PRIVATE WATER SUPPLIES – CASE STUDY 2013/02
The risk to water safety posed by eco-building design and the absence of effective procedures for scrutiny of the water supply aspects of planning applications
In August 2013, the Inspectorate provided on-site technical support to a local authority when carrying out a private supply risk assessment at premises owned by the local authority. The premises was a public building providing educational facilities, including water sports for schools in the area. The design was intended to be an eco-building and the private supply, which derived from a shallow well in gravel strata, provided water for all domestic purposes other than drinking (including heating, toilet flushing, hand-washing and showering). The building has a separate public supply of water for the provision of drinking water.
The risk assessment was triggered by complaints from the manager of the centre about the water being discoloured (see Figure 14) and there was staining of the sanitary wear, including the showers. When the facility was first granted planning permission and built, the new private supply was added to the local authority private supply record, however, at that time none of the parties involved (planners, engineers, council staff) understood that while the supply was not intended for drinking, it was still being used for domestic purposes and therefore needed to be wholesome as defined by the regulations.
Figure 14: Discoloured water at a handbasin
The well water is pumped into a tank and then passes to a treatment system comprising a sand filter for particle and turbidity removal, an ion-exchange unit (possibly for water softening but no design records as to purpose exist) and an ultraviolet (UV) disinfection system, all of which is powered by electricity generated on site by wind and photovoltaic cells. There was a history of interruptions to the power supply with consequential losses of the water supply and members of staff were in the habit of resetting the system whenever this occurred. This action prevented the correct cycling of the backwashing treatment programme and was therefore leading to the filters and the ion-exchange media becoming saturated and failing to adequately treat the water supply.
This case study demonstrates a common problem that arises in relation to public buildings, especially eco buildings, namely those who finance, design and commission such water systems frequently fail to make provision for onward safe operation and do not recognise or have regard for the regulatory regime for water supplied for domestic purposes. In this case, in response to an obvious design fault with the power supply, staff using the building were accessing and operating a critical part of the water system without having any knowledge or understanding of the consequences of their actions for the safety and quality of the water. Workarounds, such as resetting a system each time a fault occurs, introduce risks and hazards that go beyond causing the water treatment to fail and the water supply to be unwholesome, they potentially create risks to the health and safety of staff or users of the facility.
In premises served by both a private and a public water supply, specific risks can arise to the public water supply, therefore it is important that the water company is notified by the premises owner, as required by the Water Fittings Regulations 1999, so an inspection can be carried out to verify that the supply arrangements are satisfactory. Following the risk assessment the local authority has put in place procedures for the food safety team (who deal with private water supplies) to be notified of planning applications for new private water supplies. As regards the ecobuilding it was decided to abandon the private supply and rely solely on the mains water supply by installing two public supply storage tanks.
This audit enabled the Inspectorate to verify that the risk assessment tool provided to local authorities places appropriate weight on the management aspects of private supplies so that the risks illustrated in this case study will be identified and acted upon.
The Inspectorate recommends that local authorities put in place effective procedures for scrutinising the water supply aspects of planning applications and always notify the local water company whenever it is discovered that both a public and a private water supply serve a premises.