"Most parts of Harare - including the city centre - did not get water yesterday amid claims by Zinwa staff that the authority had stopped pumping after it ran out of one of the essential chemicals," the Herald newspaper, a government mouthpiece, reported.
Residents in Chitungwiza, Zimbabwe's second city, were cited by the Agence France-Presse news agency as saying that they too were not receiving water supplies.
Locals were instead searching for water with pans and optimistically digging wells near their properties.
Chitungwiza has been at the centre of the epidemic.
Harare says that 425 people have died of the disease nationally since the outbreak in August.
A total of 11,071 cases have been recorded in the impoverished south east African country.
The UN said on Friday that the disease is also spreading into neighbouring Botswana and South Africa.
The UN Office for the Coordination of Humanitarian Affairs (OCHA) warned of an "alarming regional dimension" and said the health ministries of South Africa and Zimbabwe were working on co-ordination efforts together with the WHO.
"The rapid deterioration of the health service delivery system in Zimbabwe, the lack of adequate water supply, and lack of capacity to dispose solid waste and repair sewage blockages in most areas will continue to contribute to the escalation and spread of the outbreak," Elisabeth Byrs, the OCHA spokeswoman, said.
UN humanitarian agencies are working on the ground to ensure the delivery of medical supplies, clean drinking water and water purification kits.
Byrs said that basic hygiene kits comprising a bucket or jerry can, soap and water treatment tablets have been distributed to at least 4,000 households in the capital Harare.
Veronique Taveau, a Unicef spokeswoman, said that unlike previous outbreaks that mainly hit rural areas, the current epidemic is affecting densely-populated urban centres, "which leads to its rapid expansion and makes it harder to fight against the disease".
South Africa has reported seven cholera deaths over the last two weeks, all Zimbabweans or people who recently came from the country.
Phuti Seloba, health department spokesman in the South African border town of Musina, said that dozens of cholera patients from Zimbabwe enter the country every day.
Border river contaminated
South African health authorities have set up five cholera treatment centres along the border to handle the influx, he added.
But the Limpopo River, the natural border between Zimbabwe and South Africa which many Zimbabweans cross to reach the neighbouring country, was also confirmed as contaminated with Cholera on Monday.
Zimbabwe belatedly changed its tune on Thursday and asked for international help to fight the outbreak after long insisting that the situation was under control.
"With the coming of the rainy season, the situation could get worse," Edwin Muguti, deputy health minister, said.
"Our problems are quite simple. We need to be assisted."
Cholera is spread via water contaminated with feces and can potentially kill within hours.