Sanitation and water regeneration, keys to the water resilience of cities


Oliver Thansan
Oliver Thansan
19 November 2023 Sunday 16:12
6 Reads
Sanitation and water regeneration, keys to the water resilience of cities


Moving towards a more sustainable world requires everyone's effort. The climate and natural resource emergency poses a challenge to essential services such as drinking water and sanitation, which are key to the sustainability of cities. Taking care of them is essential for people's health and the preservation of the environment.

On November 19, World Sanitation (or Toilet) Day is celebrated, with the motto "Accelerate change". There are still 3.5 billion people in the world who live without safe toilets and 2.2 billion without clean water. Children are the most vulnerable to the triple threat of unsafe water, unsafe sanitation and poor hygiene.

In 2015, the United Nations (UN) approved the Sustainable Development Goals (SDGs), with the aim of eradicating poverty and guaranteeing minimum services to the world population. For everyone to have safe drinking water and toilets by 2030—the promise of SDG 6—the world must work, on average, five times faster on sanitation goals, six times faster on water goals and three times faster in hygiene, according to the UN. In many countries, the rate of acceleration must be several times higher than the average.

Based on the availability of water and the innovation brought about by the hydraulic siphon and domestic cisterns connected to a common drainage network, sanitation is a lifesaver that prevents the transmission of diseases and facilitates the healthiness of spaces. It is a cornerstone of public health and plays a fundamental role in protecting the environment.

Climate change, with extreme weather events (floods and droughts) and rising sea levels, can damage a vital system for cities. In our country, the current context of drought and structural water scarcity in the metropolitan area of ​​Barcelona forces us to look for, and above all, to urgently implement effective and sustainable solutions. The Catalan Water Agency (ACA) estimates that the current water deficit in the metropolitan region is 2 m3/s, equivalent to 60 hm3 per year. A deficit that will double in 2027 (4 m3/s and around 125 hm3 per year) and will reach 6 m3/s in 2039 (approximately 190 hm3 per year). Taking into account that during the year 2022 a total of 217 hm3 of drinking water was distributed in the metropolitan area to satisfy all the demand, this region is clearly in a structural situation of water emergency.

Aigües de Barcelona is betting on new sources such as regenerated water, which is water that comes out of treatment plants and undergoes additional treatment to be suitable for new uses, such as urban, environmental, industrial or agricultural. The company, an international benchmark in the circular economy, regenerated 50 hm3 of water in 2022, the equivalent of the water consumption of nearly 1,250,000 people for a year. Regeneration makes it possible not to depend on rain, to reduce the extraction of water from surface and underground resources (rivers and aquifers) and also, very importantly, to reduce the water footprint, since it does not need to be transported from anywhere else. The energy cost of reusing regenerated water is much lower than that of desalination.

Regenerated water is currently being pumped from the Baix Llobregat regeneration station upstream to Molins de Rei to be reused as potable water. In this way, regenerated water is brought to the river so that the Sant Joan Despí water treatment plant captures it downstream and treats it again to turn it into drinking water and continue the water cycle.

So, in a drought situation like the current one, 19% of the water resource corresponds to surface water (mainly rivers), 23% to underground water (wells and aquifers), 33% to desalinated water and 25 % to regenerated water; while in a normal year, 95% of the water resources for the metropolis of Barcelona are linked to climatology, that is, surface and underground water.

The hummingbird is the symbol of this year's World Sanitation Day, using an old Guarani fable in which this little bird wants to put out a big fire by carrying drops of water in its beak. A powerful symbol that shows that our action can help solve a big problem.

Climate change forces us as a society and cities to transform ourselves to be more resilient and sustainable. To accelerate this change, everyone needs to do their part.