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Why Does My Septic Tank Smell?

If your septic or AWTS wastewater system is smelling like sewage, it’s because something has gone wrong. The bad smells are caused by gases such as carbon dioxide, hydrogen sulfide and methane escaping the system – the most offensive of which is hydrogen sulfide.

In a healthy septic or AWTS, waste flows through your drains into your system in which it sits in a tank filled with beneficial bacteria. The bacteria produce enzymes which break up the waste, then the bacteria digest the waste and finally the treated effluent and gases are safely discharged from your system. Most bad smells are caused by a disruption to this process.

Here are the causes of bad smells and what your options are.

Septic smells inside the house

  • Blocked drain
    A drain leading to your wastewater system could be blocked and waste is being trapped in the drain instead of passing through to your septic or AWTS. Trapped waste is releasing gases which are passing back up through the drain and into your home.If this is the case you should use a septic safe drain unblocking product to dissolve the blockage without damaging your system, or you could start a treatment routine which would break down the blockage and keep your entire system operating at peak performance. 

  • Insufficient bacteria
    Your septic or AWTS system isn’t digesting waste properly, gases are being produced and are then escaping back up through your drains and into your home.If waste isn’t being digested properly inside your system the most common cause is that there are insufficient bacteria within your tank to properly digest waste. A low bacterial population is due to the temperature, pH, oxygen content or nutrient availability within your tank being out of balance. The fastest way to restore balance to your system is with a biological stimulant based additive that counteracts negative influences and restores the optimal biological conditions for beneficial bacteria to thrive. 

  • Recently pumped out or new system
    Your septic or AWTS tank is new or has been pumped out recently and doesn’t have sufficient bacteria to properly digest waste.After your tank has been pumped out it needs to be seeded with beneficial bacteria so that it can be activated and quickly get back to work. Putting in the right bacteria with the nutrients, minerals and amino acids they need to thrive is the best way to seed and repopulate a recently pumped out or new system. 

  • Broken seal or connection
    There’s an improper seal or broken connection around one of the pipes in your home.Bad smells can escape from broken seals or connections inside your home. One of the most common places is the wax seal around your toilet. Get a plumber in to inspect your pipes and seals and repair anything necessary. 

  • Tank is full
    Your septic tank is full and needs to be pumped out. Your septic tank shouldn’t need to be pumped out frequently. If working correctly, they’re designed to operate for years without any physical intervention. If you haven’t had your tank pumped out for a few years you should get a plumber in to check how full your tank is.

Septic smells outside the house

Slight smells coming from near or around your septic tank are normal, but overpowering bad smells are cause for concern.

  • Blocked septic vent
    Your septic tank vent might be covered. This prevents the gases from escaping effectively and they slowly seep out and linger. You should expect a bad smell coming directly from the vent cover, but it shouldn’t linger outside your home. Check the vents from your septic tank and that they’re unobstructed and in good condition. Renovations and remodeling can damage your vent or prevent them from discharging gases. If your vent looks damaged or obstructed please call a plumber or wastewater technician to inspect your system.

  • Blocked drainage field
    Your leach drain, drainage field or soakaway could be blocked. If you notice that the smell is coming from your leach field there’s an easy solution. Leach drains sometimes have to deal with a lot of fats, oils and greases that can build up and cause blockages. The fastest way to clear these blockages and fix your leach drain is to introduce specialty fat, oil and grease digesting bacteria that will restore your leach drain to peak performance.

  • Septic tank cover not sealed
    Your septic tank cover might not be fastened properly. You should not open your septic tank or remove the cover. The tank is filled with dangerous gases which are highly toxic and should be inspected by a professional. If there are bad smells coming from your septic tank and you think the cover might be the issue, please get in touch with a wastewater technician.