Frequently Asked Questions About Septic Systems

A septic system is a mini wastewater treatment plant. Wastewater flows from your house into the septic tank. There, heavy solids sink to the bottom (sludge) and lighter grease and oils float to the top (scum). The liquid effluent in the middle flows out to a drainfield, where it's slowly released into the soil, which acts as a natural filter to remove harmful bacteria before the water returns to the groundwater system.

The drainfield (also called leach field or absorption field) is a network of perforated pipes buried in gravel-filled trenches. After wastewater is partially treated in your septic tank, the liquid effluent flows into the drainfield, where it slowly soaks into the soil. The soil acts as a natural filter, removing harmful bacteria, viruses, and nutrients before the water reaches the groundwater.

If the drainfield gets overloaded by too much water or escaping solids, the soil can clog, causing soggy areas in your yard, unpleasant smells, or even sewage backups. Protect your drainfield by:

• Not parking or driving on it
• Diverting roof/gutter runoff away from the area
• Having your tank pumped regularly so solids never reach the field
• Avoiding excessive water use and never flushing anything except waste and toilet paper

The vast majority of conventional septic systems are anaerobic, meaning they use bacteria that do not require oxygen to break down waste. This process is slow and only partially effective. Aerobic systems use an aerator to pump oxygen into the tank, which supports much more efficient oxygen-loving bacteria. These aerobic bacteria can break down waste up to 30 times faster and more completely, resulting in cleaner effluent leaving the tank and less strain on your drainfield.

A biomat is a slimy layer of bacteria and organic matter that forms in the soil of your drainfield where the effluent enters. A thin, healthy biomat is actually beneficial, as it helps filter out pathogens. However, when too many solids escape the septic tank, the biomat grows too thick, clogging the soil pores and preventing water from being absorbed. This is the primary cause of drainfield failure.

Start by locating where the main sewer pipe exits your house in the basement or crawlspace. The septic tank is usually located 10-20 feet directly out from that point. You can use a thin metal probe to gently poke the ground in that area until you hit the hard, flat surface of the tank lid. If your system has risers, you may see one or two green plastic lids flush with the ground. If all else fails, your local health department may have an "as-built" diagram of your property showing the location.

With proper maintenance, a septic tank itself can last for 40 years or more. The drainfield, however, is the component most prone to failure. A well-maintained drainfield can last 20-30 years, but one that is overloaded with solids or water can fail in less than half that time.

According to the EPA, most households should have their septic tank pumped every **3 to 5 years**. The exact frequency depends on your tank size, household size, and water usage. Pumping annually is rarely necessary and can be a waste of money. The goal is to pump the tank before the sludge layer gets so high that solids can escape into the drainfield.

The cost varies by location and tank size, but you can generally expect to pay between $300 and $600 for a routine pumping. Emergency pump-outs, especially on nights or weekends, can cost significantly more, sometimes upwards of $800.

A professional will locate and open your septic tank lid. They will measure the sludge and scum layers to determine if pumping is needed. They will also check the tank's baffles for damage, look for signs of leaks or cracks in the tank, and assess the overall health of the drainfield area for any signs of failure.

A properly installed and used septic system should not freeze. The continuous flow of warm water from the house and the heat generated by bacterial activity keep the tank warm. A healthy layer of grass or snow over the drainfield provides excellent insulation. Avoid clearing snow off the drainfield, and fix any leaky faucets that could cause a slow, constant trickle of cold water, which is more likely to freeze in the pipes.

You should have your system professionally inspected every 1-3 years. This inspection checks the sludge and scum levels, ensures the tank's baffles are intact, and looks for early signs of drainfield issues. It's also crucial to maintain your drainfield by never parking on it and diverting rainwater away from it.

Common signs include: foul odors around the tank or drainfield, slow-draining sinks and toilets, gurgling sounds in the plumbing, water backing up into the house, and unusually green or spongy grass over the drainfield.

A septic alarm indicates a high water level in your pump tank, which means effluent is not being pumped to the drainfield correctly. This could be due to a pump failure, a clogged filter, or a power outage. You should immediately reduce your water usage to a bare minimum and call a septic professional for service. Do not ignore the alarm, as it is warning you of an imminent backup.

That rotten-egg smell is typically hydrogen sulfide gas, a byproduct of the anaerobic bacteria in your tank. Odors usually mean the system is overloaded, the tank needs pumping, or a vent pipe is blocked. A healthy, balanced system should not produce noticeable odors in your yard.

If a drainfield is completely clogged with solids, replacement is often the only option. However, if the clogging is in its early stages, some remedial actions can help. Reducing water usage, having the tank pumped immediately, and introducing an aeration system to break down the biomat can, in some cases, help restore function to a marginally clogged drainfield—but this is not guaranteed. If the field is severely clogged or has failed, replacement is typically required. Prevention is always the best and cheapest strategy.

Unfortunately, a fully failed drainfield (one that is completely clogged with solids) usually needs to be replaced, which is a major excavation project costing anywhere from $5,000 to $20,000 or more. This is why preventing drainfield failure is the most important and cost-effective strategy for any septic owner.

The only things that should ever be flushed are human waste and toilet paper. Never flush items like "flushable" wipes, paper towels, feminine hygiene products, dental floss, cotton swabs, cat litter, coffee grounds, or cigarette butts. These items do not break down and will rapidly fill your tank and clog your system.

Yes, they can be. A garbage disposal can increase the amount of solid waste entering your tank by up to 50%. This means you will need to pump your tank much more frequently. If you use a garbage disposal, it's even more critical to have a proper maintenance schedule.

Similar to bleach, normal use of antibacterial hand soaps is unlikely to harm your septic system. The large volume of water in the tank dilutes them to a level where they don't significantly impact the bacteria population. The bigger concern is overuse of harsh disinfectants or pouring them down the drain in large amounts.

Normal, moderate use of household cleaners, including bleach, is generally fine and will not permanently harm the bacteria in your septic tank. The large volume of water in the tank dilutes the chemicals. However, you should avoid pouring large quantities of harsh chemicals, solvents, or paint down the drain at one time, as this can disrupt the system's biological balance.

According to the EPA and numerous university studies, a healthy septic system does NOT need routine additives. Your system gets all the bacteria it needs from the waste that is flushed into it. Most common store-bought additives are unnecessary at best and can be harmful at worst by disrupting the natural settling process in the tank.

This is a common myth. While these items do contain bacteria or yeast, they are not necessary and provide no real benefit. Your septic tank already has billions of bacteria perfectly adapted to that environment from the waste that enters it. Adding these items is simply adding more organic solids that the system has to process, which is counterproductive.

Most traditional septic additives are not recommended by experts, as a healthy system naturally maintains its own bacterial balance. However, some newer products, such as oxygen-releasing tablets like Septifix, are designed to create a more oxygen-rich (aerobic) environment in the tank. This may help support aerobic bacteria, which can break down waste more efficiently than anaerobic bacteria.

It’s important to note that these tablets are not the same as installing a mechanical aerator, and there is limited independent scientific research confirming their long-term effectiveness. While some users report benefits such as odor reduction, results can vary, and these products are not guaranteed to fix serious septic issues or replace regular maintenance and pumping. For persistent problems or failed systems, professional evaluation is always recommended.

Traditional chemical and biological additives will not fix a failing system and can make it worse. They cannot make a clogged drainfield unclog itself. The only proven approach for remediation is converting the tank to a fully aerobic environment using a powered aerator, which may help break down the biomat in some cases. While products like oxygen-releasing tablets may be able to help, severely failed systems still require professional evaluation and likely replacement.