The luxury of drinking water in the face of drought and serious pollution

Every year on this date the UN reminds us that 2.2 billion people in the world (26% of the global population) still do not have access to drinking water (in contrast, 4.3 billion already own a smartphone). There are numerous technological proposals to expand access to drinking water in these places where it is not yet common, such as steam condensation or desalination, an energy-intensive option and, therefore, in principle it is more expensive than purifying it. In addition to who is missing, the increase in the urban population, the challenges of climate change such as droughts orWater pollution increases challenges not only in developing countries, but also in the so-called first world. Problemsfuture commons can be summarized in two: scarcity and quality.

New treatments

In any country in Europe or North America, it is easy to turn on a tap and have water come out, but do we know how it got here? Surface water and aquifer water must be extracted and passed through a treatment in some Drinking Water Treatment Stations (ETAP). Basically «the conventional process that is applied in Spain is divided into several phases. First, a physical-chemical treatment is carried out that improves the conditions of the water to adapt it to the plant process. For this, different reagents are used that, first, oxidize, that is, break down the molecules of organic matter and other compounds, and then coagulate or, in other words, bring the particles together so that they weigh and precipitate to the bottom. The next phase consists of removing the sludge of particles from the bottom and then moving on to the sand filtration process, which is done to eliminate any conglomerate of united particles that are small and have not precipitated,” explains Javier García Castillo, head of the purification of the Facsa company.

New contaminants such as drugs, cocaine, nitrates or microplastics have been detected

But things get complicated when it comes to an area with drought or near the coast where seawater invades both rivers and aquifers. In the north of the peninsula, which has a large amount of surface water and where it rains more, the process will always cost less. «The quality of water is uneven and the more degraded the source is, the more it costs to make it drinkable. There are two expenses, one has to do with the origin of the water (surface or aquifer). In the latter case, If the extraction depth exceeds 500 meters, the costs of making it drinkable begin to resemble desalination. Furthermore, near the coast the aquifers have problems due to the entry of seawater. Then we must take into account the degree of contamination: the more products found, the more expensive the process will be and, in general, the surface water and aquifers are increasingly in worse condition. Even so, it can be said that water rates in Spain are economical compared to those of other EU countries such as Germany and Holland,” says Jaime Lora, from the University Institute of Industrial, Radiophysical and Environmental Safety of the Polytechnic University of Valencia. .

If the extraction is done at a depth of more than 500 meters, the cost is similar to desalination

The detection of new contaminants in water is increasingly making purification more technical. Famous is the study that stated a few years ago that the eels in the Thames River in London were becoming hyperactive due to the high concentrations of cocaine in its waters. The drugs we consume (for example, estrogens in contraceptives cause sex changes in fish), nitrates from agricultural or industrial activity, microplastics, and even byproducts from water disinfection itself are part of the list of new contaminants found in rivers and that are increasingly controlled in treatment plants and water treatment plants. We must not forget that the purified waters upstream will be those that will be captured to feed the uses of localities and industry downstream.

«In recent years, there have been many advances in the detection of certain contaminants, and regulations have become more demanding and restrictive in limiting their presence in water. For all these particles, Conventional purification is not useful, so the DWTPs have been adding treatments. For organic compounds such as drugs or hormones, oxidation is enhanced with new products such as ozone. Molecules are broken and then they must be eliminated. For this reason, after filtration with sand, activated carbon is added to adsorb (with d, which means to retain or concentrate a solid body) on its surface, the molecules of a fluid or the substances dissolved or dispersed in it). It can then be completed with advanced oxidation that, in addition to ozone, adds hydrogen peroxide or ultraviolet light and in the final elimination part, a treatment with membranes can be added to the active carbon.

2,200 MILLION people in the world still do not have guaranteed access to drinking water with minimum quality

It is about placing a barrier so that only clean water passes through it, as happens in desalination. Of course, the more technological processes are added, the more expensive it is to make drinkable, potentially doubling the expense,” explains the Facsa technician. And the more drought, alert, the more expensive the purification is, because the water usually has poorer quality. Something that is already happening in Catalonia.

Missing data

The DWTPs are being renewed little by little, but according to the Facsa technician, there is no official record to know the exact situation of water treatment in Spain. «In 2015-2016, an attempt was made to carry out a census of water treatment plants and it was impossible. If we could know the number of facilities there are and what type of treatment they apply, we could know how much drinking water is produced and the real demand, in case we are at the limit of capacity. We don't know if they are obsolete, but in that century and at that time pesticides were not analyzed. If it is possible to know the technology they apply, you can also see the path that can be taken to improve the treatments applied,” argues the Facsa technician.

As has been said, the purification processes are redefined to improve the quality of drinking water. In Spain, the latest regulations, RD3/2023, include the need to carry out controls to detect the presence of microplastics and emerging substances, and more restrictive limits for contaminants such as arsenic, lead and trihalomethanes. The latter are disinfection byproducts that are controlled because, although disinfection is basic in water treatment because it prevents the appearance and transmission of viral diseases and diarrhea, the byproducts can pose a risk. «The first byproducts that were identified in drinking water were trihalomethanes, in 1974.

Since then, various studies have been carried out and the association with bladder cancer began to be investigated,” says Cristina Villanueva, ISGlobal researcher and author of a study on these substances, who also assures that the levels in Europe and North America are very low and, therefore, the water is safe. However, in developing countries the same cannot be guaranteed in all cases. «Among the 89 countries that do regulate these disinfection by-products (of the 116 studied), the maximum levels allowed range between 25 μg/L in Denmark and 1,000 μg/L in Botswana. The limit established by the EU is 100 μg/L. Another relevant fact is the absence of routine controls in many of the countries studied, since they are only carried out in a total of 47. These data show the enormous inequalities between high-income and low-income countries when it comes not only “to regulate the concentrations of disinfection byproducts, but to monitor and guarantee compliance with chemical quality standards,” states their study.

The water cycleT. GallardoThe reason


The fact that purification needs to incorporate more technology every day also means that it becomes more expensive and that its price, in some cases, is close to that of desalinated water. This can currently reach 70 euro cents per m3 (although it is going down), while Potable water in good conditions costs only 0.10 cents. «As surface water increasingly requires more treatment, water treatment plants have already reached energy consumption of 1 kWh per m³ and continues to rise. At the same time, the waters in the aquifers from which they are extracted are deeper or more contaminants must be removed… Meanwhile, desalinated water continues to drop in consumption (3.8 kWh per m³) and price,” Lora specifies.

0.10 euros is the minimum that purified water costs, compared to a maximum of 0.70 euros for desalinated water.

There is one more important variable in the drinking water cycle until it reaches our taps: the supply network. And this, in some cases, still causes problems in the first world as well. Recently, the Biden government has approved a 15 billion euro plan to change the more than nine million lead pipes in the country that have caused damage to the health of the inhabitants of several locations in the country such as Michigan. Lead is a neurotoxin. It affects the central and peripheral nervous system, the digestive and immune system, the kidneys, the heart and also the reproductive system. Before the 1980s, when they were banned in Spain, it was common to have these pipes in homes and, although they have been replaced by PVC ones, it is estimated that up to 10% of them may remain in large cities like Madrid.