How to design a septic tank?
All site survey results affect system design, from the installation depth of the tank to the required size of the drainage site. Now is the time to find a septic tank that meets all the criteria.
Before considering a wide range of septic tanks, there are some calculations and considerations to help you find a suitable solution. These include:
Septic tank sizing is usually categorized first by capacity and then by the number of people who can serve the septic tank, so a little care should be taken.
You determine the minimum population size of your property (calculating not only the number of people currently living there, but also the potential population of your property) and the amount of sewage that your property can produce. You need to be able to do this, which will help you determine the capacity you need.
Remember to choose the best tank for your tank size. Also consider the simplicity and cost of installation, aesthetic aspects after installation, and operation and maintenance. Septic tanks usually consist of a series of trenches containing perforated pipes and gravel and are installed under soft landscaping areas such as lawns. Determining the size required for the system depends on both the size of the property/the number of residents and the results of the percolation test.
Septic tank installation stage
Check the tank for damage. Tanks are usually thoroughly tested and inspected prior to shipment, but it is not uncommon for them to be damaged during transportation and unloading. Most manufacturers do not accept claims for damages after the tank has been installed, so be sure to inspect the tank thoroughly upon arrival.
Make sure you have the correct inversion depth
During the site visit and planning stage of the project, it is necessary to confirm the depth of the inflowing pipeline and order a tank with the appropriate reversal height. However, it is worth rechecking to make sure that the physical tank provided remains connected to the existing piping and remains within the maximum allowable depth.
Installation of a tank
Check the planned installation location against the guidelines in the installation manual, as additional tank requirements and minimum clearances may be recommended.
Excavate the hole
Make sure it is large enough for the tank and any recommended backfill, then install the right type of base (often a concrete one) for the tank to sit on.
Consider drainage falls
This should have been part of your planning already, but it is worth double checking, especially for a gravity system. Typically these will be 1 in 60/70 between the house and tank, and a maximum of 1 in 200 for a drainage field.
Place the tank
Carefully lower the tank into the hole, using the recommended lifting system, while checking that the inlet and outlet orientation is correct and ensuring the tank is level.
Use correct backfill
Concrete,gravel, or sand is the most common recommendation, but check the owner's manual for manufacturer recommendations and follow the steps to add backfill material in the field.
Install inlets and outlets
If everything goes according to plan, it should be an easy task, but if you are not sure, you should consult a qualified plumber.
Installation of septic tank
Please read the dedicated guide for installing septic tank drainage panels.
Install cover and frame correctly
Manufacturers always expect tanks to be installed in non-traffic locations. If not, it is highly recommended to consult a structural engineer before installing the system.
Take into account ventilation precautions. This is often overlooked, but it is important to make sure that the system is well ventilated to avoid odour problems in the area. If you are not sure which arrangement is best for your area, please contact technical team of the manufacturer.