Septic Tanks & Sewage Treatment Plants – New Rules for Existing Private Drainage Systems in England and Wales

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.

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.