With mains renewal at 0.4% per annum, is pipe lining the solution?

It is no longer the case that our water networks are ‘out of sight, out of mind’. High leakage rates drive repeated media criticism, and the public are better informed now than ever on ageing assets and investment needs.

The importance of our water distribution networks is not lost on the National Infrastructure Commission (NIC), who have recently told Ofwat that underground asset replacement rates (currently 0.4% water mains renewal per annum) need to be significantly higher, and a more consistent and forward-looking approach to measuring asset health should be developed. It is difficult to argue against the logic, but with the cost to bring water and sewerage systems up to date quoted at £56bn and the current policy to keep customer bills down, it remains a near-impossible balancing act. However, we know full asset replacement is not the only tool the water companies have.

The use of pipeline rehabilitation techniques to extend the life of the existing pipeline asset is not new; cured in place and spray lining techniques have been used by the water industry globally for many decades. Cured In Place Pipe (CIPP) being the go-to technology for sewer rehabilitation, initially in gravity systems only, but more recently in pressurised pumped sewers and most recently through WRc’s support for use in gas mains in the UK. Spray lining has also seen an evolution of the resins and technology with a long history of use in water mains. Peak use was in the late 1980s and early 1990s in the UK but after a long period with very little UK activity we are seeing a rival of the technique.

So where does lining fit into the industry’s current challenges?

If we first look at CIPP, there is a clear potential as a cost competitive, low carbon rehabilitation technique for water mains. It is already used in other countries around the world with new product formulations delivering improved installation, cure and structural properties, which are better aligned to the challenges of pressure variations including transients and negative pressures. Perhaps the biggest challenge to a competitive drinking water CIPP market in the UK is achieving the specific approvals (DWI Regulation 31).

The revival of spray lining of water mains is demonstrated by the Water UK’s Expert Resin Lining Group (ERLG) now in its second year after reforming. At the same time contractors are going through the process of approval under the WIS 4-02-01 which is currently being brought up to date by the ELRG.

We will, without doubt, see an increase in the use of spray lining techniques during the next AMP.

A lot about lining is not new but there is some activity which highlights the industry’s drive to move forward and make lining fit for the 21^st century. The Ofwat Innovation Competition (OIC) Designer Liner project, led by Yorkshire Water, aims to develop the next generation of innovative lining technology with a guaranteed longer life, and the potential inclusion of novel aspects such as self-repair and bio-suppressants. However, fundamentally for installation, all lining techniques need access into the water main. Digging down and cutting into the pipe is highly disruptive and doesn’t align with the industry drive to keep customer disruption to the minimum. This is where another OIC project, Universal Access Point for Water, led by Sutton and East Surrey Water, fits in. This project will develop innovative access solutions opening the network to enable both in pipe surveys and repair and rehab techniques. Closely aligned with both these projects is the National Leakage Research and Test Centre (NLRTC), another OIC piece of the jigsaw which will provide the facilities to test new technologies in a realistic safe environment in parallel to gaining Reg 31 approval.

The challenges and the scrutiny may have never been greater but the wide range of existing and new pipe lining solutions being developed offers plenty of hope and opportunity for increasing the asset life of our water mains. All this, 42 years after CIPP was first invented.