Septic System Beginnings
What is a Septic System? This article briefly explores the turn of the century’s early challenges with disease and how proper wastewater disposal came to be. Also, we look at advancements in modern technologies for sewage systems and alternative septic systems.
A modern house is a marvel when you consider all of the things it allows us to not think about. It’s nighttime, and you want to read, and there is a switch, and there is light. You’re thirsty, and there is clean, cold water at the faucet. You are hot or cold, and temperature control is available at the turn of a dial.
You wash dishes and do the laundry and use the toilet, and all of that waste-laden water just… goes away. It wasn’t all that long ago that a great deal of household effort involved water – hauling it for drinking and cooking and cleaning, and getting rid of it when it was dirty with the waste of our everyday lives. In many parts of the world, this daily work still exists.
Systems for transporting water and removing wastewater, particularly human waste, have been around for a long time. They appeared in ancient Greek, Roman, Persian, Indian and Chinese cities out of necessity when many thousands of people lived in close proximity to one another. Surprisingly, the flush toilet has been around for a bit, too.
Thank John Harrington, the godson of Queen Elizabeth I, for inventing it, so that now outhouses and chamber pots are for the most part quaint relics of the past. (Thomas Crapper usually gets the credit here, but he didn’t invent the flush toilet; he was a plumbing magnate who promoted their widespread adoption. As yes, that’s where the euphemism “crap” comes from, at least in North America.) The widespread adoption of the flush toilet had to wait for well-developed water and sewer systems, so for a long time, even stately homes had to rely on “chamber pots” to handle “night soil”, euphemisms that belied our distaste at having to deal with the fact that everybody poops.
A modern home or apartment in the city or suburbs is part of an intricate grid, every dwelling connected to supply lines for electricity, cable TV and internet, natural gas, a water supply, and for the removal of wastewater. Water and sewer systems are much more expensive to install and maintain than the wires and cables that make up the electric, telephone and TV grid, so homes in rural areas mainly rely on private wells as a water supply, and septic systems for wastewater removal.
A septic system is a small wonder of engineering that is born out of an understanding of water flow, hydrology, topography, soil science and microbiology, along with special plumbing components, construction techniques and a host of technological innovations. A functional septic system lets us live our lives rarely thinking about what goes down the many drains in our homes, from the kitchen sink and washing machine to the shower and toilet. When properly designed and installed, it quietly works to remove household liquid waste in a way that is safe for homeowners and safe for the environment.
While appreciating the ingenuity of ancient civilizations and John Harrington for the conveniences we enjoy regarding water and wastewater systems, we should also recognize the work of John Snow, who linked improper wastewater disposal with human disease outbreaks. In the mid-1800’s a cholera outbreak was devastating an area of London. At the time, the manner in which cholera spread from person to person was unknown; professional medical opinion was that it spread through the air.
Snow, pioneering methods in epidemiology, mapped the homes – vast, crowded tenement buildings – of people suffering and dying from cholera, and found they were clustered around a single public water supply, a pump in the neighbourhood square. Snow’s radical solution to the cholera epidemic? He removed the pump handle from the pump! Locals had to travel to neighbouring squares to get their water, and within days the epidemic began to abate and eventually stop. Snow dug deeper and discovered leaking cesspits in the basements of the tenement buildings.
Household chamber pots were emptied in the cesspits; their contents slowly seeping through the ground and contaminating the water supply. Wherever human waste comes into contact with sources of drinking water, disease is certain to follow.
We can consider modern septic systems a legacy of John Snow’s work in linking human health with the sanitary disposal of household wastewater. A well-designed and well-constructed septic system comes at a cost, but there’s perhaps no better cost-benefit outcome than weighing that cost against the convenience and health benefits of efficiently and safely remove waste from the home.
