Dalkeith (Rosebery Supply Zone) - Water Main Repair Incident

Scottish Water (SW) took a sample of water from a property in Dalkeith, near Edinburgh on 10 April 2009. The sample was taken following a request from a customer who had contacted SW about discoloured water. The results of the analysis carried out on the sample showed that the water contained high levels of iron and manganese. The property was tested again on 17 April 2009 and this also failed to meet the required standards, this time with high levels of aluminium as well as iron and manganese. It was not until 30 April that a further re-sample confirmed the water was clear and compliant with the Regulations.

A water main burst in the area on 7 April, which required SW to supplement the supply from an adjacent area. To allow this to happen , SW had to operate a boundary valve which under normal circumstances is closed. When boundary valves are opened the water tends to flow in the opposite direction to which it normally does, so there is a great risk of any deposits that have built up in the pipes over the years being dislodged, causing dirty or discoloured water to be supplied to customers. SW has procedures in place to guard against this happening and provided these procedures are followed, any such risks should be minimised. DWQR considered that SW may not have fully complied with their procedures in this instance so a full report on the incident was requested from SW.

Having considered the incident report, DWQR can find no evidence of any non-compliance with the procedures. An impact assessment was carried out before work on repairing the burst water main started, this included the operation of the boundary valve and obtaining the appropriate authorisation. Training records for the operator involved also show that he had undertaken the necessary training. Furthermore, the team that carried out the repair were appropriately trained and had been successfully audited internally in the previous 6 months. The repair was disinfected and the main was flushed with a SW operative in attendance.

The delay in the resample was apparently due to it not being flagged as requiring special priority. To address this SW is introducing guidance on sampling to ensure that incident samples are dealt with as quickly as possible. A copy of the incident report was also to be circulated to all of SW's regional managers to raise awareness of the incident and to learn from it.

DWQR has concluded that although there is no doubt the customer received discoloured water, SW acted correctly in the circumstances. This property does appear to have been the only property to have suffered at the time in that area of Dalkeith . It is unfortunate however that the customer was inconvenienced in this way but this incident serves to emphasise the importance of having appropriate procedures in place and the need to comply with them to safeguard customers and minimise any risk to public health