Complex sentence: The Himayat Sagar and Osman Sagar reservoirs provided continuous water supply to the twin cities of Hyderabad and Secunderabad until recent but due to growth in population it was not sufficient for water supply to Hyderabad city.
Split into simpler sentences: The Himayat Sagar and Osman Sagar reservoirs provided continuous water supply to the twin cities of Hyderabad and Secunderabad until recently. Due to population growth it was not sufficient for water supply to Hyderabad city.