Project

This project will address key issues in order to meet the outcome “Ownership and responsibility for water quality is clear and all part their part in its protection”. The project will improve our understanding of the complex chemistry which underlies the control of lead solubility.  Recent developments in analytical instrumentation open up a number of avenues to enhance the industry's understanding of the surface chemistry which facilitates compliance or causes failure.

The drinking water and environmental regulators have stated that they see the main effort to improve water quality / quantity to be based at a catchment level. This will aid the minimisation of algae, pesticides and colour in the raw water sources which in turn will minimise issues water companies face from taste & odour contacts.

The previous UKWIR project, “Quantifying the benefits of Catchment Management” was undertaken over 5 years ago and the project “Catchment Management – how do we know its worked” was started in 2015/16 but put on hold indefinitely. Catchment management has gained traction since then with some companies making great progress. The time is right for a review of the evidence, for or against, catchment management.

The development of phytoplankton in water supply reservoirs across the UK can cause severe treatment problems at water treatment works, resulting in a loss of output, increased treatment cost and, in extreme cases, threatening the continuity/resilience of water supply. Events of this nature are, however, relatively infrequent and may not occur for many years. This makes it difficult to plan for them and/or to maintain continuity in the measures required to reduce their risk and react to problems when they occur. In addition, continuity in monitoring and maintenance of records to assess the risk of these events is difficult to maintain.

As a result, water companies may be unprepared for extreme phytoplankton blooms and therefore not deal with them in the most efficient and effective way. This situation is unsatisfactory because there is an ongoing risk to continuity of water supply to customers, the primary legal obligation of water companies. Furthermore, the risk of these extreme events is likely to increase as there is a growing  body of evidence that suggests that algal blooms are occurring at times of the year when they have never or rarely been seen before and they are lasting longer, a possible result of climate change. If our changing climate is a driver for what we are seeing we need to establish clarity about the mechanisms involved in driving the change, so that we might understand just how bad a problem it might become.

 The Water Industry needs to ensure that the knowledge base to understand the risk of severe phytoplankton events affecting water treatment is improved.  It also needs to develop better planning proocedures to reduce the risk of these events and to manage them better when they occur. 

 

There is significant interest in the prevalence of nano-particles and microplastics entering the environment.

There is a lack of understanding for the water industry with regards to the occurrence, fate and behaviour of these particles during transport and Waste Water Treatment; once dischrged to the river system there is limited understanding of how these particles behave; if river water is abstracted down-stream there is a lack of knowledge around the occurrenceand degree of removal of these particles through water treatment processes.

Current WQ Indices produced by DWI and now used by OFWAT do not represent consistently the level of risk to public health or degree of customer impact.
The statistics underlying the indices are flawed and need to be revisited to fit the current needs of the Industry, its customers, and its regulators.

There is an increasing trend for water testing laboratories, and water supply companies, to send all microscope slides on which Cryptosporidium oocysts have been seen to the Cryptosporidium Reference Unit, Swansea, for genotyping (identification of species). An internal audit of results at the CRU has shown that there is a positive relationship between typeability and the number of oocysts seen on the slides. However, most slides received had just one oocyst, and these are only very rarely typeable to the required level by current methods. This is largely due to the small amount of Cryptosporidium DNA present.

The methodology employed currently for Cryptosporidium slide genotyping uses optimised, validated methods for removal of Cryptosporidium oocysts from slides and optimised DNA extraction and purification from low numbers of oocysts; these were developed and validated as part of WRF project 4099. The PCRs developed and validated at the CRU for the UK water industry have been shown to be sensitive and specific for the detection and differentiation of all Cryptosporidium species and specifically C. parvum and C. hominis. For slides containing greater numbers of oocysts, the current strategy for unravelling mixed populations of Cryptosporidium spp. on a slide – by means of multiple PCRs each using small volumes of DNA samples - is successful, with a high rate of typeability and more than one species frequently detected. However, more recently there has been a trend for more slides with small numbers of oocysts to be submitted, and where there is a low amount of target DNA in the sample (from <5 oocysts), the strategy is less successful and a single, large volume assay may be more appropriate. The challenge is to design an assay that provides the required level of typing, and to introduce as much target DNA as possible in to the PCR mix without compromising the chemistry of the assay.

Due to the high demand the increased submission of slides with small numbers of oocysts places on laboratory resources, generating little in return by way of genotyping results, and following consultation with stakeholders, the CRU intends to temporarily withdraw the slide genotyping service for slides with <5 oocysts seen where these are not part of an outbreak or public health investigation of a water quality incident. This will allow staff to undertake the research and development work described below to improve typeability and sensitivity, while retaining specificity, for the future. This approach has been discussed with DWI and the Industry and accepted as a proportionate approach, facilitating the delivery of an improved methodology and service for the future.