Modern Septic System Installations
A septic system is an “all-natural” way of dealing with household wastewater. Contrast it with industrial wastewater treatment facilities that service cities and towns, treating the sewage of thousands to millions of people, treating millions of gallons of wastewater each day. A home septic system is a simple affair in principle and mimics the process of an industrial facility on a micro scale. But making it work effectively, efficiently and for years of service takes experience and expertise. Think of everything that flows out of the home in water: soap, detergents, dirt, fats, grease, oils, and human waste.
All that wastewater separates into three components – solids, water, and oils, fats & grease. A septic system is designed to separate and treat these three components. The first, separation stage of treatment occurs in the septic tank. The solids settle to the bottom, where microbes get busy breaking down all that organic matter (bits of last night’s spaghetti from washing the dishes, the dirt you washed off your feet after enjoying the day in the garden, and well, yeah, poop). Oils, fats & grease are lighter than water and float on the top, forming a “scum layer.” (It’s like when salad dressing separates into two layers, only much less pleasant.)
This scum is periodically pumped out of the septic tank as a part of routine maintenance. The septic tank is designed so that only the middle, water layer – the effluent – can flow out of the tank. This effluent outflow is directed into the second major component of the septic system, the leaching field. Here, a series of perforated pipes disperse the effluent into a gravel or sand bed, which is buried anywhere from a few inches to a few feet below ground. In some circumstances, the leaching field is constructed above ground and requires pressurized distribution to evenly disperse the effluent. (More on that later, when we look at alternative septic systems.) In the leaching field, the effluent slowly seeps into the ground, where the soil filters suspended solids, dissolved organic material and harmful bacteria and pathogens.
Microorganisms in the soil feast on all of this material in the effluent, breaking down solids and killing bacteria and other pathogens. This is called secondary treatment, and as it continues moving downward through the soil profile, the effluent is gradually purified and reaches the water table. And voila: purified household wastewater rejoins nature’s water cycle.
This illustrates why a good septic system is much more than a septic tank in the ground. The secondary treatment critically relies on carefully controlling what happens between the time the initially treated wastewater (effluent) leaves the septic tank and when it reaches the water table. The soil – and the microbial population within the soil – needs time to purify the water.
Too much water, too quickly, and the soil microbial population’s capacity to remove nutrients and harmful organisms are overwhelmed. A leaching field not sufficiently separated from the water table (the uppermost reach of groundwater), or situated over excessively sandy or porous soil will not provide adequate time or filtering capacity for the soil to do its work properly.
Installing a septic system is not a simple matter of digging up your lawn and dropping a tank and some pipe in the hole. In fact, the entire process is spelled out specifically in BC regulations, which describes everything from obtaining the proper permits, to investigating the soil makeup of the lot where the septic system is going to be installed, to the dimensions of the septic tank and the pipes that will make up the leaching field and the distance of each of these from the lot boundaries, the home, and water supplies.
Septic system placement has to consider the elevation change from the house drain to the septic tank because water does not flow uphill. (But you knew that already.) If the only available site for the site is uphill, then you’ve moved from a simple gravity system to a pump driven system – which is more involved and more costly. The layout of the leaching field is determined by the makeup of the soil.
It goes without saying that if the soil has poor drainage and effluent will leach only very slowly, that’s no good. But the opposite situation is just as problematic – in soil that drains too quickly, the filtering and purifying effect of the soil will be compromised. So, installation requires careful work with heavy equipment, to excavate carefully the placement of the septic tank and the leaching field, not only horizontally in terms of proper distancing from the home, lot boundary, water supply lines and water sources, but also vertically in terms of appropriate elevation changes from the house and vertical spacing of the leaching field from the surface and from the water table.
You will not find septic system installation on a list of common DIY projects. A paint job that looks a little rough, or a newly installed door that squeaks, is one thing; a backed up toilet, and a spongy lawn that smells like a line of Port-a-Potties on the third day of an outdoor music festival, is another thing entirely. Costs for the design and installation of a septic system, or repair of an existing one, are determined by a number of factors: the size of the home or multi-unit rental property, the soil type, the presence of challenging topography such as steep slopes or rocky terrain, or restrictive elements of the site such as bedrock or a high water table.
