Tokyo Suibotsu?!

This heartwarming story is set in the Tokyo Waterworks Bureau. To instill a sense of urgency in Mitsushima Nagisa, a new waterworks employee who isn't taking her job seriously, her supervisor, Izumizawa Kotaro, and her department head, Yamakawa Akira, tell her that Tokyo has been flooded due to a fictional water main break. The story unfolds from there. (Source: Japanese = natalie.mu || Translation = Thyella at MyDramaList)