UKWIR has undertaken an ambitious programme to define longer term, strategic research needs in key areas via its Big Questions initiative.  Drinking water quality (DWQ) is the third such area to be developed.  

Drinking water quality is of key importance to public health and provision of safe drinking water has been recognised as one of the greatest technological advances of the last century.  The future challenges in DWQ include: raw water quality deterioration due to climate change and related factors, increasing expectations of quality from both the public and the regulators, energy efficiency in treatment, and delivering quality with aging infrastructure. This review will consider all options for improving DWQ from catchment to tap and identify the most appropriate interventions.

A research programme for DWQ must consider improvements to existing drinking water infrastructure to maintain water quality in the face of source water degradation and limited resources - particularly in the short term – but then identify the potential possible shifts in the current drinking water infrastructure paradigm that might include partially- or fully-decentralised treatment, delivery of different grades of water quality, new materials, and innovative treatment processes in the longer term.

Despite several years of activity 2014 still saw significant numbers of sample exceedences for metaldehyde. 2014 also saw the removal from sale of methiocarb based slug pellets, reducing to two the actives ingredients available for slug control. There is the potential for an increase in the number of exceedences in treated drinking water as a result.  Consequently, there is a need to identify routes to improve the rain-fastness of slug pelletts; to identify potential improvements to palatability to reduce the number of pelletts needed for effective control and to identify potential replacement active ingredients which offer lower risks to water supplies.

Both Ofwat and the Environment Agency (EA) have said recently that they have some concerns with the current Sustainable Economic Level of Leakage (SELL) process for the setting of leakage targets.  The recent EA guidance on leakage for Water Resource Management Planning (WRMP19) says :

“There is increased realisation that SELL may not be the most effective way to plan leakage levels.  WRMP19 will be the final time that a leakage figure is derived from SELL.  We expect water companies to evolve and move away from SELL for WRMP24 and to innovate to reduce leakage beyond the current levels”.

 The Ofwat consultation document on outcomes for PR19 (February 2017) expresses a different view :

“Companies should report their SELL in business plans, explain their assumptions on future improvements in leakage reduction efficiency in the SELL, and explain how its Performance Commitment for leakage is appropriate in relation to SELL”. 

 There is a strong feeling amongst companies that leakage targets should continue to be based on a sound economic analysis.  However, the cost of leakage management relationship for SELL modelling is derived from analysis of the company’s own historical leakage management performance data.  It is therefore a valid criticism of this process that if a company has been historically inefficient, then this inefficiency becomes built into the SELL.

In the UK, there is approximately 50,000km of Asbestos Cement (AC) water mains, 60% of which have been in service for over 50 years, the majority (approximately 66%) being small diameter, 100mm or less. With time, it has been noted that the failure rate of AC mains is increasing, demanding the need of replacement which can cost around £5 billion.

Several studies have identified that the principal failure mechanism of AC water mains is:
- exposure to conveyed water that has an aggressive nature, typically low alkalinity
- exposure to aggressive soils, typically low pH
- failure of the joints, typically due to microbial attack on the natural rubber joint rings

All of the above deterioration mechanisms are directly proportional to time, i.e., the longer the exposure, the greater the level of deterioration. Whilst there may be opportunities to extend the life of such pipes through lining and pressure management, these interventions are unlikely to be a success due to the small diameter and long-term exposure to the aggressive conditions that has already taken place.

If the level of AC main failures (pipe and joints) continue to increase, this will impact on the number of interruptions to supply and levels of leakage.

This project will be a collaborative project with the Water Services Association of Australia (WSAA).

It is estimated that about 25% of the leakage within a water distribution network is located on a customer's property and occurs within the pipe that is not the responsibility of the Water Companies. However, this is still included in the leakage figures that water companies report to regulators.

The customers can be divided into household and non- household. For household customers, water companies offer a range of solutions from providing free advice to free repairs. There is limited understanding of how these different policies ultimately impact on reported leakage levels and overall cost to the business. For non household customers, water companies don't provide free repair services as a part of their standard customer leakage policy. However, with the opening of retail market, communication with non-household customers has become difficult, slowing down the leak repair and increasing the level of leakage.

Water Companies are also increasingly installing smart metering which identify leaks with very low flowrates. This has challenged the industry to find such small leaks, which are not cost effective to repair, and can be difficult to locate.

The cleaning of water mains has traditionally been a method of removing any deposits that have built up over time and can cause water to become discoloured. The benefits of mains cleaning can be varied and dependant on a number of factors, such as mains condition, system hydraulics, water chemistry, upstream influences (eg. service reservoirs, pumping stations, trunk mains), aggressiveness of the cleaning intervention, the customer management approach, the sampling frequency post cleaning etc.

There are a number of traditional and innovative techniques available to clean water mains. This project would look to assess the benefits of each of the cleaning techniques taking into consideration each of these factors.

