The incident took place on Tuesday and the body of the victim, identified as Kinjal Shah (21), a resident of Vasai, was recovered later from an under-construction site, Inspector P D Kolhe of Arnala Coastal Police Station said.
The accused, Devendra Bhosle, who worked as a waiter at a hotel in Colaba of south Mumbai was reportedly enraged after seeing his girlfriend with another boy and planned to kill her, police said.
He took Kinjal to the waterfalls in Vasai and allegedly drowned her. Later, he put the body in an autorickshaw, told the driver that she was unwell and went to Virar. He then dumped the body near an under-construction site adjacent to her house, they said.