is heating
She is heating the water.
¿Quién carajos está calentando la llave en su culo?
Who the hell is warming up the tap in his ass?
— Gangs of Wasseypur I (2012)
La luz del sol está calentando el agua.
Sunlight is heating the water.
Ella está calentando agua para el té.
She is heating water for tea.