Swedish researchers have found that the bacteria used in wastewater treatment plants can “catch colds,” weakening their effectiveness.

Wastewater treatment plants use microscopic bacteria to break down pollutants in wastewater and purify the water.

Researchers from Chalmers University of Technology, Sweden found treatment plants that had higher concentrations of viruses reduced the effectiveness of the bacteria in carrying out their purification functions. The treatment plant essentially stops working as well as it could because of the presence of viruses – just like humans.

The study found that when more viruses were detected, more dissolved organic carbon was also detected in effluent, the water released by the plant into surrounding waterways. Increases in organic carbon mean more money, energy and materials must be spent to keep the treatment plant running as it should.