Bat boxes have been installed at a water treatment works in Kent to encourage the animals to roost at the site.
The 10 boxes are now on trees at Southern Water's Burham Water Treatment Works in Rochester.
Kathy Halsall, bat specialist and ecologist at Southern Water, said: "Bats are most active between May and September, so we'll check [then] for signs of activity to see if the bats like the new boxes."
The number of bats roosting in one box could range from one to eight, Ms Halsall said.
Tree-climbing surveys were also carried out on trees at the site as they had to be removed as part of essential maintenance work.
The surveys checked to make sure no bats would be disturbed before the trees were removed.