How often are septic tanks emptied, and where do the contents go?
A septic pump truck cleans the scum, sludge, and effluent from a septic tank. In modern homes, drains have a way of remaining innocuous. Unless the toilet is overflowing or the bath spigot is filling the tub with blood, plumbers and exorcists aren’t usually on our minds! Thanks to the simple push of a lever, the waste remains out of sight and out of mind. About one-third of Americans have a septic system treating the waste in their homes. By design, these systems are fairly simple. All drains in the home converge to a single pipe that leads to the septic tank buried outside.
When the wastewater from your toilet, shower, sinks, and washing machine leave your house, it’s combined. When it hits the septic tank, however, it begins to separate.
The heaviest particulate matter in the waste, called sludge, sinks to the bottom. At the top of the tank, fats, oils and proteins form the floating scum layer. In the middle is the comparatively clear liquid layer called effluent or gray water. Combined, these components are called septage.
Septic systems are designed so that only the effluent is discharged from the tank into the drain field (also called the leach field). This is simply a set of pipes with holes drilled into them that release the effluent below ground (but above the water table).
The effluent is degraded enough to be well-filtered by good soil. There’s plenty of organic material left in the effluent, though, which acts as a fertilizer. This is why the drain field usually boasts the healthiest segment of the yard above it.
Simple as their design may be, septic systems require the homeowner to monitor them before problems arise. Usually, once a problem becomes obvious, it’s too late for any simple solution.
Fixing big septic problems often requires thousands of dollars worth of parts and labor. Fortunately, a little maintenance can go a long way in avoiding problems. Read the next page to find out how often a septic tank should be pumped out.
To help prevent clogging and build-up, some companies produce toilet paper that dissolves in water. It’s helpful, but you should still have your tank inspected and pumped regularly. Even with a healthy microbial ecosystem breaking down the septage, a well-functioning septic system and good drain field, the sludge and scum layers in your tank will build up over time.
The sludge and scum should be pumped out periodically — generally when the bottom of the floating scum layer is within 6 inches (15.2 centimeters) of the outlet pipe or the top of the sunken sludge layer is within 12 inches (30.4 centimeters) of it. Without a well-developed power of extrasensory perception, it’s impossible to tell when your waste has reached these levels!
This is why it’s recommended that people with a septic tank have their system checked every year. Having your system inspected includes getting your sludge and scum levels measured, checking the system’s pipes and mechanisms and inspecting the drain field to make sure it’s percolating the effluent properly. The average septic tank system usually requires pumping every one to three years.
Without regular pumping of the septic tank, the system can overflow. Sometimes overflow can lead back to the house, where toilets and drains belch forth what’s supposed to be in the septic tank.
Overflow can also lead to a sudden deluge of unprocessed waste flooding the drain field. When this happens, water can seep above ground, which leads to a flooded yard and run-off into nearby water bodies like creeks and rivers.