Making the implicit,explicit: time for renegotiating the urban water supply hydrosocial contract?

Today's modern cities' ‘big-pipes in, big-pipes out’ potable water supply approach does not offer society the resilience for adaptation to future climate challenges. One approach towards building resilience would involve cities adopting diverse, alternative water supplies; such as recycled wastewater, greywater and stormwater, within a fit-for-purpose philosophy, incorporating a mix of centralised and decentralised technologies. Globally, modern cities have limited on-ground experience with such complex approaches, despite ad-hoc policy rhetoric to the contrary and multiple technological options. Through considering the implicit and technocratic hydrosocial contract underpinning the current ‘big pipes’ approach, it appears the judgement and advice of ‘water experts’ is a significant determinant regarding opportunities for realising more resilient water supplies. Contrasting primary and secondary survey data from water experts and communities across Australian cities in relation to their receptivity to alternative water supplies; it is evident that community members are far more receptive than water experts expect. Thus, this difference in perception is potentially a significant barrier to realising a resilient approach. Path-dependant decision-making and practice is pervasive throughout the urban water field, and while the physical artefact of the traditional water supply system remains largely invisible and disconnected from communities, it is the implicit hydrosocial contract that keeps water experts disconnected from communities. Based on evidence presented in this paper, shifting the current hydrosocial contract to a more resilient approach is vulnerable to business as usual. Recommendations are offered for fundamentally reshaping this contract through deliberative processes that work towards enabling co-governance, co-design and co-management of this alternative and complex water supply approach into the future.     

Pollution source control by water utilities – characterisation and implications for water management: research results from England and Wales

The treatment of agriculturally polluted water to potable standards is costly for water companies. Changes in agricultural practice can reduce these costs while also meeting the objectives of European Union (EU) environmental legislation. In this paper, the uptake of source control interventions (SCIs) by water and sewage companies in England and Wales as a means of controlling agricultural pollution is investigated. Data were gathered using semistructured interviews with water and sewage company representatives. Interview data were processed using thematic and content analysis. Results showed that SCIs are increasingly being adopted in England and Wales. Of the four types of SCI identified, the so‐called ‘Liaison’ type dominated. This type of intervention requires intermediary organisations with local expertise in water catchments. Differences in pollution source control between EU countries, and England and Wales are examined. Evidence indicated that ‘Liaison’ SCI s types may be more prevalent in countries where water supplies are privatised.     

Microbial quality of rainwater supplies in developed countries: a review

The current paper examines the reported microbial quality of rainwater supplies. The majority of microbial contamination derives from debris and faecal material deposited on the roof surface, principally from birds. The prevalence and level of contamination varies widely, both in terms of indicator organisms and pathogens. Gastrointestinal pathogens such as Campylobacter spp., Salmonella spp., Cryptosporidium spp. and Giardia spp. have all been isolated from harvested supplies, although these may not always be of types infective to humans. In the UK, there are currently no regulations in respect to the microbial quality of harvested rainwater for non potable use, although there are generally standards relating to the required plumbing to ensure that potable and non potable supplies remain separate.     

The concept of choosing a list of indices and their regulatory values for determination of hygienic requirements and control over the drinking water quality in Ukraine

The paper presents new conceptual approaches to establishing indices for the quality of physiologically wholesome drinking water for the population based on the analysis of the composition of surface and underground sources of water supply in Ukraine. We have proposed ecological regulations for the quality of Ukraine’s surface waters as a basis for the choice of quality values of these indices. These regulations provide effectively for the absence of anthropogenic contamination of natural sources of water supply. We have also considered present-day approaches to regulating maximum admissible concentrations (MAC) of drinking water impurities during its conditioning at the stations of centralized water supply. We have provided qualitative MAC values of water impurities, which may be recommended taking into account technological and economic possibilities.     

Quantitative microbial risk assessment with respect to Campylobacter spp. in toilets flushed with harvested rainwater

In light of increasing pressures on water supplies in some areas, water demand management and water conservation techniques are likely to become increasingly prevalent. In‐house systems using alternatives to mains supplies for nonpotable uses present one such option for reducing potable water demand. This paper, through a formal desk‐based health impact assessment (HIA) and quantitative microbial risk assessment (QMRA), examines one of the possible health implications (Campylobacter infection from toilet flushing) resulting from the use of rainwater harvesting in the home in the United Kingdom. This is investigated using data from the literature and a hypothetical case study population of over 4000 people (based on data for the ‘average’ population in England), with the results being expressed as disability‐adjusted life years (DALYs) (on an annual basis) and placed in context of the ‘tolerable’ risk from drinking‐water supplies.     

