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How To Care For Your Septic Tank System

How to Look After Your Sewage Disposal System?

This will detail a step-by-step approach to maintaining your Sewage Disposal System.

  1. Types of Septic Tanks?
  2. What is a Modern Sewage Disposal System (aka Septic Tank)?
  3. What clogs up a Septic Tank?
  4. What disrupts a Septic Tank?
  5. How to Maintain it?
  6. How often should it be Serviced?
  7. How often should it be Emptied?

  1. Types of Septic Tanks?

    Here is a pamphlet by the NZ Government [1], although it is well behind the times. This is the Auckland Council pamphlet [2]. The The US Government has a better site [3]. And here is an Engineering Site [4].

    Fundamentally there are two types of systems -

    1. Traditional Septic Tank : A traditional, passive system. This may be a single tank or multiple tanks, with optional baffles or obstruction to restrict the flow of solids to the exit point.

    2. Modern Sewage System : A modern system has at least two, often three chambers with an Aerobic and Anaerobic systems. It may have blowers or paddles and a pump.

  2. What is a Modern Sewage Disposal System (aka Septic Tank)?

    A Modern Septic Tank or Sewage Disposal System consists of a container with multiple chambers, most often - three. There are several stages - Link.
    1. The first chamber is the collection centre. There may be a paddle or stirrer here. Here both aerobic and anaerobic bacteria break down suspended solid particles

    2. The second chamber generally supports an Anaerobic process. Air is kept out of the mixture.

    3. The third chamber generally supports an Aerobic process. This may be combined with another chamber.

    4. The fourth chamber generally supports a Clarification process. It is a Holding tank. Almost clean water rises here until a float triggers a Pump to empty the chamber. Generally, a separate float turns off the Pump when the level drops below the Empty Trigger level.

    5. Sometimes there is a feedback of a little water from the third chamber back to the first one. This provides a control mechanism for the whole process.

    6. Sometimes there is a filter just outside the tanks to remove any particles. This has the potential to block the field pipes. It can be a Pleated Cartridge or a Ceramic Stack. You really want to avoid a Ceramic Stack because it requires cleaning from fortnightly to monthly!

    7. The final stage is the field pipes that distribute the water in a designated area. This water is supposed to be very clean, but may still contain microbes. It is a really good source of moisture for your garden. It is completely safe for all bushes and trees, except the plants where the harvest is close to the ground, such as leafy vegetables or strawberries.

    8. Normally, the process is very dumb. But some systems do have a PLC (Programmable Logic Controller) to control the whole process.

    9. Generally, there is an alarm panel, inside the house to let the owner know if the Blower or Pump has failed. Often it is in the Garage, sometimes in the Bedroom. There is a basic flaw in this design. If the circuit breaker trips, then the chambers can overflow into each other requiring a drastic cleaning process.

    10. We have a Home Automation System monitoring and controlling the Sewage System. It monitors the above circuit breaker and sends us an email if the circuit breaker fails. It also kills the power to the system a few hours in the morning and evening, when we may be gardening. This is so we don't get splashed by effluent.

    Note : Not all systems are the same and the designs may vary drastically.
  3. What clogs up a Septic Tank?

    It is obvious that non-Compostable items should not be flushed down the toilet. But it is not necessarily obvious that the following items can clog up the septic tank, which may result in the tank requiring to be emptied -
    1. Hair and Finger Nails - These are both made of keratin which is a strong protein. These may take up to 40 years to decompose.[5]
    2. Fats, Oils and Greases (FOGs) - are less dense than water, so these float to the top. These can accumulate and form a hard crust on the top.[6]
    3. Tampons and Pads - These do not break down in seconds as tissue paper does. These can take from months to years to decades. [7][8]
    4. Condoms and Disposable Nappies - These may take up to 500 years to decompose.[9][10]
    5. Cat Litter - This is heavy and sinks to the bottom of the tank to form a sludge.[11]
    6. Coffee Grounds - These will not decompose in a septic tank. These will also change the pH which may stop the tank from functioning properly. [12]
    7. Dental Floss, Cotton balls and Ear Swabs - These will clog up your septic tank.[13]
    8. Tissues and Paper Towels - While toilet paper is designed to dissolve, other paper products are not. These may take from weeks to five months. [14]
  4. What disrupts a Septic Tank?

