01 JAN

Septic tank installation

Written by Drain Ratz Plumbing , Posted in Sewage Treatment Solutions

How to install a septic tank: 

A septic tank should always be connected to french drain unless of course you are installing a digestor. There is a difference in the installation process.This easy DIY installation guide is only for the septic tank installation. There are also 2 types of pipelines to consider and this installation only covers a septic tank on a single pipe line.How to install a french drain is more complicated and will soon follow on the next seriess of articles for Dummies.

Easy DIY Installation. Get ready to go all in and get dirty.

Installation on a single pipe line:

Hole: Excavation of the correct size of hole is key to the installation of a septic tank. The general rule to follow for a single installation is: 2m long, 1.8m wide and 1.2 deep.  The excavation should be 3m to 4m away from the building. Some septic tanks are also round so you should first look at the diameters of the round tank in order to work out he calculations of the hole. Always leave enough room in the hole  so that you may be ale to work comfortably. Remember that the septic tank will need to be compacted so you need to leave enough room in the hole for compacting purposes.You can make use of tlb’s or manual labour, whichever is cheaper for you.

Golden Tip – Always look for sandy type soil for excavation for installations requiring french drain installations as rocky ground is difficult for excavation. Make sure that no solids are protruding from the cement sand mix. Once you have decided on your excavation site, you may continue wit step 2.

Placing the septic tank into hole: Get a friend to help

Materials needed: 1.6 river and cement mix – this is to be measured for 300mm across the base of the excavated hole.  (in other words:  this should be enough to cover the 300mm base of excavated hole).
3 pvc pipes (should be enough), 3 kimberley sockets, 3 bends and material for backfilling which is generally cement and soil. Purchasing an extra bag of cement if necessary.  Should you prefer to go further away from the house, the piping, parts etc also increases.Make sure that when you insert the septic tank into the hole that it is levelled and bedded correctly..

Tools needed: wrench, pvc glue for joining of the pipes (most important),sand paper to clean joints, water pump to do chipping of corners if needed and a spirit level to keep pipes straight, plumbers soft soap.

Ramming of the pvc pipes: You would need a soap and water solutions. If you have difficulty in fitting a pipe into another pipe, you would have to ram it.

Connecting the septic tank: Find the septic tank inlet:  Find the septic tank toilet outlet. These are usually on the side of the septic tank. On the top you have your breather and the lid of the septic tank (leave these two alone for now). Connect the toilet outlet with a 110mm pvc pipe to the septic tank inlet. Your septic tank outlet is connected to our french drain inlet if you have the necessary permit for a french drain installation.

How does one connect a grease trap for dual pipe line: One should have a grease trap installed on a dual water line, (the water from the bath and the shower called the grey water line). This line is connected to the inlet of the fat trap and the outlet is going to the french drain.

Backfilling: The application of filling the hole once the connection is complete. This is done to stabilise the tank.

Process for backfilling: 1.6 concrete sand mix should be carried out in 300mm thick layers from the base up to 100mm below the top of the septic tank hole with the concrete filled lid in place on the hole. The backfilling material must be slightly moist. This is important. Each 300mm should be densely compacted. This will allow your filling around the tank not to sink. For deeper manholes or where a high water table is anticipated, the backfill mix must be 5% cement and 95% sand or selected granular material.

Please note: Dual Pipe Lines: the application is the same, it is only the connection of the grease trap that differs.

If all else fails, you can always rely on Drain Ratz Plumbers & Builders (sewerage specialists), to come and install it professionally for you

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