Enhancing Water Quality from Source to Tap
Birmingham, 8 November 2018
Mike Waite, FWR Water Supply Co-ordinator
This was the 3rd WWT Drinking Water Quality annual conference. Marcus Rink (DWI) started the proceedings, outlining DWI's water quality programme. After describing the current excellent state of drinking water quality in England and Wales, despite which over 4,000,000,000 litres of bottled water are sold each year, he described the Compliance Risk Index (CRI) and the Event Risk Index (ERI) which aim to give a better informed perspective than the overall percentage zonal compliance. The CRI takes account of the number of consumers affected by any breach of standards, and the duration, along with categorisation of the significance of the parameter, while the ERI assesses the significance and actual risk to consumers from any water quality event. He spoke about the risk presented by extreme weather events, which are likely to become more frequent. The dry summer of 2018 had led to several applications (under Regulation 15) for use of new sources. He rounded off describing how Japan was future-proofing supplies with, among other things, earthquake-proof pipes and automatic shut-off of supplies, which UK companies could learn from.
Martin Padley then described United Utilities’ experiences with AMP 6 and their approach to AMP 7. Previously, the focus of the various AMPs (Asset Management Plans) had been on assets rather than systems but a more holistic approach was being embedded for AMP7, with integrated systems control from source to tap. For example, land management changes in conjunction with land managers and farmers will help to reduce contamination of Thirlmere and will minimise geosmin while all treatment works will have provision for start-up to waste and the ability for uv treatment when needed. The company’s Alternative Supply Fleet of tankers will allow supplies to be maintained in the event of large bursts. UU is heavily dependent on large trunk mains and phased replacement is planned.
In the first break-out session I attended the discussion on Protecting Public Health and Building Consumer Trust and enjoyed a presentation from Alan Brown (Northumbrian Water Group) about the regulation of consumer fittings. He stressed the need for fittings to be suitable and that the legal obligation lies with the installer. It is not illegal to sell unsuitable or non-approved fittings and few consumers are aware of the Water Fittings regulations. The Water Regulations Advisory Service (WRAS), along with the water industry and manufacturers, is working on a ‘Point of Sale’ campaign, seeking to ensure either that only regulatory compliant fittings are stocked and sold, or that non-compliant fittings are clearly labelled as such. The campaign is due to be launched in September this year.Clair Dunn then spoke about source protection and some of the challenges faced by Anglian Water, which include large rural catchments, lack of control on activities, changing land use, and sites with minimal treatment. She gave examples of the use of satellite data to identify pop-up pig farms which could impact sources, as well as the use of drones. Andrew Mayes (University of East Anglia) talked about the detection of microplastics by fluorescent tagging. A 500 ml plastic bottle can yield 109 microplastic particles but current methods of detection are slow and expensive and UEA is developing a simple, rapid and inexpensive method using tagging with Nile Red which can allow the processing of large numbers of samples. However, the method is poor with black plastics and can give false positives with chitin and some proteins and lipids. In a survey of 259 bottles of water from around Europe, 93% showed signs of microplastics with an average of 10.4 particles/litre >100 microns and 314 particles/litre <100 microns. WHO is currently assessing the health significance of microplastics.
The second breakout session was on the theme of Innovation in Action. The session I attended began with a presentation by Vanessa Speight (University of Sheffield) on managing water quality in distribution networks. After describing possible sources of contamination from works to tap, she showed that chlorine residual can decline rapidly by up to 0.2 mg/l in the first few hours after leaving the works. Chlorine can be affected by reactions with pipe walls, and by natural organics which can also form disinfection by-products (DBPs) including trihalomethanes, and serve as nutrients for bacteria. DBP concentrations can vary day-to-day. Chloramination can feed bacteria in biofilms and bacterial activity is affected by temperature.
Athena Zitrou (Scottish Water) then spoke about the use of ‘big data’ in water quality monitoring and the difficulties of combining data from diverse sources. Since before the introduction of flow cytometry in 2013, SW has increased the number of staff employed on data management and analysis and is looking at the management of bacteriological growth across a distribution system, which has necessitated the merging and analysing of seven data sets. Having identified the wide range of factors which could affect bacteriological compliance, the aim is to be able to identify where there is a risk of non-compliance.
