Cesspit and cesspool services covering Kent and East Sussex

Rules for Existing Private Drainage Systems in England and Wales

New rules for dwellings served by a septic tank or sewage treatment plant came into force in January 2017.


Septic tanks are very common in rural situations and most homeowners find them a relatively easy solution to the problem of dealing with waste water and sewage where no mains drainage is available – so long as they are regularly emptied and maintained.

However, if you have a dwelling in England or Wales which is served by a private septic tank or private sewage treatment plant (STP), you will need to ensure that this is compliant with The Environmental Permitting (England and Wales) Regulations 2016. These came into force on 1st January 2017 and incorporate the earlier General Binding Rules for Small Sewage Discharges.

These regulations must be complied with by 1st January 2020 (or sooner if pollution is already occurring or in the case of dwellings with private drainage systems which are to be sold).

In order to understand what action, if any, needs to be taken, it is important to understand the differences between the two most common forms of private foul drainage system, septic tanks and sewage treatment plants.

Septic tanks

A septic tank is a simple tank built into or buried in the ground. It has an inflow of sewage from the house and an outflow from the tank. The principle is that solid matter settles within the tank and only liquids flow out. A 2010 study by Natural England found that around 80% of septic tanks were not working satisfactorily. Furthermore, the outflow drain from many older septic tanks leads straight in to a field drain and thereby eventually into an open watercourse or, indeed, directly into a ditch, stream or river. This arrangement is no longer permitted and remedial action will need to be taken no later than 1st January 2020.

Sewage Treatment Plants (STPs)

STPs or package plants are prefabricated, mechanical plants which operate like a mini sewage works. They incorporate pumping and aeration equipment, which ensures the better circulation and breakdown of the sewage. Consequently, effluent from package treatment plants should be much cleaner than that from septic tanks and can usually (subject to an Environment Agency permit where appropriate) be discharged to surface waters such as rivers or streams.


England: as long as the General Binding Rules are complied with, most private domestic septic tanks and STPs will not need to have a formal permit or to be licensed or registered.

Wales: It is already a legal requirement to register septic tanks and STPs in Wales. Guidance for this process is available on the Natural Resources Wales website. Implementation is currently “light-touch” with no experience of NRW undertaking inspections or questioning the applications.


For domestic sewage only, and outside Designated Sensitive Areas (DSAs), these permit:

  • The discharge of up to 5m3 per day to watercourses, but only from a sewage treatment plant.
  • The discharge of up to 2m3 of effluent per day into the ground (i.e. from a septic tank). (A typical dwelling is likely to produce just under 1m3 per day of effluent.)

However, it will not be permitted to discharge effluent from septic tanks (as opposed to STPs) directly or indirectly into drains, ditches or other watercourses after 1st January 2020.


Septic Tanks

Check that each tank:

  • is discharging to the ground only.
  • is discharging domestic sewage only.
  • is not discharging more than 2m3 per day.
  • is regularly de-sludged by a registered waste handler.
  • has sound, properly fitting lids and covers.
  • if installed prior to 1st January 2015, is more than 50 m from any well or borehole and is outside a Special Protection Zone. o if installed after 1st January 2015, is also outside any DSA.
  • shows no evidence of overflowing or pollution. (If there is effluent visible in the vicinity of your tank, your tank needs to be emptied, or your ground discharge is not working properly – or both. Surface run-off of effluent is likely to end up in a watercourse which is illegal.)

If all of the above are satisfied, no further action needs to be taken.

However, if the tank discharges to a ditch, stream, river or lake, or via field drains to any of these, remedial action is needed prior to 1st January 2020 to ensure compliance. Assuming a mains connection is not practicable, this can take one of two forms: the formation of a suitable drainage field or ‘infiltration’ system; or installation of a new private sewage treatment plant.

Sewage Treatment Plants

Check that:

  • working parts are suitably serviced –advisable to have a management contract with a specialist. o the plant is regularly de-sludged by a registered waste handler.
  • there is no evidence of overflowing or pollution.
  • it is outside a DSA
  • it is handling domestic (ie not commercial) sewage only.
  • it is not discharging more than 5m3/day.
  • it was installed in accordance with the planning and building regulations in place at the time (pre 1983 installations are deemed to comply automatically with this). o it was installed pre 1st January 2015

If all these matters are satisfied, the system is compliant and no further action needs to be taken. If it was installed after 1st January 2015, it is deemed to be a new discharge. If the required planning permission and/or Building Regulations approvals were not obtained at the time, they must be obtained retrospectively


The construction of drainage fields and infiltration systems is generally deemed not to require planning permission, outside DSAs. However, these operations will certainly be subject to The Building Regulations. The installation of a septic tank or STP in a new location is likely to require full planning permission. Replacement of one tank by another, or replacement of a septic tank with a STP in the same position, may not. It is prudent to write to the local planning authority setting out brief details of the proposal, or making a pre-application submission enquiry, to clarify the need for planning.


These include:

  • Source Protection Zones (SPZs) for groundwater. These are areas in and around commercial water supply resources. The location and extent of these is published by the Environment Agency.
  • land within 50m of a private water supply used for human consumption.
  • Special Areas of Conservation, Special Protection Areas, RAMSAR Site or biological SSSIs. o chalk rivers
  • aquatic nature reserves
  • designated bathing waters
  • freshwater pearl mussel sites
  • ancient woodland

In, and within certain distances of these areas, The General Binding Rules do not apply and EA permits are required for sewage discharges to surface waters and discharges made into the ground after 1st January 2015.


Where over 5 cubic metres of effluent per day is to be discharged, and/or the sewage is commercial, an exemption under The General Binding Rules is not available, even outside DSAs. It will be necessary to apply to the Environment Agency for a Standard Rules Permit to Discharge.


The EA have indicated that they wish to work with relevant parties towards a cleaner environment, rather than run an aggressive regime of enforcement and sanctions. It would seem sensible for property owners to concentrate, in this order, on:

  • identifying the positions and types of all private discharges
  • making good any obvious leaks or overflows, broken covers, lids and other parts
  • ensuring regular desludging of all tanks and plants by registered waste carriers
  • ensuring regular maintenance contracts are in place for STPs
  • planning and budgeting for upgrades and replacements
  • prioritising work on any systems which are causing problems, likely to be sold or high risk


Purchasers usually insist that a private septic tank discharging to a watercourse is made compliant by the vendor prior to sale. If not, substantial reductions from the purchase price are being agreed on the basis that the purchaser will take on this impending liability.

After 1st January 2020, a declaration that you have a septic tank discharging into an open watercourse will effectively be an admission that you have a non-compliant private sewage system and are committing an offence.