Of particular interest would be the cleaning of unlined iron mains since there is a belief that cleaning of such mains causes more problems than it solves. Generally, the industry, has chosen to extend the life of these mains by relining, using various types of internal linings resulting in a % of unlined cast iron mains that is likely to be around 30% - 40% nationally. The unit cost to replace or reline such pipes will mean it will take many years at current rehabilitation rates before the issue of unlined cast iron mains is addressed, consequently there is a keen interest in assessing the efficacy of cleaning.

Optimisation of mains cleaning may result in the potential to defer OPEX.  Increased technical knowledge across the Water Industry will allow Water Companies to adjust strategies, etc, based on informed decisions.  This will also have an impact on discolouration as well as taste and odour. 

The Water Industry has very little knowledge of the impact of reducing leakage levels on the numbers of repairs that need to be carried out each year, nor on the relative proportions of visible and invisible leaks.

Introduction of performance commitments and changes in SIM, with associated rewards and penalties, has increased focus on the customer service aspects of burst and leak repairs, whether it is unwanted contacts, interruptions to supply or associated discolouration contacts. Customer Service impact mitigation costs will add to the operational costs for repair and consequential damage.

Historic leakage strategy has focused on Sustainable Economic Level of Leakage (SELL). Leakage strategy now must consider the customer acceptability aspects of leakage. Most customer views are based on the impacts of visible or reported leaks and the impact of repairs on customer service.

Single company data is insufficient to discern any impact due to leakage level as it is masked by weather and relatively static targets. Pooled company data, combined with planned AMP6 reductions should provide a data set to understand any increases in repair frequency, changes in proportions of visible leaks and the time period for change.

Service reservoirs and water towers constitute a major asset base in the water industry. Managing these assets effectively ensures operational efficiency and water quality confidence. To manage these assets now and in the future, it is vital that water companies understand best operational practises as well as potential future strategies to allow better risk management and minimise whole life cost.

There are few industry wide asset management and decision support tools available which encompass the asset lifecycle as a whole, from planning and construction, through operation and maintenance to renewal/replacement and decommissioning. This research will identify and share best practise for the asset lifecycle of service reservoirs and water towers and their component parts.

Critical to the project will be the use of the “Framework for Expenditure Decision Making”[1] (FEDM) approach developed by UKWIR in 2014/15.

 

[1]14/RG/05/40: Common Framework 2014: Framework for Expenditure Decision Making: Part 1 Scope Definition

Distribution Maintenance staff at water companies know well that many leaks and bursts, once excavated, prove to be at the location of a previous repair, and occur as a result of a failure of the old repair. However it is not known how much data is collected on this, and there is no quantitative evidence of the magnitude or significance of this problem at national level. Nor has there been any study of the reasons for the failures, i.e. whether they are due to deterioration of the clamp or other repair materials over time, or whether they are caused by faulty workmanship at the time of the initial repair.

Many companies do record the types of failure within their records of mains and service bursts. However these descriptions are often very brief (e.g. “pin-hole”), and the fact that the failure was at a previous repair may not be recorded. This project will initially assess the availability of suitable data, in collaboration with participating water companies. The UKWIR National Mains Failure Database may also be a valuable source of data.

Modern technology has made it possible to collect much greater quantities of data, and at higher resolution. Leakage analysis methods and leak detection technology have both made many advances in recent years, but data collection and manipulation processes have hardly changed. The basic principle of measuring minimum night flow into a DMA, and then subtracting estimates of household and non-household night use to give leakage, remains unchanged in the past 30 years.

However the recent growth in smart networks, and particularly the use of smart meters for revenue purposes, could offer many new opportunities for better leakage management. It is essential that these opportunities and benefits are identified now, so that water companies can take them into account when making their choices of which smart technologies to invest in.

Three of the key parameters in the analysis of leakage data are:
- Average zonal pressure (AZP)
- Average zonal night pressure (AZNP)
- Hour-day factor (HDF)

In 2012, Strategic Management Consultants (SMC) published a report on €œA Review of SELL and its Integration with WRMP€, commissioned jointly by Ofwat, DEFRA and the Environment Agency. Among the recommendations of this report was the following:
There is a need to review the methodologies for assessing average zonal pressure (AZP), average zone night pressure (AZNP) and hour to day factors (HDF) as part of the WRMP process. An industry standard methodology is needed, which should take account of the need to change hour to day factors with different forms of pressure management.€

In other words, hour to day factors should reflect current pressure regimes.

A specific problem has been identified with the current method of calculating HDF. In some cases, when HDF has been recalculated following implementation of a pressure reduction scheme, the calculated leakage has risen rather than fallen.

Collate and analyse household consumption data from throughout UK & Ireland to provide an overall understanding of consumption, night use, plumbing losses, and supply pipe leakage. Develop options for UK & Ireland longitudinal consumption monitor to provide a temporal understanding of demand.