The final plenary session of the conference addressed the role of catchment management in enhancing water quality and began with Alister Leggatt (Affinity Water) who described a case study from the Thames basin involving collaborative effort between Affinity Water, South East Water and Thames Water, all of which depend on abstractions from the River Thames and its tributaries. Using a combined programme of catchment monitoring for metaldehyde and other pesticides, they sought to identify and focus on metaldehyde hotspots and then tried various approaches to tackle metaldehyde: a metaldehyde-free scheme, risk mapping and product substitution, and payment to farmers for Ecosystem Services. New area schemes are being introduced each year such that 3,494 km2 of the c 11,000 km2 catchment are now covered by catchment schemes. By 2017, of the 13 sub-catchments, six had no samples breaching the standard for potable water quality, and in only two sub-catchments did more than 10% of samples fail that standard. As an example the River Loddon sub-catchment was found to have two areas with the highest metaldehyde levels and these were targeted. Although 14% of the farmers in the sub-catchment were not supportive, the rest were offered payment to either limit metaldehyde use or use an alternative such as ferric phosphate. As a result all samples from the sub-catchment were down to the potable water standard in 2017.
Michael Strahand (ATi) spoke about the road to Smart water networks and how they could help the industry to become more proactive rather than reactive. Smart systems are becoming more feasible with developments such as the internet cloud, ever faster data transmission speeds, and exponential growth in computing power. As network quality monitors are becoming smaller, cheaper and more reliable it is feasible to install them in hydrant and PRV chambers.
Grace Righton (National Farmers Union) considered the role farmers play in enhancing drinking water quality. She pointed out that in 1984 the UK was 78% self-sufficient in food, but this is now down to 60% and if there were to be a ban on all pesticides we would produce 40% less food. Globally, in 2020 it is expected that one hectare of planted land will feed 5.6 persons, but with population growth as it stands, by 2050 one hectare will have to feed 7.5 persons. A number of commonly used pesticides are being removed from the farmer's armoury and there is a need for suitable alternatives. Farmers have made a valuable contribution in the period from 1990 to 2017 by reducing the average weight of pesticide per hectare by 73% and of metaldehyde by 80%, while 31% less nitrogen fertiliser and 55% less phosphate fertiliser is being applied.
Phillippa Pearson (Dŵr Cymru Welsh Water) described the company's 2050 management plan. Having identified factors which might have an impact in the future, a programme of catchment management has been established and, as an example, the Brecon Beacons catchment was described. It is the source of about 40% of water supplies to Cardiff and 78% to Swansea. The Brecon Beacons is being considered as a mega-catchment and as such consideration must be given not only to water supplies but also to biodiversity, forestry, agriculture, tourism and communities. A steering group has been set up with more than 15 organisations currently being represented.
The conference ended with a presentation by Dinah Hillier (Thames Water) who spoke about catchment management and lessons from the past. Her first example was high levels of atrazine in the Bedwyn source in the early 1990s. This was finally attributed to the use of a spray train on the local railway line to control weeds. Following meetings between the spray train operator, pesticide company and Thames Water, there is now a Memorandum of Understanding between Network Rail and Thames Water to protect drinking water sources. The second example involved the detection of monuron in 2007, a herbicide not manufactured since the 1990s, in three groundwater sources used by Thames Water. After protracted and exhaustive investigations it was established that monuron could be released from epoxy resins used to protect underground electricity cables if not properly cured. Underground electricity cables were found at all three sites. Her final example was of isoproturon, a herbicide used in the autumn to treat blackgrass in winter wheat, found in the River Cherwell. In 2003 a voluntary initiative pilot brought together a group of farmers and agronomists and they suggested that farmers should be advised on when, and when not, to spray depending on weather conditions. This had limited success; however, the herbicide is now banned within the EU.
A full day, and plenty of food for thought from this 3rd annual WWT conference on Drinking Water Quality.