Research & Development

Research & Development of Drinking Water

Drinking water or potable water is water of sufficiently high quality that it can be consumed or used without risk of immediate or long term harm. In most developed countries, the water supplied to households, commerce and industry is all of drinking water standard, even though only a very small proportion (often 5% or less) is actually consumed or used in food preparation.

Over large parts of the world, humans have inadequate access to potable water and use sources contaminated with disease vectors, pathogens or unacceptable levels of dissolved chemicals or suspended solids. Such water is not potable and drinking or using such water in food preparation leads to widespread acute and chronic illness and is a major cause of death in many countries.

Typically, water supply networks deliver potable water, whether it is to be used for drinking, washing or landscape irrigation. One counterexample is urban China, where drinking water can optionally be delivered by a separate tap.

Water quality and contaminants

Throughout most of the world, the most common contamination of raw water sources is from human sewage and in particular human faecal pathogens and parasites. In 2006, waterborne diseases were estimated to cause 1.8 million deaths each year while about 1.1 billion people lacked proper drinking water.[6]. It is clear that people in the developing world need to have access to good quality water in sufficient quantity, water purification technology and availability and distribution systems for water. In many parts of the world the only sources of water are from small streams often directly contaminated by sewage.

Most water requires some type of treatment before use, even water from deep wells or springs. The extent of treatment depends on the source of the water. Appropriate technology options in water treatment include both community-scale and household-scale point-of-use (POU) designs.

The most reliable way to kill microbial pathogenic agents is to heat water to a rolling boil[8] but this requires abundant sources of fuel and is very onerous on the households, especially where it is difficult to store boiled water in sterile conditions. Other techniques, such filtration, chemical disinfection, and exposure to ultraviolet radiation (including solar UV) have been demonstrated in an array of randomized control trials to significantly reduce levels of water-borne disease among users in low-income countries[9], but these suffer from the same problems as boiling methods.

Over the past decade, an increasing number of field-based studies have been undertaken to determine the success of POU measures in reducing waterborne disease. The ability of POU options to reduce disease is a function of both their ability to remove microbial pathogens if properly applied and such social factors as ease of use and cultural appropriateness. Technologies may generate more (or less) health benefit than their lab-based microbial removal performance would suggest.

The current priority of the proponents of POU treatment is to reach large numbers of low-income households on a sustainable basis. Few POU measures have reached significant scale thus far, but efforts to promote and commercially distribute these products to the world's poor have only been under way for a few years.

Parameters for drinking water quality typically fall under two categories: chemical/physical and microbiological. Chemical/physical parameters include heavy metals, trace organic compounds, total suspended solids (TSS), and turbidity. Microbiological parameters include Coliform bacteria, E. coli, and specific pathogenic species of bacteria (such as cholera-causing Vibrio cholerae), viruses, and protozoan parasites.

Chemical parameters tend to pose more of a chronic health risk through buildup of heavy metals although some components like nitrates/nitrites and arsenic may have a more immediate impact. Physical parameters affect the aesthetics and taste of the drinking water and may complicate the removal of microbial pathogens.

Originally, fecal contamination was determined with the presence of coliform bacteria, a convenient marker for a class of harmful fecal pathogens. The presence of fecal coliforms (like E. Coli) serves as an indication of contamination by sewage. Additional contaminants include protozoan oocysts such as Cryptosporidium sp., Giardia lamblia, Legionella, and viruses (enteric). Microbial pathogenic parameters are typically of greatest concern because of their immediate health risk.

70% of the Earth's surface is covered by water. Water is available almost everywhere if proper methods are used to get it.

Sources where water may be obtained include:

1. ground sources such as groundwater, hyporheic zones and aquifers.
2. precipitation which includes rain, hail, snow, fog, etc.
3. surface water such as rivers, streams, glaciers
4. biological sources such as plants.
5. the sea through desalination

Access to drinkable water is a complicated, yet vital issue. There is great diversity in access not only between countries but within countries and even cities.

Cost is the major limiting factor of access to drinkable water.

The most efficient way to transport and deliver potable water is through pipes. However, this requires a enormous up front infrastructure costs. Further the high continual operating costs mean many systems fall into disrepair in both developed and undeveloped countries. The cost to replace aging water and sanitation infrastructure may be as high as 200 billion dollars a year. Further, Leakage of pipes reduces access to water. Leakage rates of 50% are not uncommon in urban systems.

Because of the high initial investments, many debt impoverished nations cannot afford to develop this infrastructure. So people in these areas end up paying a much higher percentage of their income on water. 2003 statistics from El Salvador, for example, indicate that the poorest 20% of households spend more than 10% of their total income on water. In the United Kingdom authorities define spending of more that 3% of income on water as hardship.

The Millennium Development Goal of halving the proportion of people without access to safe drinking water between 1990 and 2015 will probably be reached. Although some countries still face enormous challenges.

Rural communities are the furthest from meeting the 2015 MDGs drinking water target. Globally Only 27% of the rural population has water piped directly to their homes and 24% rely on unimproved sources. Of the 884 million people without access to an improved water source 746 million people (84%) live in rural areas. Sub-Saharan Africa has made the least progress in improved water sources since 1990, improving only 9% to 2006. In contrast the Eastern Asian region saw a dramatic drop from 45% to 9% reliance on unimproved water in the same time period.

Drinking water regulation

European UnionThe EU sets legislation on drinking water quality in addition to factors such as how, where and when water can be extracted from the environment. Directive 2000/60/EC of the European Parliament and of the Council of 23 October 2000 establishing a framework for Community action in the field of water policy, known as the water framework directive, is the primary piece of legislation governing drinking water.

Each member state is responsible for establishing the required policing measures to ensure that the legislation is implemented. For example, in the UK the Drinking Water Inspectorate polices the water companies.

United States of America In the United States, the Environmental Protection Agency (EPA) sets standards for tap and public water systems under the Safe Drinking Water Act (SDWA).[40] The Food and Drug Administration (FDA) regulates bottled water as a food product under the Federal Food, Drug, and Cosmetic Act (FFDCA).[41] Bottled water is not necessarily more pure, or more tested, than public tap water.