Water reuse

Water reuse is the use of reclaimed water, that is, wastewater that has been treated and given an additional reconditioning step, for purposes that do not require drinking water quality. These uses include agricultural irrigation, certain industrial processes, irrigation of urban green areas, street cleaning and aquifer recharge.

Reuse is one of the most effective levers against water scarcity and water stress, because it replaces freshwater consumption with a resource that would otherwise be discharged. It is part of the circular water economy approach, which seeks to close the water cycle instead of treating water as a single use resource.

Reclaimed water: from waste to resource

Reclaimed water is not the same as simply treated wastewater. Treatment removes the pollutant load so the water can be safely discharged to the environment; reclamation adds complementary steps (filtration, disinfection and, depending on the use, removal of further contaminants) so the water reaches the quality required by its destination. Each use has different requirements: irrigating a crop eaten raw is more demanding than irrigating a golf course.

Regulatory framework in the European Union

At European level, Regulation (EU) 2020/741 on minimum requirements for water reuse specifically governs the use of reclaimed water for agricultural irrigation. Adopted in 2020, it has applied since 26 June 2023. It sets minimum quality and monitoring requirements, the obligation to draw up a risk management plan, and requires a permit to produce and supply reclaimed water for agriculture.

Regulatory framework in Spain

In Spain, reuse is governed by Royal Decree 1085/2024 of 22 October, which approved the Water Reuse Regulation, amended several royal decrees on water management and repealed the earlier Royal Decree 1620/2007. It has been in force since 24 October 2024.

The new rules align the Spanish framework with the European Regulation, set out the permitted uses of reclaimed water by category (urban, agricultural, industrial and others) with their quality classes and maximum admissible values, and tighten monitoring requirements. They also explicitly prohibit certain destinations on health grounds, such as recreational use as bathing water, the farming of filter feeding molluscs in aquaculture, and use in hospital facilities.

Why it matters to companies

For a water intensive company, reuse is both a resilience and a cost saving measure. It reduces dependence on external abstraction, improves the water security of operations and eases pressure on the water bodies of the catchment. Measuring the water footprint is the step that tells you where reuse pays off and by how much. It also carries growing weight in sustainability reporting frameworks, which ask how the organisation manages water in stressed areas.

Manage your water with Manglai

Reusing water only makes sense if you know how much you consume and where. With Manglai's water footprint module you can measure consumption site by site and spot reuse opportunities across your value chain.