Private Water Supplies - Case Study 2018/04

Change of supply for long-term remediation

This case study concerns another example of a high risk private water supply at a salad growing nursery in south east England. In this instance the water was again derived from ground water sources and consumed by owners and migrant workers for domestic purposes, as well as used for watering crops. The supply was risk assessed in September 2017 and deemed to be a very high risk on account of a number of high risk hazards, all of which indicated that the supply was a potential danger to human health. Subsequent detections of E.coli and Enterococci from samples taken the following month further confirmed the risk and consumers were advised, by way of physically displaying Notices in positions on site where they were visible to consumers, to boil the water before consumption until longer-term mitigation had been put in place.

Figure 20 : Vegetation covering poorly constructed well cover

fig 20 Poorly constructed well cover

Figure 21: Supply pipework in an inadequate and unacceptable environment

fig 21

Figure 22: Header tank with overlaid polystyrene strips as a cover

fig 22

In addition to the microbiological hazards, sampling also revealed the presence of nickel and nitrate above the regulatory standard. The nitrate levels detected were 55mg/l so above the regulatory standard of 50mg/l. In November, subsequent to the previous advice to boil the water, the local authority wrote to consumers advising them of the further risk of elevated nitrate levels to infants, and highlighted that any visitors should be warned not to make babies’ feed with the water.

In December the local authority, somewhat belatedly, served a Regulation 18 Notice on the owners of the supply. However, this delay was brought about by a lack of information to enable the local authority to establish who exactly the relevant persons were. Confusingly, the Notice specified short-term restrictions of use by means of either boiling the water or not using it for drinking, cleaning teeth, food preparation (includes ice cubes and salads) cooking, preparing babies’ feeds, washing open wounds and for disinfecting feeding equipment. The risks from nitrate and nickel would not have been addressed by boiling the water.

Local authorities are advised to serve Regulation 18 (Regulation 20 in Wales) Notices as soon as practicable – for example where a potential danger to human health has been identified through the risk assessment, rather than reactively and later when a parameter has breached its respective standard. This should not preclude them from providing restrictions of use advice in the meantime, whilst the Regulation 18 Notice is being prepared. Appropriate restrictions of use should be based on health advice from Public Health England (or Public Health Wales) taking into account all breached parameters and based on the worse case. In this case advice was confusing and consumers would have been better advised not to use the water at all and to seek other alternatives, such as bottled water. The owners were advised to seek long-term mitigation through a connection to a public supply or to substantially improve the supply to the satisfaction of the local authority. The owners submitted an application for a mains connection to the local water company in February, who responded after some delays in payment, by April by stating that a connection was highly unlikely due to the distance from the nearest main. The owner was advised to approach any private pipe owners in the vicinity of the site. Unhelpfully the water company did not provide a connection estimate.

In February 2018, the local authority revisited the supply and collected samples from one of two well sources to determine the concentrations of a range of chemical parameters in the source water contained within the local aquifer. The water from this well was reportedly only being used for irrigation purposes.

The results for nickel and nitrate were again above the regulatory drinking water standard. The site owners were advised that should they wish to continue using the supply, appropriate and extensive treatment would be necessary to mitigate the existing chemical risks.

In March, in view of the approaching deadline for the completion of remedial work specified in the Notice, the local authority was informed, by the site owner, that they were still waiting to hear from the water company with regard to their application to connect to the public supply. As the deadline for the connection drew nearer it became increasingly apparent to the owner that the water company would not meet the deadline set by the local authority to mitigate the risk, due to delays caused by the water company, and hence were beyond his control. In response to this the owner asked the local authority if the completion date could be extended to the end of June, which was granted. The connection to the public supply met the revised deadline.

This case study illustrates that where co-operation exists between relevant persons and the local authority, remediation can be achieved in a reasonably timely manner. In this instance the necessary work was held up, although it was through no fault of the owner and the local authority were content to extend the completion deadline to accommodate the delays caused by the third party. However in practice the timely resolution in this instance was largely due to the presence of a ready solution (i.e. connecting to a private main nearby), enabling the owners to put in place a relatively affordable, long term, sustainable solution.

Local authorities are reminded that Regulation 18 (20 in Wales) Notices must be served as soon as a potential danger to human health is identified by the risk assessment. Confirmation, by way of sampling, only causes further delay in protecting consumers, and the information it provides is limited by the number of parameters analysed for. Furthermore, where regulatory standards are met through sampling, it does not necessarily evidence that a supply is safe at all times, or negate the need to serve a Notice based on potential risk. In this case the local authority did, however, seek to immediately protect consumers by the provision of restriction of use by boiling the water, but this did not take into account potential risks of chemical contamination, such as nickel, that were later confirmed by sampling. Appropriate restriction of use should be guided by advice from health professionals.