Properties which are not connected to mains drainage, mainly in rural areas, will need to use a private system, most commonly a septic tank or a small sewage treatment plant.  Changes to the regulations governing discharges from these systems have not been well-publicised; often it is not until a property is being sold that problems arise, as this is when drainage investigations are carried out.

So what are the current rules and why is it important that property owners and estate managers should be aware of them?

The law

Discharges to groundwater and surface waters (such as rivers) are regulated by the Environmental Permitting regime, under the Environmental Permitting (England and Wales) Regulations 2016 (EP Regulations 2016).  Small sewage discharges (SSDs) are regulated differently in England and Wales, but for the purpose of this alert we will focus on the rules as they apply in England.

An environmental permit from the Environment Agency may be needed for the operation of the drainage system unless an exemption applies.  The requirements for a SSD from a domestic property were simplified on 1 January 2015, with the introduction of the general binding rules with which discharges must comply to qualify for the exemption.

The general binding rules repeat and expand the requirements set out in the EP Regulations 2016, so it is important to read both carefully.


A SSD of domestic sewage is exempt from the requirement to have an environmental permit, provided it meets a number of conditions including:

  • A general condition that it does not cause pollution of groundwater or surface water.
  • Volume threshold conditions which differ for discharges to surface and groundwater.
  • The discharge meets the location conditions in relation to sensitive and protected sites.

In order to benefit from the exemption, SSDs must not contain any trade effluent, but can include discharges from some small businesses, for example: small hotels, pubs, restaurants and offices.

General binding rules

There are two sets of general binding rules which apply depending on whether the discharge is an existing discharge to groundwater or surface water (before 31 December 2014) or a new discharge from 1 January 2015.  The rules contain a number of provisions including:

  • A new SSD can only be exempt if it cannot reasonably be discharged to the public sewer and for the exemption to apply, new discharges must not be within 30 metres of a public sewer.
  • A small sewage treatment plant must be used to treat the sewage if discharging to a surface water such as a river or stream.
  • Discharges from septic tanks directly to a surface water are not permitted. Septic tanks that discharge to surface waters must be replaced or upgraded as soon as possible; plans should be in place to carry out the work within a reasonable timescale, typically 12 months.
  • For discharge to a groundwater, septic tanks or small sewage treatment plants must be used to treat the sewage and then discharge the effluent (treated liquid) to ground via a drainage field.

Points for owners

When buying a residential property served by a septic tank or sewage package treatment plant specific enquiries must be made to ascertain whether the SSD qualifies for an exemption.  Sellers are under an obligation to give the new owner a written notice stating that a SSD is being carried out and giving a description of the system and its maintenance requirements.

The general binding rules stipulate that where properties with septic tanks that discharge directly to surface water are sold, responsibility for the replacement or upgrade of the existing treatment system should be addressed between the buyer and seller as a condition of sale.  This is because such a discharge does not satisfy the conditions for an exemption and is only allowed to continue where an existing environmental permit is in place.

Responsibility for compliance rests with the “operator” of a SSD who is defined as the person who has control over the operation of the septic tank or sewage treatment plant.  This is not always easy to determine, as this can include someone who uses it even though the system itself (or part of it) is located on neighbouring land, or another person (such as a tenant) who agrees to be responsible for its operation and maintenance.

Owners and estate managers should ensure any systems are checked by a surveyor to confirm they can satisfy the criteria for the exemption, for example, the volume of discharge as well as ongoing maintenance inspections.  A septic tank will need to be upgraded or replaced if it does not meet the standards in the EP Regulations 2016 and if it does not qualify for an exemption, then an environment permit will be needed.  The general binding rules may not be well-known, but as we have shown, you may well be bound by them, so do not get caught out.


If you would like to discuss this topic in more detail, please contact David Hobbs.

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