Comparison of engineering costs of raw freshwater, reclaimed water and seawater for toilet flushing in Hong Kong

Hong Kong is one of the very few coastal cities in the world that use ‘dual water supply systems’. Dual water supply involves two distribution systems: a freshwater system for potable use and a seawater system for toilet flushing. This study looks into the feasibility, from an engineering cost point of view, of extending seawater supply into districts where potable water is still being used for toilet flushing, including South District of Hong Kong Island, Sai Kung, Northern New Territories and Northwest New Territories. Besides seawater, raw (untreated) freshwater and reclaimed water (treated effluent from local sewage treatment works) are also considered to be used for toilet flushing for these districts. Six cases are developed for comparison by using the lowest net present value of cost criterion. The result shows that using seawater for toilet flushing in these districts has the best engineering economy.     

A rapid method for the defluoridation of fluoride‐rich drinking waters at village level

Many water supply schemes, particularly in developing countries where dug wells form the major water source, contain excess fluorides normally detrimental to dental health. A simple and inexpensive method of defluoridating these fluoride‐rich waters was required and it was found that kaolinitic clay forms a suitable raw material in the defluoridation process. Fluoride adsorption and desorption reactions in clay were investigated. At equal concentrations of total fluoride in solution, fluoride retention was greatest at pH = 5.6 and decreased both at low and high pH. Fluoride sorption conformed to both Langmuir and Freundlich isotherms over the entire range of fluoride concentrations (5–25 ppm). However, fluoride desorption conformed only to the Freundlich isotherm. These properties make it possible for the use of kaolinitic clay as defluoridating material to be used in potable water supplies at village levels.     

Water and Disease After Croydon: A Review of Water-borne and Water-associated Disease in the UK 1937–86

T here W ere 34 outbreaks of water-borne disease recorded in the UK between 1937 and 1986, comprising over 11794 cases and at least six deaths. A total of 21 outbreaks were due to public water supplies, 11 of them contaminated at source; in eight of these 11 the water was unchlorinated or defectively chlorinated. None of the six reported deaths was due to contamination of public supplies at source. About 1000 cases of gastro-intestinal illness were caused by consumption ofafoods, particularly milk and canned nicats, that had been contaminated by polluted water during processing. Shellfish harvested from pollutcd cstuarics gave rise to increasing numbers of outbreaks of viral gastroenteritis and hepatitis A. The recreational use of water was associated with about 400 serious infections and probably many minor illnesses. Sonie hospital infections may have hecn derived from the potable water supply. A total of 14 outbreaks of legionnaires' disease and eight of humidifier fever were associated with water in buildings.
The future control of water-borne and waterassociated disease demands not only continued vigilance in the water industry but closer collaboration between public health doctors and water engineers and scientists.     

The Management of Potable Water Treatment Sludge: Present Situation in the UK

This paper details the results of a survey of UK potable water supply organisations, which was undertaken in 1998 on behalf of UK Water Industry Research. An extrapolation of the data indicated that, in 1997, about 131 000 tDS of water-treatment works sludge were produced in the UK. The relevant methods and associated costs are reported. A number of companies are using, or developing, novel waste-management methods for water-treatment works sludges, such as incorporation into bricks and spreading on agricultural land, and these are discussed.     

The Evolution of Water Resource Development in Northern Ireland

There is no shortage of a basic water resource in Northern Ireland because average rainfall across the province varies from 900 mm to 1100 mm per annum, east to west. However, as elsewhere, there is a constant need to ensure the provision of adequate water sourceworks.
In 1973, the Water Executive of the Department of the Environment for Northern Ireland took over responsibility for the water and sewerage services which were previously controlled by 76 local and district authorities. In some cases, source schemes which had been inherited reflected the parochial nature of the promoters rather than the wider regional approach. Upland impoundments were traditionally favoured and still account for 40% of all sources. Freshwater loughs were also used and Lough Neagh (the largest freshwater lough in the UK) accounts for 27% of all public supplies, with other loughs contributing a further 9%. River intakes at 13% and groundwater and springs at 11% make up the remaining sources.
This paper outlines how water resource developments have evolved in Northern Ireland and describes the approach and recommendations of the study.     