For a newly installed, conventional gravity-fed system, general costs typically run from $10-12,000 for a 2-bedroom home, up to $18-20,000 for a home of 5 or more bedrooms. Situations that call for pressurized dispersal will increase costs by $5-7,000. More complex systems where high effluent quality must be achieved can be in excess of $30-60,000.
Septic System Installation
Once the system is installed and in use, some testing is required to ensure that it’s functioning properly. Remember, the primary treatment in the septic tank is to remove bulk solids so that the effluent can be suitably purified by leaching through the soil profile. Testing at 3, 6 and 12 months after installation will measure four things: faecal coliform, suspended solids, a measure of microbial activity called biological oxygen demand or BOD, and nitrate, a nutrient that if excessive can have negative consequences on the biodiversity of rivers, streams and lakes. The effluent will be far from squeaky clean of course, but the measures of each of these will have to fall below certain criteria (specified in the BC regulations) to demonstrate that the system is functioning properly.
The pictures, diagrams and videos of septic system construction one finds online makes it all look so easy! Of course, some homes are located on sites that are not amenable to simple, conventional systems, for a variety of reasons. What if your home is located on a beach or lakefront? Or on a steep or rocky slope? Or if you discover that your soil drains poorly, or your soil is sandy and drains too quickly? Or, a small lot might mean that there is simply no room for a leaching field. Fear not; alternative septic designs exist and are quite common.
Alternative Septic Systems
In general, alternative septic systems involve using pumps and electricity, added oxygen, added chemicals, alternative tank designs, imported soil and fill, or a combination of these to increase the efficiency of one or more components that make up a conventional system. It might seem overwhelming to consider what seems to be countless variations and iterations of these alternative septic systems, but just keep in mind that the goal is always to enhance the simple processes of the conventional system; remove solids, encourage the breakdown of suspended and dissolved organic material and nitrates in the primary effluent, and allow the treated effluent to return to the soil and eventually rejoin the water cycle. The major groups of alternative septic system designs involve specially constructed leaching fields, filtration systems, and aeration systems, which we’ll explore briefly here.
Raised bed and septic sand mound systems, while differing slightly, both involve bringing in soil and fill to construct a leaching component where site conditions prevent the installation of a conventional leaching field. For example, sites where the water table is high, or the soil percolates poorly or is too rocky, are all candidates for these alternative septic systems. Think of it as constructing a suitable “site” on top of the actual site. Often bed or mound systems are smaller in size than an equivalent conventional leaching field.
A media filtration system uses, in addition to the primary septic tank, a pump-driven recirculation tank and a filtering compartment filled with sand or other materials to provide additional treatment of the tank effluent before it is released to the leaching field.
Aerobic systems also involve an additional tank to further treat the primary tank effluent. In this case, an aeration device pumps air into the aerobic chamber (that’s the extra tank), providing oxygen to bacteria that will consume and break down organic material and nitrates in the primary effluent. The aerobic chamber doesn’t completely eliminate the need for a leaching field, but the size of the field can be significantly reduced.
Of course, anything that eliminates the amount of wastewater going into the septic system can have a significant impact on its effectiveness. Lo-flow showerheads and faucet aerators can reduce the amount of water going down the drain in the first place, as can the newer low-flow toilets that use much less water per flush than older toilets. To really reduce demands on a septic system, a composting toilet eliminates toilet waste from the septic tank entirely and also eliminates one of the greatest demands on household water use.
Importing soil and fill, adding extra tanks, the need for electric power and other add-ons found with alternative systems does increase installation costs, but the good news is that available technology, along with careful design, planning and installation, means that almost any site can be outfitted with an effective septic system. And then, when we wash the dishes or take a shower or use the toilet, it will all just… go away.