The Wildfowl & Wetlands Trust (WWT) is calling for a national pilot scheme to be established in the UK by 2025, to make treatment wetlands the default option for meeting new nutrient neutrality targets and to establish and develop an effective market in nutrient trading and offsetting by creating a nutrient offsetting code.

The call comes in a new report from the environmental NGO – Wetlands for Water Quality - Creating and managing treatment wetlands to improve water quality - A Route Map.

WWT is calling for the cleanup of waterways to be assisted through the creation of specialised wetlands at sewage plants, on farms, in housing developments and by roads, alongside stronger regulation and financial penalties for polluters.

Treatment wetlands are wetlands that have been constructed specifically to remove targeted pollutants such as nitrogen and phosphorus from wastewater that comes from sources such as sewage, agricultural waste and landfill. The specially engineered habitats can absorb and break down the pollutants in water in a low maintenance and cost-effective way, so that it comes out clean once it has passed through them.

Key partners identified by WWT from across the UK to facilitate the UK-wide creation of treatment wetlands include the Department for Environment, Food and Rural Affairs (Defra), Environment Agency, Natural England and Ofwat.

Storm Overflows Discharge Reduction Plan “does not adequately tackle the pollution caused by sewage and needs reform”

However, WWT is critical of Defra’s Storm Overflows Discharge Reduction Plan, warning that “ultimately it falls short of matching and overcoming the urgent problems posed by Combined Sewage Overflows (CSOs).

Pointing out that sewage was pumped into waterways for 2.6 million hours in England in 2021, contributing to “rapid declines in the health of our freshwater environments”, the report warns:

“It does not adequately tackle the pollution caused by sewage and needs reform. The Storm Overflows Discharge Reduction Plan relies on self-monitoring by water companies and does not set targets for the action desperately needed to enable a rethink of how storm overflows are managed. The plan will not be reviewed until 2027, which is too late.”

Role of Ofwat “will be crucial in leveraging water industry action”

The report says as the body responsible for economic regulation of the privatised water and sewerage industry in England and Wales, Ofwat “will be crucial in leveraging water industry action.”

However, as no existing plans use treatment wetlands as a default option for treating water, “there needs to be a requirement from Ofwat for them to do so wherever this is feasible.”

The report states:

“Currently, treatment wetlands are not widely adopted by water companies. There’s little incentive to invest outside of protected areas, where water and wastewater companies are legally required to meet lower discharge consents. Therefore, the motivation to invest in treatment wetlands is low. A change in Ofwat guidance could drive this change and lead to significant increase in treatment wetlands.

“Once we have clear mapping of treatment wetland opportunities, water companies can use it to take advantage of these opportunities when treatment wetlands are the most feasible and effective solution.”

“Many water quality problems are result of the age and inappropriate use of water companies’ treatment infrastructure”

The report says that agriculture accounts for almost 70% of England’s land usage and is linked to nearly 40% of factors contributing to water’s failure to meet good ecological status. It goes on to point out that many water quality problems are the result of the age and inappropriate use of the water companies’ treatment infrastructure. The report states:

“Our infrastructure is outdated and can no longer deal with the scale of the sewage problem. The UK’s Combined Sewage Overflow (CSO) system was designed as an emergency measure for use in very heavy rain. It allows untreated sewage to be released into the environment in these exceptional circumstances and requires a permit for use. However, in recent years sewage overflows have been used more frequently, often in dry conditions and without a permit.

“This is due to poor investment in infrastructure. Customers who pay their water bills have provided funding for water companies to make improvements to their service and infrastructure, but the water companies have spent only 68% of this. This means they’re not on track to deliver the Price Review 24.”

Investment in treatment wetlands can save water companies and customers money

According to WWT, treatment wetlands can save water companies and customers money - they have lower outright purchasing costs (CAPEX), lower operational costs (OPEX) and lower carbon emissions.

“There is a huge opportunity for water companies to invest in treatment wetlands on or near wastewater treatment works to treat primary, secondary or tertiary wastewater. This will help them meet legal water quality targets and public demand to reduce their reliance on sewage overflows,” the report says.

Commenting on how treatment wetlands will be financed, the report refers to the UK’s Water Restoration Fund which provides support for water companies to invest in new approaches to water treatment like treatment wetlands. It also flags up the fact that the UK Government has also released £1.6 billion for extra infrastructure investment to address pollution from CSOs.

With regard to the Water Industry National Environment Programme (WINEP) which will see up to £5 billion of investment by water companies in the natural environment between 2020 and 2025, the report says:

“Water companies are also able to finance their own improvements by reducing share dividends on annual profits. It is critical that the cost isn’t passed on to consumers.”

“Evidence shows treatment wetlands have potential to remove up to 90% of nitrogen pollution from agriculture and sewage”

According to WWT, evidence shows that ‘treatment wetlands’ have the potential to remove up to 90% of nitrogen pollution from agriculture and sewage. They could also remove up to 60% of heavy metals from road pollution and trap up to 90% of sediment run-off which can block out light from waterbodies.

With only 14% of England’s rivers in good health and around £21.7 million lost annually due to sickness caused by polluted water, WWT is calling on Government and business to “act now and invest in this pioneering natural solution.”

The report says that widespread use of treatment wetlands could be key to the UK meeting its water quality and biodiversity targets, including helping reduce sewage discharges into rivers and decreasing agriculture pollution.

Dan Roberts, Project Manager (Nature-Based Solutions), from WWT said:

“There is a huge opportunity for a broad range of sectors to improve poor water quality by investing in wildlife-rich treatment wetlands. Ongoing headlines about sewage being dumped in our precious waterways could become yesterday’s news if water companies adopted treatment wetlands and community SuDS schemes as part of a much-needed investment programme.

“There are already government funds available* and scope to reduce share dividends to allow the water industry to invest in this highly effective, low carbon, biodiverse solution to the water pollution crisis, bringing benefits to communities and nature.”

According to the report, treatment wetlands can help reduce the number and impact of highly harmful sewage discharges by being:

• built near houses to treat wastewater at source, removing the need for households to be connected to the main sewer, significantly relieving pressure on our crumbling sewage system.
• constructed between sewage overflow pipes and rivers to clean the dirty discharged water before it enters watercourses.
• installed downstream of discharge points to limit the damage if sewage is released directly into a river.

‘Super’ wetlands can also be built on farms to capture and break down fertilizers, pesticides and sediment which run off fields and buildings and enter waterways when it rain, the report sayss. They can also reduce pollution from roads and landfill sites by being integrated into existing street drainage systems and constructed near dump sites.

“No single organisation will be able to create treatment wetlands on its own”

According to WWT, no single organisation will be able to create treatment wetlands on its own and creating them at the scale and pace needed requires the involvement of national and local governments, the

investment and know-how of businesses, including utility companies (particularly those in the water sector), and a process of co-creation with landowners and local communities.

The environmental organisation wants existing wetland sites that are already improving water quality to be identified and locations for further wetland creation to be prioritised. In the EIP, Referring to the Government’s commitment in the Environmental Improvement Plan 2023 to establish a UK Wetlands Inventory that would map out all existing wetlands and identify actions for their protection, the report says Defra needs to bring existing mapping together and develop this to provide “better data that would increase transparency and make it easier to identify investment opportunities.”

Click here to download the report in full