Ensuring the quality of our drinking water is fundamental to the service we provide to our customers. We have adopted a source to tap risk management approach that identifies and proactively manages risks to drinking water quality. Termed a Drinking Water Safety Plan (DWSP), this approach is central to the way in which we ensure a continuous supply of safe drinking water now and in the future.
Understanding the risks allows us to implement effective controls that safeguard water quality, particularly during the operation and maintenance of our treatment works and network of water mains. This approach to managing risks means that we can anticipate problems and protect public health. When assessing the risks to drinking water quality we rank the likelihood and consequence of hazardous events, using a matrix to derive a numeric risk score. We repeat this process taking into account the control measures to produce an estimate of the residual risk.
To date we've completed risk assessments for all our 46,528 hectares of owned catchments, our almost 100 water treatment works, 384 service reservoirs and water towers, and 42,000 km of mains including 850 km of large diameter trunk mains. The findings were summarised in reports submitted to the Drinking Water Inspectorate in October 2008, as required by the Water Supply (Water Quality) Regulations 2000, as amended. Information obtained from the risk assessments was incorporated into our final business plan, submitted to Ofwat in April 2009. This plan will define the level of investment in maintaining and enhancing water supplies during the five year period from April 2010.
Our DWSP is key to the way in which we will manage risks to drinking water quality in the short, medium and long term. Risks are kept under continual review and the effectiveness of controls verified to make sure that the DWSP remains effective. Embracing the DWSP approach to proactive and effective risk management aligns with the views of our stakeholders and is an important part of our journey to become a world class operator of utility infrastructure.