Your Point of Source Waste Water Treatment (POSWWT) plant is one of the most efficient and environmentally friendly means of treating raw sewage. Yes, your septic system can reduce the introduction of toxins and excess nutrients into our soil, ground water, and aquifer.1 According to the Florida Department of Health, Bureau of Environmental Health, when a septic tank is working properly, it naturally removes most of the pollutants that can make you sick.” If your drainfield rests on Florida sand- even just a few feet deep- you have an even more efficient system.2
Key reasons why your POSWWT system is efficient.
1. Point of source systems handle much lower volumes of waste water than a centralized system. This means that even if there were a break in pipes or a highly unusual cracked or ruptured septic tank3, the amount of raw sewage leaking into the surrounding soil is a matter of a few hundred gallons instead of thousands or millions in a centralized system handling waste water from thousands of homes. Repairs can also be made quickly and economically.
2. Home owners have the ability to manage what goes into the system that could reduce efficiency. Municipalities have no control and no testing requirements to determine levels of poisons, pharmaceuticals, petroleum distillates, or pesticides that may have been dumped into their system.
3. Low cost and low energy consumption. The typical system requires no electricity at all, works by gravity and requires no pumping, valves or meters. Some systems in low lying areas may be designed with two holding tanks one equipped with a sump pump to lift effluent into a higher tank for dispersal in a raised drain field. Some newer systems may have agitation and aeration to introduce oxygen in the system. However, as we will see, if you are on sand that sandy drainfield can become your oxygen source.
4. Most interesting is the fact that sand is the absolute best medium for reducing toxins and nutrient overload. Not sand by itself, but sand with its ample oxygen and the resulting active biology that is the real work horse in sewage treatment.2
So, taking these points into consideration lets evaluate what you can do to maintain and prolong the life of your septic tank and drainfield.
Maintenance is a key to reducing expensive repairs with everything in your home. Fortunately your septic system was discovered to be an efficient system for waste control thousands of years ago. The biology that makes this true has not changed but the components have improved and require less physical labor to maintain.
This brochure from the Florida Department of Health, http://www.floridahealth.gov/environmental-health/onsite-sewage/_documents/septictanksystemsbrochure.pdf, offers many helpful suggestions so there is no need to repeat them here.
However one of the most important things you can do is to protect the trillions of living organisms in your septic tank and drainfield that will consume and digest the toxins, nutrients and other pollutants that are part of waste water. In fact, with proper care, your on-site system can do this more efficiently than a municipal system because you have more control over it.
The place to start is to not dump anything down the drain or into the toilet that will kill living bacteria. A well-functioning system with an active bacterial population can handle, consume, and digest even toxic chemicals. Property owners can increase the efficiency and widen the list of toxins eliminated by adding commercially available strains of bacteria. Municipal WWT plants can and should do the same thing. To ensure the healthiest system eliminate things like excessive chlorine bleach, phosphate soaps, and all drain cleaners. Chlorine bleach in moderate amounts isn’t as bad for a septic system as you may have heard. But even a little drain cleaner may be terrible. One study found that it took nearly two gallons of liquid bleach but only about a teaspoon of chemical drain cleaner to kill the beneficial bacteria in a septic tank.4 There are safe and effective bacterial drain cleaners that will break down fats, oils, grease, starches, proteins and other substrates that clog pipes and drains.
Also solids that don’t belong in your toilet can clog the system and back up waste. Never flush or dump fats, oils, coffee grounds, cat litter, diapers or feminine hygiene products. Any fabric or item that expands in water should not enter your system.
While newer septic systems may include aeration to introduce oxygen they may not be necessary if you are adding good bacteria strains to your system and sand with a moderate to high percolation rate is under your drainfield.
The bacteria that begin the process of consumption and digestion of solids and water soluble toxins and pollutants are the anaerobic bacteria that are naturally present in your septic tank. If the tank is not filled with items that will clog the exit port there is no other maintenance required other than pumping the tank every 3-5 years to remove excess sludge.
However, if the property owner introduces additional strains of naturally occurring bacteria the consumption of sludge can be greatly increased to the point no pumping is required. A good septic pumping company will tell you when they are wasting your money. Ours told us there was no need to pump the last time they were here. We have a large family with many daily flushes and sink drains.
Here is where our Florida sand proves to be a real benefit to proper effluent impurity reduction. Sand filters are now used to clean raw water from ponds and lakes to 99% pure drinking water. This is an excellent science adapted for poor countries around the world.
