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For as long as there’s been indoor plumbing, there’s been a need to dispose of the waste generated in homes and businesses. Septic systems and sewer systems are the two main ways this is done. If you’re wondering how each one works, and the advantages of each relative to the other, Wilson Services has answers.

How They Work

Starting from when you flush your toilet or finish washing your hands, where is the wastewater going? 

In a septic system, it first drains into your septic tank, where solid waste is filtered out by settling and by the inlet and outlet baffle of the tank. The partially treated water that leaves the septic tank is called effluent. The effluent, in turn, makes its way to a drainfield, where it filters through an aggregate layer, then through the soil, to remove bacteria and contaminants before the water returns to the soil and the water table.

In a sewer system, the waste goes to a water treatment plant. There, it undergoes a five-step process. Coagulation and flocculation occur with the addition of positively-charged chemicals to the water, causing small particles to coagulate and form flocculant, larger particles that undergo the next step in the process, a settling called sedimentation. The third step takes the cleaner water at the top of the water supply and passes it through a multi-step filtration process that removes particulate matter, parasites, bacteria, chemicals, and other contaminants. The fourth step, disinfection, kills remaining waterborne pathogens with a chemical like chlorine. The final step returns the treated water to waterways, or even to the municipal water supply.


Neither sewers or septic systems are maintenance-free, and each can develop problems over time. Both, for instance, can be prone to buildups of fats, oils, and solids that restrict flow and can lead to backups and other problems if left unchecked. Both can also develop problems as tree roots, ground shifting, and freezes cause damage to pipes. And flushing things that shouldn’t be flushed or put down drains — including items like “flushable” wipes or kitty litter, household chemicals, drain cleaners, and medications — can lead to problems as well, though they manifest in different ways in septic systems (where the system can be overloaded, or where chemicals can kill off the beneficial bacteria the system relies on) than in sewer systems (where antibiotics, antidepressants, and hormones from birth control show up in municipal water supplies and reservoirs).

Addressing those problems is also a bit different between both types of systems. In a home system, maintenance, repairs, and pumping are the homeowner’s direct responsibility. With a sewer system, everyone who’s hooked up to the system is paying toward its upkeep through property taxes and fees, so the responsibility falls on the municipality.

Benefits and Drawbacks

All things being equal, a septic system is a bit more self-contained, and is off-grid by definition. It also has fewer recurring costs, and if you’re diligent about maintenance and pumping, septic systems are built to last. Sewer systems have their advantages as well, especially insofar as they’re the kind of thing you don’t have to think about unless or until something goes wrong. However, septic has a slight edge here as well; if you have a sewer problem, you may be waiting a bit until the municipality gets around to making repairs. If you have a septic system and you live near Lafayette, Newton, or Byram Township, on the other hand, septic service can be scheduled by calling Wilson Services at 973.383.2112.