Private treatment systems

Bacteria from sewage pollution can cause water quality to drop in rivers and at beaches, impacting people enjoying these amenities.




If you’re not connected to the main sewer and use a private treatment system, such as a cesspit or septic tank, it’s your responsibility to ensure you’re not polluting the environment or causing an issue to public health.

The following advice will help you protect your environment and prevent a costly fine.


Which sewage system are you on?



  • empty it when full (usually every six-12 months) using a registered waste carrier who has a waste disposal license
  • you’re ultimately responsible for disposing of your waste safely – if it’s not, you could be prosecuted
  • fix any leaks immediately
  • fit a high-level alarm so you know when your cesspit/cesspool needs to be emptied (before it overflows).

Septic tank


  • you’re responsible for disposing of your waste  safely – if you don’t, you could be prosecuted
  • inspect it regularly
  • fix any faults or problems immediately
  • protect the draining field – don’t dig, drive, plant or build on it. 

If you spot any of these signs, contact an Environment Agency registered contractor as soon as possible:


  • drains slow to clear or toilets backing up
  • spongy ground or lush vegetation/grass growing above the drainage field or soak away
  • dark, smelly liquid at the discharge pipe. If you have consent to discharge are you still discharging the consented volume?

Systems’ dos and don’ts



  • call a professional if you spot sewage smells or pools of water near systems, or you see sludge, foam, loo paper or grey fungus in local watercourses
  • inspect the system once a month and keep records of them
    secure all covers
  • only put the three ‘Ps’ down your system — pee, poo and toilet paper
    use natural cleaning products such as bicarbonate of soda, vinegar and lemon juice. They won’t kill the bacteria that breaks down the sewage
  • empty your tank regularly so it doesn’t leak or overflow and use a registered waste carrier.


  • put unflushables such as wipes, nappies, paper towels, fats, oils or greases down the sink or toilet
  • use caustic solutions to unblock drains – use hot water or drain rods
  • let rainwater enter the system – it can cause overfilling which dilutes the natural bacteria preventing the system working properly
  • enter a septic tank or cesspit/cesspool – dangerous toxic gases build up which can be fatal
  • use harsh cleaning products such as bleach, or use sparingly, they can kill the bacteria breaking down the sewage
  • block air vents.

Effects to your pocket and the environment


  • maintaining your sewage system will save you money in the long run (a few hundred pounds per year to maintain is better than replacing a system which could cost thousands)
  • if your system’s unusable, it could lower the value of your property
    if your property’s a holiday let, poor maintenance and bad smells can be bad for business
  • lack of maintenance, could result in environmental pollution, impacting the water quality in local rivers and bathing and shellfish areas
  • poor water quality can affect tourism and reduce income for local businesses in your area
  • untreated sewage is brimming with bacteria and viruses, as well as nitrogen and phosphorous
  • if sewage enters the environment before being treated, it could contaminate surface and groundwater, posing a risk to drinking water
  • pollutants can harm local wildlife, impacting flora and fauna and don’t fix a fault, you could face a fine of up to £50,000
  • you have a social and legal responsibility to maintain your sewage system
  • you must comply with the Environment Agency’s ‘general binding rules’ and/or the conditions set out on your permit.