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How Does a Septic Tank Work?

Septic Tank Repair   Cleveland TN
Photo By LauriPatterson at istock

Did you know that nearly one in five homes in the United States are not connected to a public sewer? This means that over 20 million homes use septic systems to capture and filter their water waste. These underground tanks are commonly found in rural and remote areas and are also widely used throughout the world. Cleveland, TN is a rural area where septic tanks are common.

Septic tanks are intended to collect sewage and wastewater from households that are not connected to the mains sewer. A septic tank system has a comparatively simple design, but the solid waste needs to be removed regularly. Pumping the septic tank is one of the most important parts of its maintenance and needs to be done correctly and needs to be done often enough to avoid damaging the system and needing a septic tank repair.

If you need a professional septic tank repair service, then there is no better than Metro Plumbing, Heating, and Air. Our septic tank technicians have many years of experience with septic systems and offer many services which include trenchless sewer replacement, septic tank pumping, and septic tank repair and maintenance.

How Does a Septic Tank Work?

A typical septic system consists of a buried septic tank and has a corresponding drainage field, which is connected to the septic tank by pipes. Older septic tanks are made from concrete or fiberglass. More modern septic tanks are made from polyethylene. The tanks are watertight and buried at least five feet from the house, but more generally in the 10- to 25-foot range, with the drainage field located further away still but it depends on the incline of your land.

The septic tanks can vary in size, ranging from a 500-gallon to a 1750-gallon tank. The size of the tank can be larger and depend on the same of your home. All the wastewater that runs out from your home goes through one main drainage pipe into the septic tank. The wastewater will consist of any water and waste from your appliances such as washing machines, and dishwashers, and other fixtures such as your toilet, kitchen sink, bath, and shower.

Septic tanks are used to separate any solids from the wastewater and pretreat the water before final treatment and dispersal in the drainage field.

Modern Septic Tanks

Modern septic tanks usually consist of two chambers. Wastewater flows into the first and gravity causes most of the solid waste to be deposited at the bottom of the chamber. The lighter solid material will float on the surface of the water.

As the chamber fills up the cleaner wastewater will flow into the second chamber through a t-pipe or baffle valve. These prevent sewage from swilling around inside the tank, disturbing the solid waste, while the outlet baffle prevents solid sewage from entering the drainage field. Sloping areas and mountainous regions may require special work to cleanse the drainage field. Gravity will remove any further solid waste not collected in the first chamber. As the second chamber fills up it will flow into the drainage field.

The pipework carrying this wastewater is buried underground deep below and is usually filled by gravel-filled trenches. The pipework is perforated, to allow the wastewater to flow into the soil.


Microbes that live in the soil will break down any remaining solids in the wastewater and kill any bacteria or pathogens that remain to make your home a safe and sanitary place to live.

A poorly maintained septic tank can cause the untreated wastewater to flow back into the house or enter the drain field. If the drain field is swamped with too much water, it can flood, and cause sewage to flow to the surface or create a backup in toilets and sinks. Failure to prevent the buildup of solids in the chambers will result in a septic tank repair from a technician from Metro Plumbing, Heating, and Air.

Aerobic Treatment System

A more modern approach is to have an aerobic treatment system to replace a septic tank. An aerobic treatment system work in a similar manner as a municipal treatment center albeit on a smaller scale.

The wastewater enters a single chamber tank. Where any solid material that settles under gravity or floats on the surface is removed. The wastewater now enters an aerobic treatment unit. This consists of two sections. In the aeration, chamber air is forced into the wastewater to encourage the growth of oxygen-breathing bacteria in the waste.

These bacteria digest most of the remaining solids in the wastewater and so the remaining water is cleaner. The bacteria cannot remove all the waste and any remaining solids are removed by settling as sludge in a settling chamber. This sludge is returned to the aeration chamber because it contains live bacteria that need to be removed from the treated wastewater.

Wastewater Treatments

The treated wastewater is now passed into a chlorinator unit, where any dangerous bacteria is destroyed by adding chlorine to the water. The now treated water is dispersed using a sprinkler system.

As there are solids produced in the treatment they too will need to be removed, the same as for septic tank pumping. The aerobic system will need all the tanks to be emptied of any solid waste. Again, failure to do so will result in you calling the septic tank repair experts from Metro Plumbing, Heating, and Air.

The problem will the aerobic treatment system is that it is expensive to install. If too much or too little wastewater enters the system, then the bacteria may have too little or too much solid waste to digest and the system will not work as efficiently.

Factors That Affect Septic Tank Pumping

Homeowners with septic systems know that they need to have their septic tank occasionally emptied. How often you will need septic tank pumping will depend on several factors.

  • Size of Your Household – this is the most significant factor. The more people that are in your home, the more wastewater will be produced and the greater the amount of solid waste produced. Failure to have your septic tank regularly emptied will increase the chances of your need of a septic tank repair.


