How often to pump residential septic tank - Ask Extension
How often should a residential septic tank be pumped. I've had mine pumped once in the last 30 years, about 15 years ago. My in-laws lived in the sa...
Knowledgebase
How often to pump residential septic tank #728978
Asked October 05, 2020, 9:32 PM EDT
How often should a residential septic tank be pumped. I've had mine pumped once in the last 30 years, about 15 years ago. My in-laws lived in the same house for 60 years and never had it pumped. But, I've been told they should be pumped every 3-5 years or it could ruin the drain field. I'm not sure what size tank I have. The house was built in the early 1980's. I'm guessing 1500 gallons? We don't put oils or egg shells or other non-septic items/substances into the septic. But, there's probably some that gets through anyway. Any advice would be appreciated. Thanks in advance, Jay.
Marion County Oregon
Expert Response
Greetings,
Thank you for reaching out to Extension. The following was taken from this publication: Septic Tank Maintenance (OSU Extension Service). I highly recommend that you review that whole article as well as review the additional resources on our Well Water and Septic Resource page http://wellwater.oregonstate.edu/septic-systems-0. There are additional management considerations that you should be addressing in addition to pumping.
The frequency of pumping depends on several factors: • Capacity of septic tank • Flow of wastewater • Volume of solids in wastewater (more solids if garbage disposal is used) Table 1 (see in the first publication I linked to above) gives the estimated pumping frequencies according to septic tank capacity and household size. The frequencies were calculated to provide a minimum of 24 hours of wastewater retention assuming 50 percent digestion of the retained solids.
In Oregon, a 1,000-gallon septic tank is used for a home with three bedrooms. If six people reside in a three-bedroom house, the tank should be pumped every 1.5 years. If the same system serves a family of two, the tank would be ready for pumping every 5.9 years. Systems installed before the current rules and regulations may have smaller septic tanks.
As shown in Table 1 (see publication), some tanks may need to be pumped more often than once a year. It’s important to note that the soil absorption field will not fail immediately when a full tank is not pumped. However, the septic tank is no longer protecting the soil absorption field from solids. Continued neglect will result in Table 1 (see publication link above to view table).—Estimated septic tank pumping frequencies in years (for year-round residence).
More frequent pumping is needed if garbage disposal is used. James A. Moore, Extension agricultural engineer, Oregon State University. Archival copy. For current version, see: https://catalog.extension.oregonstate.edu/ec1343 failure of the soil absorption field, and it may need to be replaced. In some cases, replacement of the absorption area may not be possible due to site limitations.
Thank you for reaching out to Extension. The following was taken from this publication: Septic Tank Maintenance (OSU Extension Service). I highly recommend that you review that whole article as well as review the additional resources on our Well Water and Septic Resource page http://wellwater.oregonstate.edu/septic-systems-0. There are additional management considerations that you should be addressing in addition to pumping.
The frequency of pumping depends on several factors: • Capacity of septic tank • Flow of wastewater • Volume of solids in wastewater (more solids if garbage disposal is used) Table 1 (see in the first publication I linked to above) gives the estimated pumping frequencies according to septic tank capacity and household size. The frequencies were calculated to provide a minimum of 24 hours of wastewater retention assuming 50 percent digestion of the retained solids.
In Oregon, a 1,000-gallon septic tank is used for a home with three bedrooms. If six people reside in a three-bedroom house, the tank should be pumped every 1.5 years. If the same system serves a family of two, the tank would be ready for pumping every 5.9 years. Systems installed before the current rules and regulations may have smaller septic tanks.
As shown in Table 1 (see publication), some tanks may need to be pumped more often than once a year. It’s important to note that the soil absorption field will not fail immediately when a full tank is not pumped. However, the septic tank is no longer protecting the soil absorption field from solids. Continued neglect will result in Table 1 (see publication link above to view table).—Estimated septic tank pumping frequencies in years (for year-round residence).
More frequent pumping is needed if garbage disposal is used. James A. Moore, Extension agricultural engineer, Oregon State University. Archival copy. For current version, see: https://catalog.extension.oregonstate.edu/ec1343 failure of the soil absorption field, and it may need to be replaced. In some cases, replacement of the absorption area may not be possible due to site limitations.