Fortunately, we don’t need to drink raw ground water but there is every indication that sandy drain fields in Florida have the perfect combination of microbes, food supply (effluent), oxygen supply, residence time, and moisture. We know this because research around the world has determined what the ideal levels of each of these factors are.
Recently our company, Organic by Design, LLC, tested the soil in 8 different drain fields near lateral discharge pipes and 1’-2’ below the lateral. All samples were taken in Ormond by the Sea, Florida from just west of the Atlantic Ocean to just east of the Halifax River which is an important estuary for Florida’s east coast. We wanted to test the sand that was near the point of discharge to see what nutrients could be found. We did not test for toxins or other pollutants but the same biology has proven to destroy and consume those as well.
Nitrogen pollution is a major concern for Florida’s water bodies. In agriculture the required amount of nitrogen to grow an excellent crop of corn is about 200 lbs. per acre. Most soil samples taken in Central Florida show a natural level of about 80 lbs. per acre. So recommendations for growing grass, trees, shrubs, and crops always call for the addition of more nitrogen. The results from an independent lab in MO found a range of 32, 28, 16, 16, 16, 12, 4 and 4 lbs. per acre in the soil samples we took from Ormond by the Sea. This is not enough Nitrogen to grow a weak dog fennel.
Control tests in the same area outside of the drain fields showed levels of nitrogen at 88 and 80 lbs. N per acre. So the question is where did all this Nitrogen go? Is it just running rapidly through our sandy soils and into the ground water? The answer is no. It would not show up at 80 lbs. per acre in the top 6” of soil and be a fraction of that 4 feet deep with the nitrogen that is assumed to be added by the drain field effluent. They both show levels at one point of time. If it was leaching so rapidly in the lower sand it would also be leaching even more rapidly from the top soil because of rain and irrigation and be captured by soil samples in the lower levels. The test show no such movement.
The Report on the status of sewage disposal and collection in Volusia County, Florida – 2013 estimates the ground water level to be from 22” to 72”. There was no water observed in these tests to a depth of 60”. Personal observation from landscape planting in the area and discussions with septic tank installers report no water found at depths from 72” to 96” during the wet summer months.
There is an even more important detail most speculative reports addressing septic systems leave out. That is the active biology that accumulates in a sand filter with a good food source. Here is what good research from around the world has taught us.5 Within 48 hours of a sand filter (our drain fields) being used there is a biofilm layer of living microbes consisting mostly of bacteria but also fungi, protozoa, rotifers, and other tiny aquatic insect larvae. This hypogeal layer also contains decomposing organic matter, iron, manganese, and silica all acting as a fine filter and slowing down the rate of percolation. Studies prove there is no rapid leaching once this layer is formed.
There are requirements to produce and maintain this sticky layer of your living filter. 5 The first is the sand itself. Without sand the other requirements could not be met. This slime is actually a chemical compound secreted by the bacteria to anchor themselves to the bottom and sidewalls of the drainage piping, the aggregate in the absorption bed, the soil interface, and to each other to prevent being washed away by the water flow through the septic system. The bacteria serve a vital purpose in a septic system by absorbing the organic waste, removing pathogens, and breaking it down into soluble byproducts. Without these beneficial bacteria, the septic system would not work.
The bacteria actually grows in two layers. 5 On top is the aerobic bacteria, they require oxygen to grow and are the most efficient in breaking down pollutants and nutrients. However, there will be an anaerobic layer growing underneath and surrounded by aerobic layers that protect it from oxygen. This anaerobic bacteria is important because it is what consumes iron to form the sticky layer that slows down the rate of percolation in the sand. It also uses sulfur from the raw waste material for its energy. So one bacteria gives the sand a fine filtration ability similar to a net so the aerobic bacteria have time to consume whatever is slowed down as it travels with the water column. Where there is a good food source there are always predators. It is the same in all of nature, a constant food source draws a predator population.
This is where our sand and subtropical environment come in to make our septic systems the perfect waste treatment plants. In order for the hypogeal layer to form and thrive it must have both the anaerobic layer to give the holding (slowing down the rate of percolation) capacity and aerobic forms of bacteria to provide the most efficient consumption. These layers will be found in the pipes and laterals of the entire system. There must be balance so the laterals are not clogged and the population of digesting consuming bacteria can grab the food supply.
The bacterial layer must have a good source of oxygen for the aerobic bacteria and other soil microbes important in establishing the hypogeal layer. 5 Our sand is porous enough to contain a great deal of oxygen to support this bacteria while keeping the anaerobic in check, literally underneath the aerobic. So a porous sand is beneficial and provides the oxygen requirement necessary to form this layer. High percolation rates are only detrimental if you purposely leave out the science of biology that is teaming in our soils. In reality, porous sand is the oxygen delivery system and quite beneficial.
