When considering if water should be free at the point of use, it is perhaps more pertinent to look at why we have to pay for our water supply. It is widely known that the Earth’s surface, and to a lesser extent, ground water is intrinsic to a cycle in which it falls as rain or snow before being stored in oceans, reservoirs, rivers or as ground water. Under the sun’s influence, a proportion of this stored water evaporates and condenses to fall as rain or snow once more. The total volume in this water cycle remains constant to a large extent. The largest volume of stored water is found within the oceans and because of its high salinity, is undrinkable. In order to utilise sea-water for consumption it is necessary to install desalination units which are costly in both set-up and long-term energy use. Drinking untreated rainwater is inadvisable because of contamination by airborne pollutants and the consumption of water stored in reservoirs or rivers carries the risk of infection from microorganisms. In order to prevent disease, it is therefore necessary that all water intended for human consumption is treated in some way.
The London cholera outbreak – a link between dirty water and disease
Cholera is a waterborne disease caused by Vibrio cholerae, a Gram-negative bacterium that produces a toxin which results in severe vomiting and diarrhoea. If untreated, the infection can result in death within several hours due to massive dehydration and electrolyte imbalance. Prior to the 1849 cholera outbreak in London, there was no known link between disease and contaminated drinking water. Indeed, many of the medical profession at that time continued to reject the theories of Doctor John Snow, who made the connection between a street pump in Broad Street in London and the eventual deaths of in excess of seven thousand people (Bingham, et al. 2004). Upon examination, Snow investigated the drinking water from different origins and concluded that the water from the Broad Street pump was contaminated by sewage. He further suggested that this contamination was responsible for the outbreak (Snow, 1855). The causative organism, V. cholerae, was first isolated and described by Robert Koch in 1883 (Madigan, et al. 2000). In developed countries, cholera has been largely eliminated mainly as a result of efficient sanitation and the purification of drinking water.
Other disease-causing water-borne microorganisms
Most disease-causing microorganisms found in drinking water are associated with gastrointestinal disturbances though in many instances, a relatively high number of microbial cells are required for the transmission of disease. Waterborne microbes can comprise bacteria, viruses or protozoa. Bacteria that can survive in water and cause disease include Vibio cholerae (cholera, as outlined above), Escherichia coli, Salmonella typhi (typhoid fever) and Legionella pneumoni (Legionnaire’s disease). Waterborne disease-causing viruses include poliovirus (polio) and picornavirus (hepatitis A). More widespread than viruses are the waterborne protozoa Giardia lamblia and Cryptosporidium parvum and it was the latter that was the causative agent in the largest ever recorded outbreak of disease caused by a waterborne organism (Madigan, et al 2000). In Milwaukee, Wisconsin (1993), there was a cryptosporidiosis epidemic affecting approximately 403,000 people. This was thought to have been caused by contamination of water run-off by the excrement of dairy cattle. The outbreak was eventually responsible for 54 deaths (Mendez-Hermida, et al. 2007).
Water treatment as a means to prevent disease
As mentioned earlier, all water intended for human consumption requires prior treatment in order for it to be safe. Typically, drinking water in the UK is drawn from surface storage areas such as reservoirs. This is passed through large-mesh filters to remove items like plant matter. Air is added at this stage primarily to remove gas and metal salts. The water is then passed through a coagulation unit where ferric or aluminium sulphate is added to form a ‘floc’. This has the effect of removing small particulate matter such as bacteria and minute organic debris. The floc and sediment it has trapped is then removed. At this point the water is clarified by passing it through several layers of sand. These combined steps in the purification process effectively remove more than 99% of the bacteria contained in the water (Madigan, et al. 2000). Finally, small amounts of chlorine (as sodium or calcium hypochlorite or chlorine gas) are added to the water in order to kill any remaining microorganisms and neutralise organic compounds. In many areas of the UK this last stage is followed by an adjustment in the pH level of the water; a measure to protect the pipes through which the water passes (Severn Trent, 2001).
In order to prevent disease from sewage contamination, it is necessary to have stringent measures in place to effectively manage human waste. Water can be ‘reclaimed’ from the process and returned to the watercourse via rivers and in some cases can enter the purification route once more to become drinking water. Waste travels directly to sewage treatment works via a network of pipes. On arrival at the plant the raw waste is passed through large filters which remove large particles like paper and plastic. The waste is then screened further by passing through channels. This process removes smaller items such as dirt and grit which may have become trapped in the waste. The sewage is allowed to settle in large settling tanks. Treatment can then follow one of two distinct paths. Breakdown by anoxic digestion is carried out by a variety of different bacterial species including Methanosaeta sp. and other methanogenic species (Stams, 1994). The by-products of this digestion are methane (CO4) and carbon dioxide (CO2). The digested matter is then either incinerated or used as fertiliser. The alternative process is aerobic digestion which incorporates either a trickling filter or a layer of activated sludge. Trickling filters are simply beds of small stones onto which the waste is sprayed. The waste gradually falls through the bed during which organic breakdown is carried out by bacteria. In more common use is the activated sludge method. In this process, the waste is mixed together with a biofilm-forming bacterial species such as Zoogloea ramigera whilst being aerated in a large tank. This process results in floc formation, some of which is returned to the tank, the remainder being transferred to a sludge digester. These combined processes have the effect of reducing the bacterial count of the water by approximately 95% (Madigan, et al. 2000). Water recovered by these processes can then be purified for use as drinking water.
The water industry in the UK
The turning point with respect to water supply in the UK was the Public Health Act of 1848. The act made local ‘boards’ responsible for sewage and water supply to the residents in their area. The first of the boards to publish an annual report was the Metropolitan Water Board in 1890 (Drinking Water Inspectorate, 2007). The water industry is largely overseen by the Department for Food, Environment and Rural Affairs (Defra). Regulation is achieved with the assistance of the Drinking Water Inspectorate (DWI), whose task is to regulate drinking water quality and the Water Services Regulation Authority (Ofwat) whose concern is largely the economic aspects of the industry. Water UK represents the interests of those involved in the water industry itself. The industry was privatised by Act of Parliament in 1989 at which time it had a collective debt of £5 bn. This was ‘written off’ by the Government with a further £1.6 bn being invested (Ofwat). The latest water act (the Water Act, 2003) makes provision for licensing and compensation. In its annual report on the standard of drinking water, the DWI reported that the overall standard was in line with European directives, with 99.96% of all tests meeting those directives. However, the report went on to say that there had been an increase in the level of Escherichia coli in reservoir samples tested, most likely as a direct result of ‘unsatisfactory reservoir maintenance’ (DWI, 2006).
The average price paid by households in the UK is currently £285 per annum. This is set to rise to £295 per annum by the end of the 2009/10 charging period. This can be broken down into £155 for sewage and waste water and £140 for the provision of safe drinking water. The water industries had requested a 6.2% rise with a 4.2% increase being permitted by Ofwat.
The volume of water within the Earth’s water cycle remains largely consistent with water being stored in oceans, rivers and reservoirs. However, water obtained from these sources is, on the whole, unsafe for human consumption. To make this water available to drink, it has to go through a variety of processes, each involving considerable investment both financial and in respect of time spent in treatment. The cost to the water industry over the next 5 years is likely to be in the order of £16.8 bn. (Ofwat, 2004) and with none of that funding is met by central government, it is the consumer who has to pay the bill.