Rainscape Llanelli

We have invested £115 million across Llanelli and Gowerton in our innovative RainScape work between 2012 and 2020.

RainScape is Welsh Water’s approach to managing surface water and reducing sewer flooding by separating rain water from the existing system, slowing down the rate it enters the network and by redirecting it to local rivers and watercourses, and in some cases, removing it completely. It helps reduce sewer flooding and pollution and creates greener, cleaner communities for us to live in.

Our RainScape work was particularly needed in Llanelli as the area sees almost as much storm water in its network as Swansea, despite the fact that Swansea serves three times the number of properties, and three times the area compared with Llanelli.

With the help of contractor partners, Morgan Sindall, we have completed 36 RainScape projects in the Llanelli area since the project was launched in 2012. This has involved laying around 14 miles of new pipework and kerb drainage, tunnelling just under one mile underground to create rainwater sewers and planting almost 10,000 plants and trees in swales, planters and basins.

How does RainScape work?

We’ve looked around the world - from Malmö, Sweden to Portland, USA - to help us develop a new way of doing things. RainScape catches rainwater and slows down the speed at which it goes into our sewer network.

Basins and Planters

Shallow basins, often filled with plants, catch and clean the water that runs from roofs and road before soaking into the ground or slowly making its way into our sewers.


Long, shallow channels, often filled with plants and trees, catches, slows down and cleans rainwater before soaking into the ground or slowly making its way into our sewers.

Porous paving

Paving with lots of tiny holes which allow water to pass through and soak into the ground, rather than running straight into our sewers.

Grass channels

Long strips of grass that can be put on streets to help absorb rainwater.

Underground storage

Underground storage boxes which catch water during heavy rainfall before either soaking into the ground or slowly running it into our sewers.

Station Road, Llanelli

Between 2017 and 2020, we worked on our biggest RainScape project in Llanelli, which saw a £20 million invested in a three-phase project. The work was carried out in and around Station Road, Emma Street and Ann Street, and the largest part of the project was the creation of a new surface water tunnel from Llanelli town centre to Delta Lakes to take rainwater away from our sewer network in Llanelli.

The tunnelling machine for the project was named ‘Jarvis’ by Morgan Smith, who was a pupil at Bigyn Primary School.

Parkview Terrace, Llanelli

In 2017 we invested £4.3 million on a RainScape project in and around Parkview Terrace. The project saw the creation of our biggest swale on the grassed area opposite Parkview Terrace, which is designed to attenuate 200m3 of rain water.

As part of this work we installed new manholes, pipework and kerb drainage in a number of streets near to the swale including New Zealand Street, Greenway Street and Raby Street.

As part of this work we installed new manholes, pipework and kerb drainage in a number of streets near to the swale including New Zealand Street, Greenway Street and Raby Street.

Our work was completed in July 2017, and the swale was officially opened by Llanelli MP Nia Griffith in August 2017.

Queen Mary’s Walk, Llanelli

In September 2013, we completed a RainScape project to construct a swale on the Queen Mary’s Walk playing field.

The 100-metre-long swale was designed to capture rainwater and let it gradually filter into the below ground storage unit before slowly being released into the sewer network. The swale was planted with a range of plants and trees especially selected to help with soaking up the rainwater.

The project cost £850,000. It is anticipated that it will remove approximately 4,365,000,000 litres of water a year from the sewer network. That is equivalent to almost 9 million bottles of drinking water.

Stebonheath Primary School, Llanelli

We invested £500,000 in a surface water removal scheme at Stebonheath Primary School, which was constructed during the summer holidays in 2013.

This investment transformed the primary school’s playground by adding a pond, a swale, planters, permeable paving, water butts and an outdoor educational area.

The school children were heavily involved in the design of the scheme and participated in a workshop with the engineers where they input into how the playground should look.

This scheme helps to remove 4,600m3 a year from the sewer network – that is equivalent to 11.1 million bottles of drinking water.

RainScape and water efficiency messages have been embedded into the school curriculum ever since.

Glevering Street / Swansea Road

£2 million was invested in a RainScape project in and around Glevering Street and Swansea Road in Llanelli.

The project, which was completed in May 2014, saw new drainage kerbs, grass channels and planters installed.

This project is helping to remove 22,558m3 a year from the sewer network, whilst also improving the environmental and aesthetic value of the area.