T21 waste exemption: recover waste at a waste water treatment works

The T21 exemption allows you to recover wastes such as sewage grits, screenings and sewage sludge at a waste water treatment works.

Applies to England

Types of activity you can carry out

Storing and treating listed wastes on the premises of a waste water treatment works for waste recovery.

Types of activity you cannot carry out

You cannot use this exemption to:

  • treat waste at locations other than at a waste water treatment works
  • treat hazardous waste
  • treat wastes through the waste water treatment process
  • store wastes that will be disposed of through the waste water treatment process
  • store wastes that you will not treat

Type of waste you can treat

The waste codes are listed in the following table. You need to make sure your waste fits within the relevant waste code and description.

Waste code Type of waste
190801 Screenings
190802 Sewage grit (waste from de-sanding) only
190805 Sludge from treating urban waste water
190899 Centrate liquor only
190902 Sludge from water clarification
190903 Sludge from decarbonation
190906 Solutions and sludge from regeneration of ion exchangers
200304 Septic tank sludge
200306 Waste from sewage cleaning
200399 Cesspool waste and other sewage sludge only

You should classify cesspool waste as ‘161002 cesspool waste only’ rather than using the 200399 code. You can further treat partially treated sewage sludges under this exemption. For more information see Waste codes for sewage sludge and sludge containing other materials: RPS 231.

Quantity of waste you can treat

You can treat up to 100,000 cubic metres of imported waste over any 12-month period in addition to any listed wastes you produce on site.

Main conditions

The waste must be stored and treated in a secure location with sealed drainage.


Register this exemption

You must register this exemption with the Environment Agency if you meet the requirements.


Hazardous waste – see How to classify different types of waste.

Sealed drainage – a drainage system with an impermeable surface that makes sure that:

  • no liquid will run off the surface apart from through the system
  • except where they may be lawfully discharged, all liquids entering the system are collected in a sealed sump

Secure – a container, lagoon or other place is secure in relation to waste kept in it if:

  • all reasonable precautions are taken to make sure the waste cannot escape
  • members of the public cannot gain access to the waste
Published 28 April 2014
Last updated 2 July 2021 + show all updates
  1. We have clarified the types of activities you can and cannot carry out, and the types of waste you can treat.

  2. First published.