewater treatment.
Risk Contamination from Household Wastewater Treatment
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The Farm*A*Syst Program is a cooperative program funded nationally by: USDA Cooperative State Research Education Service (CSREES), USDA Natural Resources Conservation Service (NRCS), and the US Environmental Protection Agency. This worksheet has been produced by the National Farm*A*Syst Office located at B142 Steenbock Library, 550 Babcock Drive, Madison, WI 53706-1293, Phone: (608) 262-0024. This worksheet is based on the original Wisconsin Farmstead Assessment Program. The principal author for this worksheet was Susan Jones, US EPA Region V, Water Division, and University of Wisconsin-Extension, Cooperative Extension. |
July 24, 1998
Dennis Hoffman, Project Leader
Steve Dagitz, Webmaster