What criteria should we use to make water drinkable?
Water is essential to life. It is the most strictly regulated food product in France. But how can we be sure that it is drinkable and, in particular, what criteria should we use to determine that it is safe to drink? Some answers follow.
Water is not a laughing matter. In France, water must meet no less than 54 quality criteria – defined by the Ministry of Health and based on recommendations from the World Health Organization — to be considered “drinkable.” What are these criteria? What controls are performed?
Potable water is water that we can drink without any health risks
First of all, two kinds of substances are defined: pathogens and potentially undesirable substances. Based on this description and standards in effect, water must not contain any parasites or germs (bacteria or virus) that could pose a threat in order to be considered potable. Limit values for substances considered to be undesirable or toxic – such as nitrates and phosphates – have been established based on a precautionary principle and on daily consumption levels that apply to the most vulnerable populations. These limits are revised regularly in accordance with changing scientific knowledge.
A system that features strict controls
Based on these 54 criteria and following the treatment of water, rigorous, unscheduled checks are conducted both by the French Department of Health and Social Security (DDAS) and the operators of water production and wastewater treatment plants, such as Lyonnaise des Eaux. Samples are taken from all drinking water production and distribution facilities. Operators take daily samples at each plant and at various points in the distribution network. These samples are then analyzed in the laboratory. Some Lyonnaise des Eaux facilities are even equipped with sensors that analyze water continuously and trigger an alarm automatically in the event of an anomaly. In 2008, more than 99% of the analyses conducted by French health authorities of water produced and distributed by Lyonnaise des Eaux complied with French regulation, which is among the strictest in the world.
While micro-pollutants and drug residues receive considerable attention today, only trace amounts of these substances are present in water, in extremely low levels of approximately a few nanograms per liter. Through initiatives such as the Lyonnaise des Eaux “dragonfly zones” and research efforts such as the Ampères program conducted jointly with Cemagref, SUEZ ENVIRONNEMENT is working actively to improve knowledge and performance in controlling micro-pollutants.
Developing technologies to fight new sources of pollution
Protecting freshwater resources from nitrate pollution is also a central concern. Half of the world’s freshwater reserves are polluted, affecting both developed and developing countries. Most of this pollution comes from agriculture. It is very expensive to treat polluted water, which is defined as containing more than 50 mg/l of nitrates, a threshold set by the 12 December 1991 European Directive. There is one way to address the degradation of water resources and avoid excessive treatment costs: soil aquifer treatment (SAT). This ecological process uses the soil’s purification capabilities to improve the quality of raw water. By working directly with the underground water resource, SAT is a less expensive and more environmentally sound technique than traditional treatment, which uses chemical reagents.
Water that is drinkable and tastes good
For potable water to be pleasant to drink, it must be clear and smell and taste good. And to taste good, it must contain a minimum of trace elements and dissolved mineral salts (between 0.1 – 0.5 grams/liter), which are essential to the body. This is where CIRSEE comes in. Drawing on more than 20 years of experience, researchers at CIRSEE, the SUEZ ENVIRONNEMENT International Research Center on Water and the Environment, SUEZ ENVIRONNEMENT’s primary center of expertise, have developed the “Tastes and Smells of Drinking Water” service for the company’s operators. Based on unique know-how, this service can detect, characterize and treat the compounds that generate tastes and smells in drinking water. For example, in the Ile-de-France region (Presqu’île de Gennevilliers), a taste observatory and a panel composed of 180 consumers, trained to recognize tastes and smells, were established to improve the quality of water flavor.