    The following items can and will upset the balance of your Septic System. These should never be flushed down the toilet [15][16][17] -
    1. Harsh Cleaning Compounds - Avoid any that say anti-bacterial. Some ECO brands are not good for a Septic Tank.
    2. Strong Chemicals such as Bleach - These will kill the bacteria in the Septic System.
    3. Medications - Many of these contain high concentrations of anti-biotics. These can and will kill the bacteria that need to be present within a septic system.
    4. Fats, Oils and Grease - See the previous section.
    5. Motor Oils, Petrol, Paints and Thinners - Are obviously toxic.
    6. Pesticides, Fungicides and Insecticides - Ditto.
    7. Photographic Chemicals and Solvents - Ditto.
  5. How to Maintain it?

    1. Filter : If there is a filter on the system it should be checked and cleaned regularly. If it is a ceramic stack (or disc) filter, it clogs up faster and must be cleaned more often. A suggested time frame is
      1. fortnightly to monthly for the ceramic filter
      2. monthly to 3 monthly for the cartridge type filter
    2. Pipes : The pipes in the disposal field should be checked regularly for blockage. The pipes should be flushed once a year.
      1. The pipes have regular discharge holes. If no water is coming out of them, then find the first one and squish it with your fingers. This can crumple the deposits.
      2. Flushing involves opening the end cap/plug and letting the effluent discharge. It is easier if you install taps at the end of the pipe(s).
    3. Field : The disposal field should only have small plants or bushes, so remove all large plants and trees regularly.
    4. Mosquitoes : These are not a problem for the system itself. But may be a problem for the householder.
      1. What works best is an outdoor mosquito trap. Note that many products claim to work because they have UV or heat. Neither of these works with mosquitoes. A trap needs to have a lure that, some use a mushroom-based lure. [18].
      2. People have been known to drop frogs in the first chamber. It should be safe for the frog. Maybe it will help.
  6. How often should it be Serviced?

    It should be serviced at least annually. Earlier, under the following conditions -

    1. If it is uncomfortably smelly near the septic tank. It may have a slight odour under normal operation.
    2. If the outflow in the field is not clear.
    3. If an overflow has occurred and you can see waste around the tank. The first signs are normally pieces of toilet paper.
    4. If the toilet bowl smells when it is sparkling clean.
    5. If your local Council requires it. Rodney Council required a six monthly inspection. The Auckland Council is just starting the inspection system and it must be serviced six monthly.[19]. On the Councils site, this is classified as a secondary or tertiary system.[20]
  7. How often should it be Emptied?

    The tank may need emptying anywhere between 3 to 10 years, depending on how many occupants there are, what is being flushed into it, what sort of system it is and what the capacity of the system is. Note that some references are confused as by servicing they mean emptying ![21][22].

    However, if you are getting your tank services regularly, the technician will recommend a clean when it is necessary.


  1. The Story of Your Septic Tank System
  2. Tips for maintaining your septic tank
  3. Types of Septic Systems 1
  4. Types of Septic Systems 2
  5. Can You Compost Nail Clippings?
  6. Fats Oils and Greases
  7. Flushing Tampons down the Drain
  8. Top 5 Items to keep out of Your Septic System
  9. Sanitary Insanity : Tampons..
  10. Environmental Impact of Nappies
  11. Why Kitty litter is deadly for your Septic System
  12. Avoid Putting Coffee Grounds in your Septic System
  13. Never Flush These Things
  14. How long does it take Paper Towels to break down?
  15. Choosing Septic Safe Laundry Soap..
  16. Top 10 products to avoid using when you have a septic tank
  17. Top 5 Items to keep out of Your Septic System
  18. Pestrol Terminator
  19. How often Should I get my Septic Tank Serviced
  20. Akl Council : Rules for onsite wastewater systems
  21. How often should my septic tank be emptied?
  22. How often should Septic Tank be Emptied?

A Step-by-Step Process to Care for your Septic Tank System

Disclaimer : I am not associated with any of these companies. I do not receive any financial incentives from any of them. These are my honest views based on experience and research.