Service mains through the basements

The practical nature of much research work in some countries is illustrated by this report from the Civil Engineering Institute of the Bauakademie of the German Democratic Republic. It describes how the crucial installation of mains supplies in urban rehabilitation ‐ for district heating, water supply, electricity, telephones ‐ is achieved by forming a continuous ‘tunnel’ through the basements or cellars of old terraced buildings, and running the new supply networks in specially constructed service ducts, thus avoiding costly and complex road works.     

Up‐flow Clarifier for emergency water treatment

The supply of adequate amounts of safe water for drinking and hygiene during natural disasters or armed conflict can be compromised and is one of the priorities in public health interventions to prevent the spread of disease. When surface waters are the only viable source, emergency water treatment kits are usually deployed by relief agencies for the supply of water. One option is the Oxfam Field Up‐flow ‘Clarifier’ Kit, which was designed to treat raw waters with high turbidities to adequate levels [i.e. <5 nephelometric turbidity units (NTU)] and at a relatively high yield (i.e. 10 m³/h). Performance data on the Clarifier from its development and during pilot and field evaluations are presented, as well as its long‐term use records during the emergency response to the Indian Ocean tsunami. This modular treatment system has been shown to be robust in being able to produce drinking water of turbidity levels considered to be acceptable during emergencies over a prolonged period.     

Transition to a water-cycle city: risk perceptions and receptivity of Australian urban water practitioners

Transition to a water-cycle city, a sustainable urban water management future, requires the implementation of centralised and decentralised systems to augment potable water supply, protect waterways and enhance urban liveability. Risk is simultaneously driving and impeding this transition. However, risk perceptions of water practitioners and how they affect practitioner receptivity to future modes of urban water supply are poorly understood. This study characterises risk perceptions and attitudes of Australian urban water practitioners towards alternative water systems and uses a receptivity framework to suggest how receptive practitioners are to these systems. Differences between cities are identified, suggesting how familiarity might influence receptivity. These results can inform strategies to enhance receptivity, including improved communication within the water industry and beyond with its various stakeholders, improved cost-projection frameworks to provide a quantitative metric of the benefits of sustainable water options, and a shift from ‘learning to manage’ to ‘managing to learn’.     

Contamination of potable roof-collected rainwater in Auckland, New Zealand

One-hundred and twenty-five domestic roof-collected rainwater supplies in four rural Auckland districts were investigated in a cross-sectional survey to determine water quality. Samples of cold faucet water were analysed for physico-chemical and microbiological determinands, including metals (zinc, copper and lead), bacterial indicator organisms--heterotrophic plate count (HPC), total coilforms (TC), faecal coliforms (FC), enterococci (ENT), bacterial pathogens including Salmonella spp., Legionella spp., Campylobacter spp., Aeromonas spp. and the protozoa, Cryptosporidium and Giardia. Twenty-two supplies (17.6%) exceeded one or more of the maximum acceptable values (MAV) or maximum guideline values for chemical determinands of the New Zealand Drinking Water Standards (NZDWS) and 70 (56.0%) supplies exceeded the microbiological criteria of < 1 FC/100 mL. Eighteen supplies (14.4%) exceeded the NZDWS MAV for lead of 0.01 mg/L and three (2.4%) exceeded that for copper, of 2 mg/L. Those supplies with lead or galvanised iron comprising part of the roof or collecting system were more likely to show lead contamination (p = 0.019) as were those supplies with a pH less than 7 (p = 0.013). The presence of the indicator organisms HPC, TC, FC and ENT were all significantly correlated with one another. Aeromonas spp. were identified in 20 (16.0%) supplies. There was a positive association between the presence of Aeromonas and the bacterial indicator organisms. Households reporting at least one member with gastrointestinal symptoms in the month prior to sampling, were more likely to have Aeromonas spp. identified in their water supply than those households without symptoms (odds ratio 3.22, 95% CI 1.15-9.01, p = 0.021). Salmonella typhimurium was detected in one of 115 (0.9%) supplies. Legionella spp. and Campylobacter spp. were not detected. There were 50 supplies sampled for protozoa (sampling criteria: > or = 30 FC or > or = 60 ENT). Cryptosporidium oocysts were detected in 2 (4%) of these. Giardia was not detected. This study demonstrates that roof-collected rainwater systems provide potable supplies of relatively poor physiochemical and microbiological quality in the Auckland area. Further research is required on Aeromonas spp. as potential indicators of both microbiological quality and health risk along with design and maintenance strategies to minimise contamination of potable roof-collected rainwater supplies.     

