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What is a Septic Tank?

Brendan McGuigan
Brendan McGuigan

A septic tank is a large tank meant to store sewage waste while it settles. The tank design is used by nearly a fourth of the population in the United States, and is also widely used throughout the world.

The septic tank is one part of a standard rural septic system, the other part being the leach field. Sewage enters the tank from the house where it is left to separate. Heavy solids settle to the bottom, while the relatively clear water rises to the top where it is allowed to leach off into the earth. Once in the leach field, any remaining solids are taken care of, and the water rejoins the greater water table.

Rural homes often have septic tanks instead of city sewer systems.
Rural homes often have septic tanks instead of city sewer systems.

Solids left in a septic tank mostly break down through the digestion of anaerobic processes. Not all the solids will work their way out, however, and occasionally a tank must be drained before it reaches capacity. The speed at which this filling occurs depends on the size of the tank, the amount of waste being pumped into it, the temperature the tank is kept at, and whether a large amount of non-biodegradable solids have been added to the tank.

The truck that comes to remove solid waste from a septic tank is commonly referred to as a honey truck or honey wagon. Most rural areas have only one septic truck working their region, as the rate of removal tends to be fairly low. In some high-density areas, a number of septic companies may be needed, but it tends to be the case that as populations grow to levels where multiple trucks would be required, environmental factors force the transition to a centralized waste treatment system anyway.

A typical septic tank is constructed of either some sort of metal treated against corrosion or, more commonly, a sturdy plastic. Some may be fitted with an additional heating apparatus as well, to aid in the anaerobic breakdown of solid waste and lessen the frequency with which the tank needs to be drained. An average-sized septic tank has a capacity of anywhere from 1,000 to 1,500 gallons (3,785 to 5,678 liters), though for high-impact areas large tanks with 5,000 to 10,000 gallon (18,927 to 37,854 liters) capacities exist. It requires a considerable amount of work to install a tank, with a percolation test required to locate an ideal place for a leach field, and heavy machinery required to dig a sufficient pit in which to place it.

Discussion Comments


A good rule of thumb when caring for a septic tank is to make sure that you shouldn't flush or use a lot of harsh chemicals around your home. If you are constantly putting something like bleach and heavy duty cleaner down the drain, it can actually kill off the good bacteria working to breakdown your waste.

Having your good bacteria die off is a huge problem, as your septic tank will no longer work as well as it should and waste will accumulate faster requiring more maintenance.

Also, don't ever dump grease down your drains. This is a known cause of clogging your septic tank and causing nasty backups.


My grandmother had a septic tank at her home, so I recall being curious about what it was and how it worked. There is actually quite a bit of maintenance involved in one if you go by the book and care for it properly.

You should make sure that the area around the septic drainfield is kept free of excess water, by making sure no sprinklers, or roof gutters empty into that area. There should be no trees around either, as their roots can damage the tank.

Also, septic tanks are touchy, so never flush anything except toilet paper and regular waste or you'll get a clog very quickly.

For the most part, you should have it drained every 3 to 5 years if you have a 1000-gallon tank and a family of four.


@indemnifyme- You're preaching to the choir my friend! I purchased the septic tank coverage on my homeowners policy when I bought my house. I'm glad I did.

A few of my neighbors have had problems with their septic tank systems. The ones who had their septic tanks covered under their insurance simply paid their deductible and then the rest was covered under their insurance. However I'm pretty sure my other neighbor who didn't purchase the coverage is still paying off the repairs that were done on his septic tank!


If you have a septic tank you should definitely have septic tank coverage somewhere on your homeowners insurance. It varies by state but on many policies septic tank or sewer backup coverage is an additional coverage.

This means when you are purchasing your homeowners policy the insurance agent will probably ask you if you want septic tank coverage. You should say yes! It does cost extra but it is very worthwhile.

Septic tank problems can be very costly especially if the septic tank backs up. If something like this happens and you said no to the septic tank coverage just to be frugal you will probably regret it!


@Kat919 - Septic tank maintenance is nothing to be afraid of! As far as house shopping, you shouldn't be able to see where the tank is by looking at the yard. Once you have a contract and you're in the "due diligence" phase, make sure to have the tank pumped and inspected. Most septic tanks will run for a long, long time with almost no maintenance, but if there's a problem, it can be expensive, so you definitely want to know what you're getting into.

Another thing to be aware of is to make sure the tank is really big enough for the house. A friend of mine bought a house with an unfinished "bonus room." When she applied for a permit to have the room finished, she was denied--her septic tank wasn't big enough, legally, for a four-bedroom house. That will vary from place to place, so check it out locally.

Really, you'll probably never know the difference between having sewer and having septic, unless you're in the habit of washing eight loads of laundry all in one day. (Hint: don't do that on a septic tank! Space out laundry and dishwasher loads, especially if your house is filled to capacity.)


I'm looking to buy a house and a lot of the ones in the area I'm interested in have septic systems. Should I run from those? I lived in a house growing up that was on the city sewer, and since then I've always lived in apartments. Is it a lot of trouble to have a septic tank? What should I be aware of?

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    • Rural homes often have septic tanks instead of city sewer systems.
      By: Vitaly Krivosheev
      Rural homes often have septic tanks instead of city sewer systems.