In attempt to further reduce pollution to the nation’s watercourses from sewage the Environment Agency (EA) brought in new legislation in 2015 that set out strict rules for homeowners who own new and existing off-grid drainage. Since 1 January 2020 these procedures have been enforced by the EA through both civil and criminal sanctions to ensure compliance.

The current levels for fines on the standard scale can range from £200 to £5,000. However, given the importance of environmental issues, environmental statutes now contain provisions stating that the maximum penalty of £50,000 can be imposed in some cases, while fines for offences tried in Crown Courts can, theoretically, be unlimited.

It is quite common for people to be unaware of the drainage systems they have but it is imperative that you understand what you are working with as soon as possible.

First and foremost you will need to identify what system you have and where it is discharging. This can be achieved through on-site investigations, CCTV surveys of underground pipe work and, sometimes, excavations where previous investigations are unable to provide enough information.

Once known, compliance of the system should be cross-referenced with the guidelines. Two additional considerations are that the incumbent system is being maintained within the manufacturer's guidance and that it also complies with the General Binding Rules (GBR) 2015.

While the rules may appear complex, it is vital that they are understood to prevent possible penalties for non-compliance. The key points are:

• Homeowners must know what drainage system they have (type and amount of waste, tank type and discharge point).
  
  
• If the system is not known, they must undertake investigations to identify the system. If the system is compliant with GBR, only ongoing maintenance is required.
  
  
• Non-compliant systems require the homeowner to have a plan in place to rectify the system within a reasonable timescale (typically 12 months).
  
  
• If the system requires replacement or adapting, help must be sought from a specialist drainage contractor or engineer to ensure compliance and suitability for local ground conditions. Planning may be required.
  
  
• If unable to find a solution that fits the GBR rules, due to site limitations, a permit must be applied for from the EA.

If buying or selling a property with a septic tank that discharges directly to a watercourse, you should agree with the buyer or seller who will be responsible for the replacement or upgrade of the existing treatment system. This should be agreed as a condition of sale. Having all of this information to hand prior to putting your property on the market can avoid potential delays in the sales process.

A common misconception is that soakaways are suitable for septic tanks when they actually require a drainage field. Systems that combine foul and rainwater are non-compliant and should be separated. Drainage fields – different from soakaways, which are used for surface water drainage only – are a circuit or perforated pipework beneath ground which allow discharge from the treatment plant to trickle into a wide area of ground and provide secondary treatment.

Where ground conditions are good, the most common fix is to replace existing systems with a small sewage treatment plant (also known as a package treatment plant) and install a drainage field, or discharge into a watercourse. This part-mechanical system treats the liquid so it’s clean enough to go into a river or stream.

For ground conditions that are poor – commonly waterlogged or clay soils – and discharge is not viable, and no watercourse is available, drainage mounds are required. These largely man-made mounds, comprising granular material and soil, create an area with filtration where there currently is not.

Full details of the 2015 legislation can be found on The Environmental Agency website.

Further information

Contact Julian Forshaw

Contact Ben Freeman

Contact Savills Building Surveying or Savills Planning