Septic Tank Sizes

Mukulika Mukherjee May 13, 2019
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A septic tank is essential for hygienic disposal of household sewage. If you are planning to build a house, then read on to know about the available standard septic tank sizes...
A septic system is a small system designed to treat sewage and waste water that drains into it. Before you install a septic system in your house, you need permissions from the local body. After that, you need to find a suitable location for the installation of the septic system and also find out what size of septic tank would be suitable for you.
For determining the location, a process termed as the percolation test is carried out. This test takes into consideration the amount of time taken for water to get absorbed into the lower layers of the soil. There are basically two components of a septic system: the septic lines and the septic tank.
A septic tank is called so because of the anaerobic bacteria that grows in it. This bacteria is responsible for the decomposition of the waste in the sewage water. A septic tank consists of three parts: a tank, an inlet pipe for the waste water to flow in, and a septic drain. Modern septic tanks have two chambers.
When sewage flows into the first chamber, the solid waste dissolves in it, settles down and is decomposed by the anaerobic bacteria present inside the tank. The remaining sewage passes to the second chamber where the degradation of smaller solid particles takes place.
The liquid sewage is then let out into the drain field, which is also referred to as the seepage field. It is essential to clean the tank at regular intervals to prevent solid non-degradable wastes from accumulating in the tank.

Standard Sizes of Septic Tanks

Generally, a septic tank is chosen on the basis of the quantity of water used. However, another way to determine how large a septic tank you may require is on the basis of the number of rooms you have. It all depends on the regulations and criteria of the region where you live.
The septic tank cost varies with the design of the septic tank. Here we'll have a look at the range of septic tank sizes, based on both the criteria discussed before.

Standard Sizes as per Water Usage

First let's see which are the available sizes of septic tanks if you wish to get one as per the usage of water in your house. Depending on the volume of waste sewage water generated per day, the standard sizes of septic tanks are as given ahead.

900 gallons

If the volume of waste water generated per day is up to 500 gallons, then it is recommended that you use a septic tank of 900 gallons.

1200 gallons

If the waste water volume per day is anything between 600 and 700 gallons, the ideal size of the septic tank is 1200 gallons.

1500 gallons

A septic tank of 1500 gallons is ideal for 800 to 900 gallons of waste water generated per day.

1900 gallons

If volume of sewage generated per day is around 1000 gallons, then you should choose a 1900 gallon septic tank.

3200 gallons

A septic tank of 3200 gallons is meant for a per day sewage water generation of around 2000 gallons.

Standard Sizes as per House Size

When the required septic tank size is determined based on the size of the house, it is done on the basis of number of bedrooms in the house and it is assumed that all the rooms would be in use.
The information given ahead will give you an idea of the standard size of septic tanks required for houses with certain number of bedrooms. Needless to say, the more the number of bedrooms in a house, the larger would be the size of the septic tank needed.

750 gallons

If you have a house with one or two bedrooms, then you should opt for a septic tank of 750 gallons.

1000 gallons

A septic tank of 1000 gallons is ideal for a house with three bedrooms.

1200 gallons

For a four-bedroom house, the ideal size of the septic tank is 1200 gallons.

1500 gallons

If you are planning for a septic tank for a house with either five or six bedrooms, then you need a septic tank of 1500 gallons.
This was about the different septic tank sizes. To prevent the flow of non-degradable solids into the tank, you can attach a filter at the inlet of the tank. This will facilitate smooth functioning of your septic tank. You can have septic tanks made of plastic or concrete, depending on your requirements.
If all you need is a small tank, then you can opt for one made of plastic. However, concrete is preferred for larger tanks for the simple reason that it is strong and durable. A well-maintained septic tank can last for years together.