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Wastewater and where you live
Urbanites and suburbanites in the U.S. can rely on most days of the week for their household flushable and sinkable wastes to be treated professionally by their local municipality. Pay a monthly utility bill for the service and that’s that. If, however, you are a citizen of the rural domain, you almost certainly rely on something very much like a septic tank system to remove and safely treat the personal waste you produce while going about (and minding) your daily business(es).
Septic tanks are something that everyone has heard about, but that very few people think carefully about. They are a form of what is called ‘on-site wastewater treatment systems’. This is a polite, technical sounding, process oriented phrase that allows us to mentally sidestep a direct confrontation with the fact that these systems do our dirty work for us. In fact, these systems do our very dirty work for us under- ground all day long so we don’t have to be confronted with the details. . . . Well, that is until they fail, and confrontation can be thrust very unpleasantly upon the owner of the system.
The soil-based septic system
In this post, I want to focus on how sep- tic systems function, rather than how they fail. To put it simply, they function because of soil, our greatest national re- source. And I think that whether you live in the city or the country, this poorly understood microcosm of our American lives provides a fascinating and (dare I say) revelatory insight into the value of soil as an integral component in our global eco-functionality (I may have made this last word up).
Septic systems rely upon the natural physical and biogeochemical processes that occur in soil to absorb and eliminate what might otherwise be health averse environmental pollutants. They are relatively simple, inexpensive, and if properly constructed and maintained, highly effective. This is all largely due to the amazing capacity of soils to assimilate and transform organic matter, nutrients, and pathogenic bacteria. I want to invite you, the reader of this post, to better inform yourself on how the soil performs this silent function for us. I hope when you finish reading, you are able to consider the host of other crucial functions soil performs for us every day without credit or complaint, even as we kick it about and treat it like dirt.
Nuts and Bolts
In a soil-based septic system, household waste water leaves the home through a drainage pipe and enters a tank buried under ground. The tank should detain wastewater long enough to allow the solids to settle to the bottom. Oils and grease float to the top. The liquid fraction of the wastewater is allowed to exit the tank into a drain field. Solids remaining in the tank (sludge) are broken down by micro-organisms more slowly and must be re- moved periodically to maintain septic system functionality.
The drain field is composed of a series of porous pipes leading from the tank to the surrounding subsurface area where the wastewater is allowed to percolate into the soil. The drain field may be a few hundred square feet to an entire acre or more, depend- ing upon the capacity of the soil to treat wastewater and the amount of wastewater to be treated. The soil in the drain field is almost always the soil that was there before the system was in- stalled. Soils are a matrix of irregularly shaped particles arranged in an irregular way so that there is space in between all these particles for air and water. Both air and water occupy and flow through these voids all the time. Plant roots and other living organ- isms, including worms, insects, and microorganisms, also occupy these voids.
In fact, soils contain a host of micro- organisms that begin immediately to work on cleaning your wastewater. There are heterotrophs to break down organic molecules, nitrifiers to convert ammonia to nitrate, denitrifiers to convert nitrate to atmospheric nitrogen (N2 gas), and general predators to consume the E. coli and other pathogens that cause human and animal diseases. After several days’ or weeks’ exposure to the soil, what was once wastewater be- comes environmentally safe water clean enough to percolate into groundwater and/or evaporate from the soil surface to the atmosphere. Viola!
Helping your Septic System Help You
Efficient function of a soil-based septic system requires occasional attention and maintenance. Neglect can lead to some pretty unpleasant outcomes. However, following a few recommended practices helps safeguard your health, your property values, and your neighbors’ opinion of you.
- Do not ask septic systems to handle too much organic matter from oils and greases, or from in-sink garbage disposals.
- Do not flush or sink large amounts of chlorine or other disinfection products. They will sterilize the very micro-organisms you rely on to process wastewater and solids.
- Cleaning products may be disposed of with water in moderation without affecting septic system function.
- Have the system cleaned out (pumped) on a regular schedule as per your installer or local authority’s guidelines.
- There are no recommended ‘wonder’ products that work better to promote the activity of soil microorganisms than the normal stuff you flush.
- Avoid excessive wastewater flows that may overwhelm the system.
- Verify that the systems is not located near a well head to avoid high potential for contamination of your drinking water.
Finally, from the files of the ‘weird and unsupported’, we have to share some of the claims we have heard from septic system owners over the years for things you should flush to make it work better. By the way, none of these ‘nontraditional additives’ do anything to improve your system, and some may hurt it.
- A pound of raw ground meat
- Red wine
- Beer
- Oatmeal
- A packet of yeast
- 1⁄2 a raw chicken (picture that goin’ down the commode)
So next time you walk on some soil, stop and think about all the things it does for us thanklessly. In addition to growing our plants, soil harbors a staggeringly diverse and important ecosystem of macro and microorganisms. It supports and shelters above ground wildlife. It filters water from rain and snow. It mitigates atmospheric carbon dioxide levels. It transforms organic and mineral materials into us- able nutrients and energy. And with- out pay, soil does some of our dirtiest jobs for us every day right in our own back yards.
