President Robert Mugabe's government has stopped short of declaring a national disaster, although the CPU is usually deployed in the wake of national disasters, such as floods and droughts.
The government said that in the past seven days nine people had died nationally from cholera, an easily treatable waterborne disease, but unofficially the numbers are thought to be much greater.
CPU director Madzudzo Pawadyira told Zimbabwe's local media that the agency had been mandated to provide clean water, even though this was the responsibility of the state-owned Zimbabwe National Water Authority (ZINWA). "We are coming in to help with the provision of water," he said.
The capital, Harare, including its central business district, has been without piped water for the past four days, while sewer bursts are being left unrepaired, resulting in raw sewerage running in the streets.
ZINWA confirmed that it has been pumping untreated sewage into Harare's water supply dam, Lake Chivero; when supplies are accessible, the water coming out of the taps often emits a pungent smell.
The UN children's agency, UNICEF, and the World Health Organisation have been assisting in the provision of drinking water, while the CPU is setting up cholera clinics in the capital's high-density suburbs and has embarked on educational programmes to prevent the disease from spreading.
A ban on vending food in public places has been imposed, and the shallow wells people have dug to get to water when the taps stopped running are being decontaminated; refuse, which has not been collected this year, will now be collected, the CPU said.
According to Harare's health director, Stanley Mongofa, "I can safely say we have been admitting a number of people suffering from the disease but no deaths have been recorded. Some might have died in their homes [that] we are not aware [of]."
An IRIN correspondent visited Harare's Beatrice Road Infectious Diseases Hospital this week, where 15 people had reportedly died from cholera, and found the facilities were stretched, with patients being treated in the hospital grounds because there were no more beds available.
"Some TB patients have been evacuated and the place is now catering for cholera patients. We are aware that the government is understating the number of patients who have died from cholera," a health worker, who declined to be named, told IRIN.
"We are looking at a very serious health disaster, whose effect the authorities may soon not be able to handle because it appears to be an uncontrollable outbreak," the health worker said.
Sesel Zvidzai, secretary for local government in the opposition Movement for Democratic Change, said ZINWA should cede the control of water supplies to local authorities, who had previously performed the task.
"ZINWA is not in a position to maintain water and sewer equipment, since they do not have engineers; all the engineers have deserted the water authority because of poor salaries."
Zvidzai said Masvingo in southeastern Zimbabwe, the only town that still retained control of its water treatment and distribution, had not suffered any cholera outbreaks because of the efficiency of its water management authority.