One of the Sustainable development Goals is to ensure the availability of water, its sustainable management and the use of the most appropriate techniques for sanitation according to the importance of the population centres. In my latest book on "Ecology, Climate Change and the Sixth Extinction" (McGraw Hill 2021) I state that "the management of water is a priority aspect for the development integral aspect of society, agriculture, industry, etc.

At the regional level, it is necessary to adopt integrated management schemes for river basin plans, or hydrological plans in the islands, which allow for the recovery and administration of the natural water cycle;.... it is essential to establish schemes for its sustainable use, diversify sources, reduce and minimise polluting discharges, and purify and recycle water as one more product of the circular Economics ".

This is what I have come to call applying a system of water management based on three "R's": Reduce consumption in all consumptive uses, agricultural, domestic, industrial, recreational, etc.; purify and regenerate water; and reuse regenerated water for certain agricultural uses, irrigation of parks and gardens, irrigation of extensive livestock farms, irrigation of golf courses, etc. At final, reduce water consumption in all sectors, as one of the measures aimed at mitigating climate change. Improving water use efficiency is a measure core topic that can contribute to reducing overall water stress in a region, especially in a limited region such as an island system where there is no water transfer option, provided that this also entails a parallel reduction in water abstraction.

Increasing water use efficiency over time means using less water for the same output, thus decoupling economic growth from water use in the main water-using sectors resource. Agriculture tends to have a much lower water use efficiency than other productive sectors, which means that a country's economic structure is usually largely affected by water use efficiency. Increasing water productivity in agriculture is therefore a key intervention to improve water use efficiency, especially in agriculture-dependent countries. Agriculture and livestock account for about 70% of water consumption. Therefore, one of the major challenges for most advanced societies is how to increase food production with less water consumption.

The Food and Agriculture Organization of the United Nations (FAO) works with countries to ensure that water use in agriculture is more efficient, productive and environmentally friendly. This involves producing more food using less water, building agricultural production systems to cope with floods and droughts, and applying water technologies that protect the environment. One of the most serious threats to sustainable development is water stress. The extraction of an excessive amount of freshwater from natural sources compared to available freshwater resources can have devastating consequences for the environment, such as dry rivers, overexploited aquifers (Doñana NP), and saline intrusion in coastal systems.

In southern European countries, Spain is one of the most severely water-stressed countries (World Resources Institute) because it consumes more water per capita per day for domestic use, and furthermore, this demand has been increasing due to economic development , urban expansion, tourism and agriculture. Approximately half of the Spanish population, some 22 million, suffers from water stress. Moreover, it is a paradox that Spain is one of the first European countries with the highest issue losses in its network distribution. The Netherlands, which does not suffer from water scarcity, has a water leakage volume of 5%, which is considered the technical minimum admissible, Germany has losses of 7%, and Austria has losses of 9%.

In Spain, real water losses in public urban supply networks due to leaks, breaks and breakdowns were estimated at 678 cubic hectometres, which represented 15.7% of the total water supplied to these networks (Ministry of Agriculture, Food and the Environment). Cantabria and Extremadura are at the head of the Autonomous Communities in terms of volume of water loss, with leaks of 39.2% and 37.8% -respectively- of the water distributed (INE). challenge The different administrations, within the scope of their competences, have an important role to play in the management of water as a basic sustainable resource both in agricultural policies and in the care and operational monitoring of distribution networks in rural and urban areas.