The Environment Agency has issued new guidance on when water companies can temporarily discharge water unfit for supply from water treatment works and supply assets to surface waters.

The Agency has published a regulatory position statement (RPS) setting out when water companies in England can temporarily discharge water intended for drinking water supply from water treatment works and water supply assets.

The RPS does not change the legal requirement to have and comply with a water discharge activity permit. However, the Environment Agency will not normally take enforcement action against water companies who do not comply with these legal requirements if they meet the requirements set out in the RPS provided that:

• the activity meets the description set out in the RPS
• the company complies with the conditions set out in this RPS
• the activity does not cause (and is not likely to cause) pollution of the environment or harm to human health
• the activity does not cause significant adverse visible effect on the receiving water, the bed of the watercourse or any plants or animals within the watercourse
• the activity does not adversely affect the countryside or places of special interest

The RPS applies to water which is intended, but unsuitable, for supply - also known as ‘out of specification waters’ that come from water treatment works (WTW) and water supply assets.

Out of specification waters cannot be used in drinking water supply so have to be discharged to the surface waters.

Conditions water companies must comply with set out in the RPS include:

• discharge only to surface waters as defined by paragraph 2 of Schedule 1 to Water Framework Directive Regulations 2017
• have a method statement that minimises the risk of pollution to the receiving watercourse, such as how to prevent scour or erosion and how to manage silt
• dechlorinate the discharge
• make sure the discharge is between pH 6 and pH 9
• monitor the discharge at least daily for turbidity, pH and, if applicable, total available chlorine, total iron and total aluminium
• monitor the receiving water at least daily, as far as is reasonably practicable
• include the discharge in a permitting plan agreed by the Environment Agency if the discharge has been subject to treatment, such as chemical dosing or chlorination
• keep records for 2 years showing compliance with the RPS and make these records available to the Environment Agency on request.

The water company must also notify tell the Environment Agency if:

• the pH is outside of the range 6 to 9
• the total available chlorine is greater than 0.05mg/l
• the total iron is greater than 2mg/l
• the total aluminium is greater than 1mg/l
• there are dead or distressed fish, other animals or plants in the area of the discharge
• there is appreciable deposit of solid material
• there is appreciable discolouration of the receiving water
• there is scouring of the bed or banks of the watercourse
• the discharge occurs or may occur on more than 3 consecutive days or has occurred on more than 10 days in a calendar year

In addition, the water companies must not:

• pollute any surface waters
• discharge within or 500 metres upstream of, places of special interest unless agreed by the Environment Agency
• cause or contribute to, the failure of Environmental Quality Standards (EQS).
• cause erosion or scour of the watercourse bed or banks
• increase the spread of non-native invasive species, parasites or disease.
• cause or contribute to flooding in the downstream catchment
• carry out the activity on more than 7 consecutive days unless agreed by the Environment Agency

The Environment Agency will review the RPS by 1 April 2026. Click here for more information