The US Air Force has admitted to “accidentally” releasing a massive amount of highly toxic chemicals into the sewer system of Colorado.

Peterson Air Force Base in Colorado Springs said Wednesday that it unintentionally released over 150,000 gallons (570,000 liters) of tainted water to the city’s sewers without having a clear understanding of the potential health hazards.

The water contained perfluorinated compounds, commonly referred to as PFCs, which may cause to prostate, kidney and testicular cancer, along with other illnesses, the base said.

PFCs are used in the firefighting foam which is widely used at military bases.

Steve Berry, a spokesman for Colorado Springs Utilities, said the toxic waste didn't contaminate the drinking water.

One of the storage tankers at Peterson air base (file photo)

Although the water passed through a treatment plant, the danger was still there as the plant was not meant to remove PFCs, according to Berry.

The leak occurred sometime in the past week, the Air Force said, adding that the storage tank that the tainted water was released from is still being investigated to find the cause. The incident was discovered during a routine check on October 12.

The tank holding the water was part of re-circulation system that sent the water back to a fire training area, officials noted.

So far two cases of PFC contamination have been reported in the well water of two nearby communities and officials are investigating whether they were related to the leak.

Following similar cases in August, the USAF struck a $6.2 million contract to replace the firefighting foam with an "environmentally responsible” one in order to reduce the risks.

The problem is not limited to US bases within the country’s borders.

Documents obtained under the US Freedom of Information Act point to years of accidents and neglect at American military forces abroad.

In Japan’s Okinawa Island, for example, Kadena Air Base has polluted local lands and water resources with dangerous chemicals such as arsenic, lead, polychlorinated biphenyls (PCBs), asbestos and dioxin.