DWI reports CRI and ERI rises for 2018
The Drinking Water Inspectorate has revealed that the performance of England's water companies declined slightly in 2018, with Compliance Risk Index (CRI) and Event Risk Index (ERI) scores both rising.
The Drinking Water 2018 report showed compliance with the EU Drinking Water Directive across England was 99.95 per cent, a figure that has remained stable for some time.
"This figure is certainly good news and would indicate that the drinking water supply is excellent," DWI chief inspector Marcus Rink said in a letter to Environment Minister Therese Coffey. "It remains largely unchanged since 2004 but represents the high standards for compliance in England recorded since 1990."
However, there was less positive news on the CRI and ERI measures, which Ofwat is bringing in as common performance commitments for the new regulatory period.
The CRI is designed to allocate a numerical value to risk, assigning a figure to the significance of the failing parameter, the proportion of consumers potentially affected and the quality of the company’s response.
In 2018, for companies wholly or mainly in England, the CRI in 2018 was 3.86, representing a marginal increase on 2017, which was 3.62. In England, failures of samples to meet EU, national and indicator standards taken at treatment works, service reservoirs and taps all contribute to the national CRI score.
"The common link between the majority of these failures is they are due to just a handful of assets which present the majority of risk and contribute greatest to CRI," Rink said.
Companies wholly or mainly in Wales also saw an increase in CRI, hitting 4.15 from 2.63 in 2017.
"This reflects the continuing and repeated iron and manganese failures compounded by a coliform failure in June at Sluvad Works (Dŵr Cymru Welsh Water) and a bromate failure in May in Newton zone (Dee Valley Water)," Rink said. "My report highlights that consumers in Wales contact water companies about discoloured water almost three times more frequently than consumers, on average, in England and that there has been little progress in reducing numbers of contacts in recent years."
Across England and Wales, the ERI score rose to 783 from 241. While CRI indicates the risk that a water quality event will occur, ERI is used to produce a meaningful measure to quantify risk to the consuming public when there is an incident.
Rink said: "This figure was due to detections of Cryptosporidium at Knapp Mill Works (Bournemouth Water), and at works serving a large populations in London (Hampton and Coppermills operated by Thames Water) and repeated coliform detections at Testwood works (Southern Water) amongst 46 events classified as serious by the Inspectorate."
Rink noted that the decline in performance reversed a three-year trend of improvement, but added: "This does not reflect an overall increase in the number of events contributing to ERI since the total number events in 2018 was 532, well within the normal limits of event numbers since 2014.
"What it does show is the changing profile of risk by companies and where this risk is manifested within the supply system.
"Three companies were responsible for the rise in national risk in 2018. They were Southern Water, Thames Water and Bournemouth Water. The industry as a whole was not able to offset the effect on ERI for these companies, in particular the Testwood event at Southern Water. Most notable however, for a continuous year-on-year improvement over four years is United Utilities, and to a lesser extent Northumbrian Water. Portsmouth Water and Essex & Suffolk Water have both improved their performance over the last year."
For the Wales-based companies specifically, ERI improved, falling to 32 from 55 in 2017.
The report shows that, for the second year running, Wessex Water has the lowest CRI score of all nine water and sewerage companies in England.
Richard Hargrave, the company’s head of compliance, said: “We can be really proud of this result, which is down to the hard work and focus of the whole business.
“From those who collect the samples or fix the mains, colleagues in the control room who respond quickly and those who operate our treatment works or write compliance reports – there are many people involved.
“Being first is great but it’s essential that we don’t get complacent, and next we will identify any learning we can take from the report.”
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