Guidance

Treating and using water containing suspended solids at construction sites: RPS 235

Updated 23 October 2024

Applies to England

This regulatory position statement (RPS) does not change your legal requirement to get an environmental permit for a waste operation, when you store, treat and use waste water containing suspended solids at construction sites. 

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 storing, treating and using waste water containing suspended solids (excluding concrete or grouts) within a construction site before use or disposal.   

Conditions you must comply with

You must:

• follow a method statement which minimises the risk of pollution, including but not limited to control measures, monitoring and inspection, staff training and incident response planning

• keep records for 2 years from your last use of this 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 waste water containing suspended concrete or grout.

Storage

You must:

• securely store the water containing suspended solids – secure means that the water cannot escape, and unauthorised people cannot access it

• contain the water before treatment and use, for example through use of an impermeable settling tank, engineered settlement lagoon or leakproof skips

• maintain a freeboard of 10% of the capacity of the tank, engineered lagoon or leakproof skip to prevent overtopping

You must not:

• store more than 30m³ of water containing suspended solids at any time in any single location on the construction site  

Treatment 

You must only treat water containing suspended solids by:

• filtration, settlement lagoons or physical dewatering, for example in a settlement tank, silt press or other specialised treatment system 

• using products to solidify water containing suspended solids for use or transfer from the construction site  

You must operate and maintain specialised treatment systems using trained operatives in line with the manufacturer’s instructions.

You must not use any chemicals or flocculants other than products to solidify water containing suspended solids.

Use

You must not use:

• treated water containing suspended solids to suppress dust within a groundwater source protection zone 1, or within 50m of a point from which water is abstracted for domestic or food production purposes including private drinking water supplies  

• more water than necessary to suppress dust – examples of excessive use would include use on already wet ground, water ponding on the land and runoff from the location where the water is being used 

• water containing suspended solids from excavations at sites known or suspected to be contaminated by oil, metals, hydrocarbons, solvents, pesticides or other polluting substances 

• treated water containing suspended solids other than to wash equipment, make cement, mortar, and so on or for dust suppression  

Locations

You must not carry out activities associated with storing, treating or using water containing solids within 10m of any watercourse and within 50m of:  

• Sites of Special Scientific Interest 

• Special Areas of Conservation (SACs) including proposed SACs 

• Special Protection Areas (SPAs) including potential SPAs 

• Ramsar sites – wetlands of international importance (both listed and proposed)

• Marine Conservation Zones

• other nature conservation sites, such as ancient woodlands and local and national nature reserves – check the map 

• local wildlife sites 

Discharges

You must keep records demonstrating lawful discharge of waste waters to groundwater, surface water or sewer.

Things to note

If the water under this RPS cannot be used on the construction site then it must be legally discharged or transported off-site for treatment and disposal.

Before you discharge water containing suspended solids you must take certain actions first. If you discharge to:

• the foul sewer – get the sewerage undertaker’s consent

• surface water – get a water discharge activity permit, unless you can comply with our RPS on temporary dewatering from excavations to surface water

• to ground – get a groundwater activity permit unless you qualify for a groundwater activity exclusion after assessment from the local Groundwater and Contaminated Land team

You must comply with your waste environmental permit or waste exemption if you want to use waste dried solids fines on your construction site.

When you must check back

The Environment Agency will review this RPS by 30 June 2027.

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.

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

This RPS remains in force until it is removed from GOV.UK or is otherwise identified as having 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 wastetreatment@environment-agency.gov.uk and include ‘RPS 235’ in the subject

Contact the Environment Agency

If you have any questions about this RPS email wastetreatment@environment-agency.gov.uk and include ‘RPS 235’ in the subject.