Safe disposal of human waste is a concern of any town or city. Wastewater can contain dangerous pathogens like bacteria and viruses (such as hepatitis, salmonella, E. coli, and cholera), and elements like nitrogen and phosphates which can harm wildlife and local water quality.
Municipal sewer systems and water treatment facilities have a number of ways to counteract these dangers, but what about houses that are off the sewage grid? In the Greater Victoria area, houses without sewer service typically have a septic tank system on their property — which the homeowners are responsible for.
In this post I'll be going over the general workings of a septic tank system, and what you as a homeowner might need to know to keep your tank safe and maintained.
How Does A Septic Tank Work?
Septic tank systems usually have three main components: an inlet pipe, the septic tank itself, and a drain field.
The inlet pipe carries black water (wastewater directly from the toilet) and grey water (wastewater from other sources such as showers and dishwashers) from your home to the septic tank.
The septic tank is an underground watertight container often made of concrete, fiberglass, or polyethylene. As wastewater enters the tank, a community of anaerobic bacteria (bacteria that can survive without oxygen) breaks the waste down into liquid, a sludge that sinks to the bottom, and a fatty scum that floats to the top. After two days, new wastewater is broken down by about 40%, by which time the bacteria has eaten most of the dangerous pathogens.
The liquid portion of the waste then flows through an outlet pipe to an underground drain field (also known as a leach field), which is often a series of perforated pipes in gravel troughs that allow the liquid to slowly drain into the soil. In the drain field, bacteria continues to clean the wastewater and the soil filters it further, preventing harmful organic material from reaching groundwater supplies. Depending on your property, your system might also have a reserve drain field, meant as a backup in case your main drain field fails.
Finally, some properties don't have soil suitable for filtering septic waste, or are too close to other septic systems to have a standard drain field. In these cases an alternative septic system may be in place that uses sand, peat, plastic, aerators, nearby wetlands, or other methods of removing toxins. These systems might have mechanical components like float switches and pumps, and may need special maintenance.
How To Maintain A Septic System
Keeping a septic system in good repair is always a good investment. Poorly maintained systems often fail, and septic tanks and drain fields are expensive to repair or replace. And if you want to sell your home, your septic system will need to be in proper working order.
In addition to financial concerns, a poorly-maintained septic system can present a serious health risk. Tanks and drain fields can be overloaded and cause untreated sewage to seep up through your lawn, back up through your plumbing, or spill pollutants into local water supplies, which you can wind up legally liable for.
When you acquire a home with a septic system, the septic tank and drain field (and reserve drain field, if it exists) should be clearly marked on the “as-built” drawing of the property. If you've misplaced the drawing, a copy may be filed in your local land records. If your septic tank is part of a newer system, you may be able to locate it simply by spotting risers or manhole covers in your yard. If your tank is part of an older system and has no risers, a septic inspector or pumper should be able to help you locate it.
Pump Out Your Septic Tank On A Schedule
Over time, sludge and scum will build up in your septic tank and require removal. This is done through regular pumping of your tank.
How often your septic system will need to be pumped will depend on the size of your household, the size of your septic system, your volume of water usage, and the amount of solids in your wastewater. Most standard systems require pumping every 3 to 5 years.
Your septic pumper should provide you with a service report listing any repairs that were done, as well as the final condition of your tank.
Some septic tank additives are available that claim to break down sludge, removing the need to have your tank pumped, but their effectiveness is questionable. General professional opinion is that regular pumping is the best way to keep a septic system working properly.
Have Your System Inspected Regularly
Typical septic systems should be inspected every 3 years, and alternative systems (especially those with mechanical parts) once a year. A professional inspector will check for leaks, measure the scum and sludge layers in your tank, and inform you of how often it needs to be pumped. They should also inspect the performance of your drain field, if possible, and make sure it hasn't built up any major blockages.
Spread Out Your Water Use
The anaerobic bacteria in septic tanks take time to do their job. Tanks are designed to always contain a little bit of wastewater so that the bacteria don't die, and to maximize the amount of time (known as “holding time”) that it takes for wastewater to travel from the inlet pipe to the drainage field.
An increase in water usage in your home also increases the amount of flow through your septic tank, which in turn decreases the holding time and the amount of time the bacteria spends processing your waste. This heightens the risk of pathogens passing unfiltered through the system, and the risk of flooding in your drain field.
As a result, short periods of high water usage (like doing all the household laundry in one day) can be harmful to your septic system, leaving it without time to recover. It's better to spread water usage throughout the week as evenly as possible, keeping in mind the capacity of your septic tank and drain field.
Upgrading water-using appliances and ensuring you have well-maintained plumbing can also lighten the load on your septic system. Water purifiers and softeners often pump extra water into your tank. A leaky toilet reservoir can add up to 760 litres to your system a day, and leaky faucets aren't much better. Repair them and prevent that extra water from entering your septic system. Look for Energy Star-rated washing machines and dishwashers; they use less water as well as less energy than older models. And finally, high-efficiency toilets can decrease your water usage by 15% or more.
Don't Pour Toxic Things Down The Drain (Or The Toilet)
Non-dissolvable items and household chemicals can be some of the biggest risks to a septic system. Paper towels, baby wipes, cat litter, coffee grounds, dental floss, and other items can become trapped and clog various parts of the system. Liquids like paint, bleach, antifreeze, and gasoline can weaken or destroy the bacteria treating the wastewater in your tank and drain field. Fats, oils, and grease can cause your tank's scum layer to grow quickly and overload the system, or at least require more frequent pumping.
Here's a list of common substances that should not enter your septic system:
Toxic cleaners (especially ones labelled “Danger” or “Poison”)
- Drain cleaners (use boiling water plus baking soda and vinegar instead)
- Deodorizing chemicals
- Petroleum products
- Any non-waste solids that aren't toilet paper
Latex paints aren't as harmful as oil-based paints, but they should also be reduced. Squeeze and wipe as much paint as possible from brushes and rollers before rinsing them in the sink. Dispose of any unused paint at a local hazardous waste centre.
Other substances that can clog your drain field over time include laundry lint, mineral soil, bone and eggshell fragments, and fats dispersed in detergents. You can minimize their harm by limiting their introduction to your septic system, and giving the bacteria in your tank plenty of time to digest them.
Be Careful With Your Yard
Septic tanks and drain fields are often found in backyards, but it's important to know exactly where they are in order to prevent accidental damage. You don't want to drive or park on any part of your septic system, as it can compact the drainage soil and damage pipes or other components. Plants and trees should be grown away from the system so that their roots don't disrupt it; only grass should grow over and around your tank and drain field. And non-septic drains and drainage systems should be kept away from the drain field in order to minimize the chance of flooding.
Keep An Eye Out
Most septic system failures are easy to spot. Pooling water or muddy soil around your system or basement, sinks backing up when you do laundry, and oddly-coloured grass above your drain field are all good indicators that something is wrong.
But if you keep up with proper care and regular maintenance, you can help prevent problems before they start, and enjoy the benefits of your own mini waste treatment facility.