Koningshoeven abbey is one of only 13 places in the world to brew Trappist beer, and its products have won over drinkers around the world.

For all the commercial success, however, a nagging sense that money has triumphed over spirituality has prompted the monks to rethink their use of water after more than 130 years.

We have had to translate our faith into sustainability Father Isaac

The Cistercian monastery on the Dutch-Belgian border is the first brewery in western Europe to construct a plant-based water filtration system that avoids the current waste of seven litres of water for every litre of beer produced.

In a large greenhouse, 70 species, including ferns and other sub-tropical plants, sit above bins of waste water that flows through pipes from the brewery. The interaction of the micro-organisms on the plants’ roots and the bacteria in the water purifies it for reuse.

“We are praying seven times a day to praise the Lord for his creation, but we were not working in the right way to stop pollution,” said Father Isaac of his brewery. “We have had to translate our faith into sustainability.”

The hop garden at Koningshoeven abbey. Photograph: Craig Stennett/Alamy

Only beer brewed with a monastery’s walls is authentically Trappist, and the Koningshoeven abbey produces 10m litres (18m pints) a year.

It is one of just 13 abbeys producing Trappist beer. There are six in Belgium, two in the Netherlands and one each in Austria, the US, France, Italy and the UK.

It is hoped that the new system, which has been officially consecrated, willpurify around 450,000 litres every seven hours when fully operational without any need for human intervention.

The abbey in the Dutch village of Berkel-Enschot, in Noord-Brabant, also produces 43% of its electricity from solar panels, and the monks – who also make a popular cheese – drive electric cars when they need to leave the monastery.

The abbey plans to further reduce the monks’ ecological footprint in a less palatable way. “We want to be able to purify human waste water to turn it into drinking water,” said Father Isaac. “I feel a big responsibility for the next generation, and we need to ensure they inherit a cleaner world.”

• This article was amended on 31 December 2018. There are 13 abbeys brewing Trappist beer, not 12 as stated in an earlier version.