More than £100bn needed to tackle drainage issues

More than £108 billion will need to be spent on drainage upgrades and wastewater management by 2050, according to water and sewerage companies.

Of that, at least £40 billion will be spent tackling issues with combined sewer overflows (CSOs).

The figures are revealed within the final Drainage and wastewater management plans (DWMPs), published this week by English companies. The plans are designed to meet new regulatory and legislative environmental requirements as well as for the sector’s statutory duties.

Each plan divides investment needs into five-year asset management periods (AMP) from 2025 to 2050 and spending will be will subject to approval by Ofwat at price reviews.

Investment is heavily weighted towards tackling combined sewer overflows (CSOs) to reduce the risk of harm to waterways. Companies with the highest number of CSOs within their sewer networks anticipate spending significantly more to meet new targets than those with fewer overflows.

Government set objectives for all companies to drive down reliance on CSOs to improve the health of rivers and streams by 2050. Initial focus will be on overflows in sensitive catchments, or near bathing waters.

Common themes throughout plans are the need to prioritise nature-based solutions and catchment approaches to remove or divert surface water from sewer networks to prevent them being overwhelmed.

DWMPs included unconstrained ambition as well as lowest cost interventions, which would involve mostly grey engineering rather than multi-benefit blue-green schemes.

Utility Week has broken down what the companies want to spend over the coming decades.

Anglian’s sewerage network is made up of 76,000 km of pipes, 1,100 treatment plants processing around 927 million litres of wastewater each day.

How much? £5 billion over 25 years

Action on CSOs: £1.5 billion

The company has laid out its intention of having zero serious pollution incidents and a 45% reduction in all pollutions by the end of the current investment period. It has already surpassed its 2025 goal to lower annual average spills from overflows to 20, three years ahead of that target it has an average of 15 spills.

It aims to remove 25% of surface water from wastewater networks across the majority of its catchments, rising to 50% in areas with high risk of pollution contamination.

Northumbrian The company’s wastewater networks feature more than 30,000km of sewers, over 1,000 sewage pumping stations, 410 sewage treatment works, 1,561 storm overflows and more than a million manholes across its region serving 2.7 million people.

How much? £4.7 billion to 2060

The company said it anticipates the plan would impact annual wastewater bills to the tune of £166 by 2060 – currently wastewater bills are £166 for Northumbrian customers.

Action on CSOs: £80 million

Work focuses on optimising sewers through increased maintenance and lining as well as addressing causes of blockages.

Severn Trent  9.3 million customers – 92,500km of sewer pipes collect over 3.1 billion litres of wastewater per day which is then treated by 957 wastewater treatment works

How much?  £6.7 billion by 2050

Action on CSOs: £1 billion to address 361 CSOs by 2030 and more than £800 million each AMP after that to 2050.

Severn Trent has set out its ambitions to improve river health across its region in its Get River Positive commitments.

Southern has 381 sewerage catchments; 40,000 km of sewers, 366 wastewater treatment works and 3399 pumping stations in its sewage networks

How much? £7.7 billion up to 2050.

The company anticipates a bill increase of £233 by 2050 on average annual wastewater costs.

Action on CSOs: £2.9 billion of investment into reducing flooding that triggers CSOs. The company said 25% of discharges are due to surface water flooding.

The plan goes hard on preventing blockages by stopping items getting into sewers that should not be there and more proactive maintenance programmes to prevent blocks.

South West has 23,000 km of sewer pipes; 1,223 wastewater pumping stations, 653 treatment works for 1.8 million customers – plus 10 million holidaymakers

How much? £7.5 billion investment to 2050

Chief executive Susan Davy said this would impact bills, but added: “If we change how we charge for wastewater services we can make bills fairer , more affordable and progressive”

Action on CSOs: More than £3.1 billion on CSOs, which would be invested over the next 15 years to meet regulatory goals.

It has reduced discharges 27% in the past year from an average of 39 to 28 as it works towards 20 by 2025. The number of spills at beaches is significantly lower at 21 and 79% of CSOs had fewer than five spills in 2022 as the company focuses its efforts on coastal locations.

South West estimates 2-3% of the wastewater it processes leaves its networks through CSOs.

It intends to build on work done via co-funding through its Downstream Thinking programme that works with partners such as EA and councils to share the costs when a project delivers multiple benefits.

Thames has 5,123 pumping stations across its network of 100,000 km of wastewater pipes transporting 4.6 billion litres of sewage daily to 354 treatment plants.

How much? £31.9 billion to 2050

Action on CSOs: £10.9 billion, will be directed to combating the risks of harm from CSOs as part of commitments to improve rivers and streams.

Thames published its plan earlier this week that emphasises the need for sustainable drainage across London.

Wessex has 2.8 million customers served by 35,000 km of sewer pipes, with 398 treatment sites, more than 2,000 pumping stations and 1,300 CSOs across the wastewater networks.

How much? £6.6 billion to 2050 including £1.5 billion additional investment to 2030, which will add £100 to average customer bills.

Action on CSOs: £3 billion on storm overflow improvements.

One-third of that investment will be directed at improving the performance of CSOs with nature-based solutions.

The company said completely eliminating CSOs would add £300 to household charges, which the company said was currently unaffordable and would significantly negatively impact its net zero ambitions

United Utilities serves 7.3 million people and maintains 70,000 km of sewer pipes – with the highest proportion of combined networks in the country.

How much? £21.8 billion over the next 25 years.

The company warned hefty investment would be required to meet the challenges of transforming the wastewater networks.

Action on CSOs: Three-quarters of investment (£16.5 billion) will improve CSO performance to reduce dependence on these. A further £3.9 billion will be directed to wastewater treatment.

The region has the highest proportion of CSOs and subsequently has the highest number of discharges from its network.

Yorkshire has 52,000 km of sewer pipes with more than 2,000 pumping stations and 617 treatment sites handling more than one billion litres of wastewater each day.

How much? £16.8 billion by 2050

Action on CSOs: by 2030 the company will spend £800 million in the next five years.