Guidance

Using waste codes for sludge materials: RPS 231

Updated 12 September 2024

Applies to England

This regulatory position statement (RPS) does not change your legal requirement to comply with an environmental permit for a waste operation or a relevant waste exemption when you treat, store or spread sewage sludge and septic tank sludge to land. 

However, the Environment Agency will not normally take enforcement action against you if you do not comply with this legal requirement provided that:

• your activity meets the description set out in this RPS

• you comply with the conditions set out in this RPS

In addition, your activity must not cause (or be likely to cause) pollution of the environment or harm to human health, and must not:

• cause a risk to water, air, soil, plants or animals

• cause a nuisance through noise or odours

• adversely affect the countryside or places of special interest

Activity this RPS applies to

This RPS applies to some exemptions and permits for the treatment, storage and landspreading of certain waste types not covered under them. The exemptions and permits this RPS applies to are: 

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

• S3 waste exemption: storing sludge

• SR2010 No 17: storage of waste to be used in land treatment

• SR2010 No 5: mobile plant for the reclamation, restoration or land improvement

• SR2010 No 6: mobile plant for landspreading of sewage sludge

If you operate under a bespoke permit, you cannot use this RPS.

Conditions you must comply with

You must only use the additional waste types given in this RPS for sewage sludge if they arise from these corresponding types of treatment:

• anaerobic treatment (anaerobic digestion) of sludge with the addition of treated sewage effluent produced at the sludge producer’s waste water treatment plant
• aerobic treatment of sludge with non-waste straw, wood or other non-waste plant tissue (composting)
• stabilisation of sludge using non-waste lime
• sludge mixed with non-waste straw, non-waste wood or other non-waste plant tissue material
• sludge dewatering and storage with the use of chemical additives to aid dewatering

You must only use the additional waste types given in this RPS for septic tank sludge if they arise from these corresponding types of treatment:

• anaerobic treatment (anaerobic digestion) of septic tank sludge
• aerobic treatment of septic tank sludge with non-waste straw, wood or other non-waste plant tissue (composting)
• stabilisation of septic tank sludge using non-waste lime
• septic tank sludge mixed with non-waste straw, non-waste wood or other non-waste plant tissue material
• septic tank sludge from dewatering and storage with the use of chemical additives to aid dewatering

You must:

• have registered the relevant exemption, if you are using this RPS in relation to an exemption

• operate under the relevant standard rules permit, if you are using this RPS in relation to a standard rules permit

• comply with all other requirements of the relevant exemption or permit as appropriate

• comply with all the requirements of the Sludge (Use in Agriculture) Regulations 1989 (SUiARs)

• keep records for 2 years from the date of the last use of the RPS to show that you have complied with this RPS and make these records available to the Environment Agency on request

You must not:

• use the waste code 19 08 05 to describe waste other than untreated sludge from treatment of urban waste water

• use the waste code 20 03 04 to describe waste other than untreated septic tank sludge

Things to note

Sludge and septic tank sludge have the same meanings in the RPS as given in the SUiAR.

“Sludge” means residual sludge from sewage plants treating domestic or urban waste waters and from other sewage plants treating waste waters of a composition similar to domestic and urban waste waters.

“Septic tank sludge” means residual sludge from septic tanks and other similar installations for the treatment of sewage.

Waste codes you can use for sludge

You can use these waste codes and descriptions if you hold and comply with SR2010 No 5 as table 2.3, SR2010 No 6 and SR2010 No 17:

• 19 02 06 Sludge from the dewatering of sludge with the use of chemical additives
• 19 02 06 Sludge stabilised using non-waste lime
• 19 02 06 Sludge mixed with non-waste straw, non-waste wood or other non-waste plant tissue material
• 19 05 03 Compost from aerobic treatment of sludge with non-waste straw, wood or other non-waste plant tissue

You can use 19 06 06 Digestate from anaerobic treatment of sludge with the addition of treated sewage effluent produced at the sludge producer’s waste water treatment plant if you hold and comply with SR2010 No 6 and SR2010 No 17.

