Septic tank installation: A step-by-step guide

The installation of your septic tank depends on the type that you have picked. Traditional systems will be discussed here: from the drain, tank to the drain field. Septic systems that use a pump tank, need another tank and a pump to be added. Other systems need to add dirt to form a hill for the drain field. 

A septic tank field has 3 main components:

-The drains bring the sewage in

-The sewage tank

-The drain field. 

Let’s go over each of these and see how they are installed.

1/ The drains that collect and bring the sewage in.

Plumbers add drains to each household sink, shower, and toilet. The water from the toilets is the dirtiest and needs the most processing. These pipes come together and eventually, the dirty water of these are pushed outside the house. Rainwater is generally not added to this mix. The slope of these drains is essential. The water should run fast enough so that the drains get empty. At the same time, the water shouldn’t run too fast as this can leave debris behind. A right mix between air and water assures us that the water takes all the dirt with it. You might need to install a venting system on the standing pipe to get this mix of air and water right.

Using the right diameter for the drain is essential as this makes sure that you don’t have clogs. PVC pipe is simply glued together. Fittings can be used to make this process easier. Make sure that you let the connections dry long enough as the weather affects the drying times (these can be found on the packaging of the glue). It might be needed to drill a hole in the wall to get this pipe from the house to the tank. 

It is possible that this system clogs up. Plumbers have cameras that they can run in these pipes. This makes it easy to inspect and see what is going on. In some instances, a pressure test might be needed to verify that there is a leak.  Clogs are often removed with a water jetter or auger. For a septic tank, an auger might be better as adding a lot of water can disturb the system. These drains are generally made out of PVC or PE. They can last a long time. Just don’t ride over them with a car or other vehicle as this can damage the pipe.

2/ The sewage tank

Image by Aunt_Spray via

The sewage tank is often made out of plastic, fiberglass, or concrete. This is premade in a factory. Some parts might have to be assembled but there is generally not a lot of work that needs to be done to get this finished. The filter in the middle of the tank is often already attached as well. The main challenge is digging out the tank. This is often done with a crane as you need a big hole. Tanks vary in size, depending on the needs of the household, but even the smallest ones need a big hole. 

Before this happens, it might be needed to get a permit. In some instances, you need a study of a geologist that determines the composition of the soil. You have to submit a plan with drawings to the local city council and get them approved. Digging in hard soil can be difficult and other solutions might be used such as a wider tank that is less deep. This also makes sure that the tank is in stable soil. A filled tank can get quite heavy and you want to make sure that it doesn’t sink. This is why some soil is often added after the tank has been installed. 

You have to know how deep the tank has to be. The lid should be above the ground and it has to be possible to install the drainpipe at the right angle. This can require quite some planning but it is important that you get this right. Having to fix this, later on, is annoying and difficult. 

Tanks have to be closed well so that rain or groundwater doesn’t get into them. You might consider adding a sewage tank riser to make it easier to access the tank given that you have to pump it empty every 2-5 years. We have discussed how this can be done HERE.

Before you begin digging, you can outline the location of the hole with flags so that you make sure that you stay within the outlined location. An inspector has to check that your tank is in the right place and you don’t want to move it after installation. Flags make sure that you don’t drift from the intended location. Digging is hard work and it is easy to move a few feet if you don’t pay attention. 

Once the hole has been dug, it is necessary to get the rocks out of the pit. This is often done by hand with a shovel and a bucket. Make sure that the hole is deep enough and that the tank is sitting level when you install it. Compact the earth before you install the tank. You should close the lids of the tank when you install the tank so that dirt doesn’t get in it. Then you can cover the tank with dirt. Pay attention to the two openings and don’t bury these.

3/ The drain field

The drain field spreads out the water that comes out of the tank. This can require more studies to make sure that you have the right soil composition.

A distribution box is used to spread the water that comes out of the sewage tank over the field. This makes sure that it gets distributed properly. Plastic pipes with holes are then used from the distribution box in the field. This field is dug out as well and often filled with gravel but it is possible that big plastic plates are used as well. Depending on the composition of the floor, more advanced systems might be needed. This should have been discussed in the study that has been done. 

You have to take the local rules into account, for example, there are limitations in terms of how close you can get to the property line. 

It is possible to use speed levelers to adjust how much water gets in each drain. Be aware that you can’t use this part of the garden to build things on or to park vehicles. This could damage the pipes. Some plants are also not allowed as the roots can grow in the drains. 

To conclude, installing a septic tank is quite straightforward but needs a lot of planning to get it right. This includes studying the soil, slope of the area and the size of the location. In most instances, you need a permit and the installation gets inspected before it can be used. 

This whole process can seem daunting but it is generally quite easy to install a septic system. For complex systems, it can be a great idea to work with a professional as every part has to be properly connected. If this is not the case, you will have to pump the tank more often. There are a lot of companies that can help you with this. Having to repair a septic system once it has been installed can be quite challenging.