The system must also not be flooded and our deep sands prevent that. Constant flooding would fill all the pore spaces pushing out available oxygen. But research also shows the hypogeal layer is in the 12”-15” of sand just below the drainfield laterals. Bacterial activity below that depth is very small. The foxes stay where the rabbits are, trap them, and feast. The drain fields we tested from near the ocean to right on the river had laterals so far above any ground water it could not be found. In reality, we only need a foot of sand under the laterals to do the job.
The next requirement for a productive hypogeal layer is temperature. The temperature range for these beneficial bacteria is 39 F to 122 F with 39-77 F being optimal. Our soil averages 75 F three feet below the surface. Perfect once again.
Moisture is also required to maintain the bacterial layer. Since the food source is arriving in a relatively steady flow at low volume the result is life sustaining moisture but no flooding- the optimum environment.
The last requirement is a steady food source which is what the septic system is designed to provide. So keep it flowing, unobstructed and don’t introduce harsh drain cleaners to kill out your crop of beneficial soil microbes. If you own a septic system you’re a farmer growing a crop of happy bacteria and soil microbes created to eliminate toxins and excess nutrients naturally in our soil. This is an environmentalists dream come true.
Septic systems have the food source but we can take one more step to keep them running problem free providing the best results for our families and environment. As part of their regular maintenance homeowners would be wise to add a six strain Bacillus bacteria blend to their systems on a monthly basis. This would ensure optimum levels of bacteria and would augment the bacteria naturally found in a septic tank. A good blend would have strains that reduce or eliminate biosolids, poisons, chemicals, and nutrients. They would also serve to keep the perfect balance in the pipes and laterals between anaerobic and aerobic bacteria.
The low rates of nutrients found in our soil samples indicates the expected hypogeal layer has formed and is working. This layer would be the most likely reason the load just under the drain field laterals is a fraction of the normal N content in our controls. It is common to read predictions of high levels of nutrient saturation by those who assume septic systems are great polluters. There was no saturation layer found in any of our soil samples, quite the opposite. These results are enough to encourage the State of Florida and Volusia County to have their own testing done by an independent testing source.
Given the problematic rates of nutrient build up in our waterways one of the best solutions could be properly installed and functioning septic tanks. Once the biology is understood it is likely we will find other sources of nutrient and toxin saturation like agricultural runoff, spreading of biosolids, leaking and malfunctioning municipal systems, and the practice of EPA approved municipal dumping of raw sewage and partially treated effluent into our waterways by millions of gallons a day to be the most likely source of excess nutrients. Municipal dumping and spreading of highly toxic biosolids may currently be legal but we may find it is the real culprit overloading the system as can be seen in any area water body. So let’s do more testing and find out.
It seems homeowners on septic systems are the easy targets for expensive and unnecessary change in the name of environmental responsibility. Maybe legislators just don’t know the truth. Let’s do more testing and change that. Homeowners are no competition for the effective lobby found in all layers of government by the development industry. Right now it is possible the money to be made by local governments in municipal utilities is the real driver. It is also notable to consider the fact that the presence of a sewage treatment plants tend to give rise to very high density development. Who is the driver there? Let’s protect our water supply and search for the truth. That will need to be driven by the people in every community who truly care about being good stewards of our environment.
2International Journal of Current Microbiology and Applied Sciences ISSN: 2319-7706 Volume 7 Number 07 (2018) https://pdfs.semanticscholar.org/d208/d9a24828656eec3f393bcad525717b6ad5b2.pdf?fbclid=IwAR0TXbxdw78YN0wHFv6Qyxk6SkoeRqQNcOjzRjvgq5K_JsoEiyPZVf0gWHc
3A concrete septic tank can last 40 years to nearly indefinitely, though poor quality concrete or acidic ground water may result in deteriorated baffles or tank components. https://inspectapedia.com/septic/Septic_System_Life.php, https://buildingadvisor.com/how-long-can-septic-system-last/
5Prem Ranjan and Manjeet Prem. 2018. Schmutzdecke- A Filtration Layer of Slow Sand Filter. Int.J.Curr.Microbiol.App.Sci. 7(07): 637-645. doi: https://doi.org/10.20546/ijcmas.2018.707.077
For more information contact: Jeff Brower, Organic by Design, LLC
DeLeon Springs, FL