Sludge waste codes you can use if you have registered a S3 waste exemption

You can use these waste codes and descriptions for sludge if you have registered a S3 waste exemption:

• 19 02 06 Sludge stabilised using non-waste lime
• 19 02 06 Sludge from the dewatering of sludge with the use of chemical additives
• 19 02 06 Sludge mixed with non-waste straw, non-waste wood or other non-waste plant tissue material
• 19 05 03 Compost from aerobic treatment of sludge with non-waste straw, wood or other non-waste plant tissue
• 19 06 06 Digestate from anaerobic treatment of sludge with the addition of treated sewage effluent produced at the sludge producer’s waste water treatment plant

Sludge waste codes you can use if you have registered a T21 waste exemption

You can use these waste codes and descriptions for sludge if you have registered a T21 waste exemption:

• 19 02 06 Sludge stabilised using non-waste lime
• 19 02 06 Sludge from the dewatering of sludge with the use of chemical additives
• 19 02 06 Sludge mixed with non-waste straw, non-waste wood or other non-waste plant tissue material
• 19 05 03 Compost from aerobic treatment of sludge with non-waste straw, wood or other non-waste plant tissue
• 19 06 06 Digestate from anaerobic treatment of sludge with the addition of treated sewage effluent produced at the sludge producer’s waste water treatment plant
• 19 12 12 Wastes from mechanical treatment of sludge other than those mentioned in 19 12 11

Septic tank sludge waste codes you can use if you have registered a S3 waste exemption

You can use these waste codes and descriptions for septic tank sludge if you have registered a S3 waste exemption:

• 19 02 06 Septic tank sludge stabilised using non-waste lime
• 19 02 06 Septic tank sludge from the dewatering of septic tank sludge with the use of chemical additives
• 19 02 06  Septic tank sludge mixed with non-waste straw, non-waste wood or other non-waste plant tissue material
• 19 05 03 Compost from aerobic treatment of septic tank sludge with non-waste straw, wood or other non-waste plant tissue
• 19 06 06 Digestate from anaerobic treatment of septic tank sludge

Septic tank waste codes you can use if you have registered a T21 waste exemption

You can use these waste codes and descriptions for septic tank sludge if you have registered a T21 waste exemption:

• 19 02 06 Septic tank sludge stabilised using non-waste lime
• 19 02 06 Septic tank sludge from the dewatering of septic tank sludge with the use of chemical additives
• 19 02 06 Septic tank sludge mixed with non-waste straw, non-waste wood or other non-waste plant tissue material
• 19 05 03 Compost from aerobic treatment of septic tank sludge with non-waste straw, wood or other non-waste plant tissue
• 19 06 06 Digestate from anaerobic treatment of septic tank sludge
• 19 12 12 Wastes from mechanical treatment of septic tank sludge other than those mentioned in 19 12 11

When you must check back

The Environment Agency will review this RPS by 30 September 2026.

The Environment Agency can withdraw or amend this regulatory position before the review date if they consider it necessary. This includes where the activity that this RPS relates to has not changed.

You will need to check back from time to time, including at and before the review date, to see if this RPS still applies.

This RPS remains in force until it is removed from GOV.UK or is otherwise identified as having been withdrawn.

You can subscribe to email updates about this RPS. These will tell you if the RPS has changed and when it has been withdrawn.

If you cannot comply with this RPS

If you operate under this RPS but can no longer comply with it, you must:

• stop the activity to which this RPS relates

• tell the Environment Agency immediately by emailing enquiries@environment-agency.gov.uk and put ‘Using waste codes for sludge materials: RPS 231’ in the subject

Contact the Environment Agency

If you have any questions about this RPS email enquiries@environment-agency.gov.uk and put ‘Using waste codes for sludge materials: RPS 231’ in the subject.