27 January 2022

Why Does my Septic Tank Smell?

Does your septic system smell really bad? Are there are foul odours around your leach drains, around the tank itself or inside your home? Well, it's probably time to give your septic system a bit of attention.

Bloo Septic Tanks

Blog Tile Jan Septic 3

Your septic system puts up with a fair bit of crap (excuse the pun!) and the occasional bad smell from it is nothing to worry about. But if it’s smelling all the time, you can’t ignore it.

The good news is that there are a few common causes of smelly septics, and none of them are too hard to fix.

So, how does a Septic System Work?

Septic systems aren’t rocket science, so before we start looking at problems and cures, let’s just take a moment to make sure we’re on the same page about how the concept works:

All wastewater from your toilets, bathroom, kitchen, and laundry is collected in pipes which flow into your septic tank. Any oils and fats rise to the top; the rest of the solids sink to the bottom of the tank where they are broken down into sludge by good bacteria. The remaining water, which is called effluent, flows out to your underground soakage drains where it disperses into the ground.

That’s it in a nutshell.

A healthy septic that’s working well should be pretty much odour-free. And if you’re like most of us, when our septic systems are working well, we just leave them to do their thing. However, when something gets out of balance, the smells can be fairly hideous. Not to mention downright embarrassing if you’ve got friends coming over for dinner!

Common Causes of Smelly Septics

  • A Full Tank

How long is it since you had your tank emptied? A healthy septic should only need emptying every few years, but if it’s been a while, this might be the problem.

  • Chemical Imbalance

The chemistry inside your septic system has to be kept in balance for it to do its job properly. This means a maintaining a PH level of between 6.8 and 7.6. You’ll know if the acid levels inside your septic get too high because it’ll produce an odour like rotten eggs.

Chemicals can be added to your tank to restore the correct balance of bacteria, so talk to your local plumbing service about how to go about this.

  • Blocked Drains

If one or more of the drains carrying waste into your tank are blocked, the trapped water could be sitting in the pipes, and causing gasses flow back up the pipes and into your home.

There are a number of products which can be used to safely unblock clogged drains. However, depending on the size of the blockage, you might be best to get a plumber clear it.

  • Drains are too Dry

Your drains have a U-shaped bend in them that’s meant to hold water and prevent gasses from coming back into your home. If this trap has dried out, this might be the reason you can smell sewerage inside your home.

Flush all of your toilets regularly, even if they’re not being used. Pour a few cups of water down sinks, shower grates and floor waste traps that aren’t regularly used too - ensuring that there’s water in the trap will help to prevent this backflow of smells from your septic system.

  • Tank Cover Issues

If your septic tank cover isn’t fitted correctly, or if it has a hole in it, this could allow smells to escape from the unit. Unless you’re a qualified plumber, don’t try and remove the cover yourself. Instead, call your local plumbing service and get a professional in to help.

  • Blocked Vent Stack

Your sewer system will have one or more integral vent stacks built into it. Normally you can see a pipe running from a sewer pipe up the wall of your home, or a small pipe coming out through the roof. If the vent stack has become blocked, this could cause gasses to accumulate inside the system and result in foul smells inside your home.

  • Blocked Soakage Drains

If your soakage system isn’t working at peak performance, the run-off area may start to smell. A few tell-tale signs of blocked leach drains are:

    • taller, greener grass around the lines
    • an unusually large accumulation of black sludge (biomass) in the lines
    • sinking soil around the lines
    • pooling of water in the lines

Blocked soakage drains can cause effluent to back up in the system, and the result is sluggish draining of toilets and sinks inside.•

Slight septic odours don’t necessarily mean there’s a big problem with the system.

If your home is located in a valley or a heavily forested area, there simply mightn’t be enough air movement to successfully disperse the odours from around your home. In this instance, you can consider extending the vent stack or installing a carbon filter to your system to help eliminate the odours.

Can Cleaning Agents Harm my Septic System?

Yes! Some chemical cleaners can wreak havoc with the good bacteria that’s needed to break down the sewerage in your septic tank.

Here are a few common cleaning products that we recommend you DON’T use if your home is on septic:

  • Chlorine Bleach - yes, it has awesome antibacterial properties, but if you’re using bleach regularly, it’ll be devastating for the bacteria in your septic system.
  • Antibacterial Cleaners - regular use of antibacterial soaps isn’t good for the bacteria in your tank. We recommend using a mild soap for showering and handwashing, followed by an air-drying antibacterial gel, if you’re concerned about killing germs.
  • Detergents - a lot of regular detergents and laundry powders contain phosphates and other nasties which can have a negative impact on your tank’s bacterial balance. Choose ‘septic-safe’ washing powders and detergents wherever possible.

There are plenty of cleaning agents available that are perfectly safe for your septic system. And of course, grandma’s old trick of a few tablespoons of bi-carb soda followed by half a cup of vinegar to clear smelly sink drains always worked a treat!

What Shouldn’t Go into my Septic?

Generally, common sense tells us what we should and shouldn’t put down the drains and into our septic systems. But nevertheless, we’ve decided to jot down a few of the things that should NOT be flushed into your tank:

  • Excess fat or oil
  • Disposable nappies or personal hygiene products
  • Disposable wipes (even if they say they’re flushable)
  • Kitty litter
  • Cigarette butts
  • Paint

Why Does my Septic Smell more when it’s Raining?

There’s a simple explanation for this: when it’s raining the air pressure is low and any gasses that are being released from your septic system will hang around closer to the ground where you’ll be more likely to smell them.

Who can I get to Service my Septic System?

Servicing a septic is no job for a novice, and all maintenance tasks must be carried out by a qualified professional in accordance with council regulations.

Here are a few local service agents that we recommend:

Devonport Septic Tank Cleaning

Budget Pumping

All Pumping Solutions Tasmania