  • The more solid waste produced the more frequent you will need pumping.


  • Guest Usage – Again the more guests you have the greater the solid waste produced and the greater the need for pumping. This is important if you regularly rent out rooms in your home or any outhouses for Airbnb and other house rental companies. You do not want to arrange a septic tank repair during a guest visit and ruin your Airbnb rating.


  • Increased Water Usage – The septic tank probably has not been replaced since the day it was installed. A modern home uses more water than in the past. We now have more water appliances in our homes. The more appliances that you have running the greater the amount of work your septic tank will have to do. But using more water-saving devices you will work your septic tankless and so reduce the risk of needing a septic tank repair.


  • The Size of Your Septic Tank – the smaller the tank the faster it will fill up, meaning it will need a septic tank pumping more often. Having a large family or having more water appliances will increase the strain on the tank. You may have had an extension added to your home and the tank may no longer be large enough to cope with the extra demand and you increase the risk of a septic tank repair.


  • The Amount of Rainfall or Snow – more rainfall or snow means that your septic system works harder to deal with all the excess water. This increases the risk of a septic tank repair.


  • Misusing the Septic Tank – by misusing your septic system, you will need to have it pumped more frequently than if you do not. Many people treat their toilets like trash cans. You should only put water, human waste, toilet paper, or some gentle cleaners down your toilet. Wet wipes, Kleenex, and sanitary products cannot break down easily in water and are the cause of many blockages in toilets. Even if they do not block your toilet, they will take longer to break down in the septic tank, causing it to overwork and need a septic tank repair.


  • Pouring Grease and Food Down Your Sink – pouring grease down your sink is a bad idea anyway. The grease and food can stick to the inside of the drainpipes and allow clogs to form, and eventually block your pipes and water will not be able to leave your sink. Allowing the grease and food to enter the septic tank will cause it to overwork and produce more solid waste and the need for more pumping. Do not put food or grease down the sink, dispose of it in the compost bin, or you will need a septic tank repair.


  • Using a Garbage Disposal – Many septic tank pumping companies advise against having a garbage disposal. The garbage disposal usually shreds food into small pieces that should be easily dealt with by the septic tank. However, overuse of the garbage disposal can overwhelm the tank and produce a lot more solid waste requiring more frequent pumping.


  • Using Chemicals to Clean Your Toilet and Sink – You do have to clean your toilet and sink periodically, but we only advise the use of gentle chemicals. Harsh chemicals like drain unblocked liquids do not always remove the blockage. Overuse can cause damage by corroding old pipes and joints. The more chemicals that get into your tank the more they interfere with the balance of bacteria in the tank. As the bacteria digest the solid waste, fewer bacteria will mean a slower rate of breakdown of solids. Do not pour paint, varnish, thinning solvents, or any harsh chemicals down the drain, as these all can lower the amount of bacterial in the tank. The same goes for any unused medicines, these could kill the bacteria too. An overworked system increases the risk of septic tank repair.


  • Wintertime – frozen ground or snow can make it harder to reach the septic tank, making it more difficult to inspect and repair. So can living in a more remote area. During severe weather, it can make it more difficult for your service provider to reach you. It may be advisable to schedule pumping earlier in the year. The harder ground makes it more difficult to have a septic tank repair.


  • How Old Your System Is – the older a septic tank is the harder it must work to deal with the same amount of waste and the more likely you will need a septic tank repair. For any of these reasons, you may need to have your tank pumped more often to avoid damaging your system and needing a septic tank repair.

Things That You Can Do to Help Your Septic Tank

There are a few simple steps you can take so as not to overwhelm your system and need a septic tank repair.

  • Use less harsh chemicals


  • Do not do all your laundry in one day. Too much use of detergents can overwhelm your septic tank.


  • Scape any food from your plates into the compost before you wash them in your dishwasher.


  • Do not pour rubbish down your toilet. So, no cat litter, cigarette ends, or other non-dissolvable materials down the toilet.


  • Inspect your septic tank regularly. If you see a built-up of solid waste schedule a pumping service, or you are going to need a septic tank repair.


  • Following these simple steps will help avoid overwhelming your septic tank and reduce the amount of solid waste produced.

Metro Plumbing, Heating, and Air of Cleveland, TN – Septic Tank Repair Experts

Metro Plumbing has been in business for over 30 years, and we have seen it all, from children’s toys flushed down a toilet to broken down water heaters.

Our great experience and expertise are what sets us apart from the rest. Whatever the job you will receive the highest standards of workmanship and care.

We offer a full septic system maintenance program and will examine all your septic system, the tank, and the drainage field, identifying any problems, and help you decide whether the tank is being pumped often enough.

Whatever your septic tank problem, Metro Plumbing has the proper equipment for the job and the skills to finish it expertly and safely. Give us a call and we will make sure everything stays clean and fresh as the mountain air.

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