If this continues, people will be at an ever-higher risk of contracting diseases which are incurable by existing antibiotics from swimming in the sea or other seemingly innocuous activities, a report said.
"Around the world, discharge from municipal, agricultural and industrial waste in the environment means it is common to find antibiotic concentrations in many rivers, sediments and soils," the study found.
"It is steadily driving the evolution of resistant bacteria," it said. "A drug that once protected our health is now in danger of very quietly destroying it."
The report, "Frontiers 2017", was released at the UN Environment Assembly, the highest-level gathering on matters concerning the environment.
Health watchdogs are already deeply worried about the dwindling armoury of weapons against germs.
A report in 2014 warned that drug-resistant infections might kill 10 million people a year by 2050, making it the leading cause of death, over heart disease and cancer.
Bacteria acquire drug resistance partly by exposure to antibiotics.
To survive the drug onslaught, bacteria can transfer, even between different species, genes that confer immunity. They can pass these genes on to future generations, or DNA can mutate spontaneously.