At least 16,000 residents in part of the central Colombian province of Meta are without potable water after the leftist FARC guerrillas dynamited a portion of a local aqueduct, media outlets said.
The people most heavily affected by the attack by the Revolutionary Armed Forces of Colombia, or FARC, were residents of the municipalities of Granada and Fuentedeoro.
The explosive charge was detonated on Saturday in a rural sector near Granada.
At least 40 percent of the Fuentedeoro urban area was left without potable water due to the blast, Mayor Guillermo Suarez told the Bogota daily El Tiempo.
For the moment, local residents are drawing their water from storage cisterns.
The attack comes after other actions by the FARC earlier in July, including an attack in the southern border province of Putumayo that spilled more than 5,700 barrels of oil from tanker trucks causing an environmental catastrophe.
The situation forced the government to order two battalions of army special forces troops to the area to undertake operations against the FARC.
Representatives of the Colombian government and the FARC have been holding peace talks in Havana since November 2012.