The boys went to the Lower Manair Dam (LMD) reservoir this morning to have a bath in order to get some respite from the scorching heat, they said.
However, while enjoying the water, they got drowned in the reservoir at around 11.30 AM, Karimnagar Deputy Superintendent of Police J Rama Rao said.
Some other boys standing near the reservoir informed police who rushed to the spot, but by that time the boys had drowned, he said.
The bodies were later fished out and sent to hospital for post-mortem, he said.