WATER RE-USE - CAPTURING A WASTE RESOURCE

The east and south-east of England has the lowest rainfall in the UK, water resources are limited and under pressure through increased demand and population growth. In the late 1990's AW Innovation (the AW R&D group) developed a process that could produce high purity water from sewage effluent using membrane technology. In late 1999 Texas Utilities (TXU) signed a contract with Alpheus Environmental for the supply of high purity water for Peterborough Power Station. The novel treatment plant was built in 1999 - 2000 and opened in July 2000 by the Mayor of Peterborough. This paper is a review of the plant design, the technology used for the treatment process and a summary of the first four years of operation.
Changing from potable water to high purity water produced from sewage effluent has brought significant benefits for the power station resulting in higher purity steam generation while reducing chemical, power and effluent discharge costs. In addition Anglian Water is now saving 1,000 m³/day of potable water.     

Evaluation of Lake Vyrnwy within the Integrated Water Supply Systems of North West Water

ABSTRACT In 1992, the National Rivers Authority published a discussion document on the National Water Resource Strategy which highlighted the future probability of a water-supply deficit in the south-east and a surplus in the north and west of England and Wales. One suggestion for rectifying this imbalance was to divert Lake Vyrnwy water which, at present, supplies Liverpool. This would allow further regulation of the River Severn, and subsequent transfer to the River Thames. Joint investigations by the National Rivers Authority and North West Water have established the implications of this diversion on the existing water resources and supply systems of North West Water.
The studies considered (a) the relationship between increased regulation releases, and reduced direct supply rates from Lake Vyrnwy, (b) the investment and operating cost implications of replacing Lake Vyrnwy supplies from sources within the southern command zone or by transfer from the northern command zone, and (c) the potential operational difficulties.
The paper describes how each of these aspects has been addressed. The results demonstrate the necessity of evaluating Lake Vyrnwy as a component of the integrated water supply systems of North West Water, and of other parts of the country.     

Optimal water tariffs and supply augmentation for cost-of-service regulated water utilities

We describe how a common method for regulating water utilities, cost-of-service regulation, can both in theory and practice result in the premature and economically inefficient water supply augmentation. Using a dynamic model calibrated to demand and supply conditions in Sydney, Australia we show how to optimally determine the time to supply augment using a ‘golden rule’ that minimises the average volumetric price paid by consumers. Our results show that, the greater the water scarcity and the longer the operational life of the additional supply, the sooner is the optimal time to augment. Based on our findings, we recommend that price regulators of water utilities adopt an historical cost less depreciation basis for a regulated asset base and a fully flexible and dynamically efficient volumetric pricing that accounts for the marginal opportunity cost of water supplies.     

The Measurement of Plumbosolvency Propensity to Guide the Control of Lead in Tapwaters

A laboratory-scale lead-pipe rig has been developed into an accelerated test for 'plumbosolvency propensity'. High alkalinity water supplies from Anglian Water show either relatively high or low propensity characteristics which appear to be related to the form of the crystal deposit. These have been examined by scanning electron microscopy. The paper describes the uses of the test to (1) supplement random survey data, (2) investigate mixed waters, and (3) optimize orthophosphate dosing.     

The Control and Monitoring of Discharges by Biological Techniques

Traditionally, the control of discharges to UK surface waters has been achieved using a chemical-specific approach. There are, however, benefits in also applying toxicity-based consents to effluents of complex composition.
This paper describes the approach to direct toxicity assessment of discharges being developed by the Water Research Centre for and with, the National Rivers Authority.     

Reducing demands for potable water

Industry may be the biggest user of water, but this largely involves untreated and relatively cheap supplies, whereas the public water supply system is costly to install and maintain. Domestic demands on this treated water are significant and this article describes work at the UK Building Research Establishment on possible economies in this area, particularly in relation to the w.-c., where the scope for savings is considerable.