Harare residents have been taking water from wells during the outbreak
Authorities in Zimbabwe have declared a cholera outbreak that has killed more than 550 people to be a national emergency, state media reports.
Health Minister David Parirenyatwa said hospitals were in urgent need of medicine, food and equipment and were suffering a critical staff shortage.
Zimbabwe is appealing for international help urgently to tackle the outbreak, which they had said was under control.
Meanwhile 16 soldiers have been held over disorder in Harare, say reports.
The Zimbabwean police told the state-owned Herald newspaper that 10 of the soldiers were detained over a looting spree on Monday which broke out after the central bank said it did not have the money to pay defence force members queuing for wages.
The other six were part of a group that reportedly looted shops and battled riot police last week.
Zimbabwe's defence minister has blamed the disturbances on an unruly minority in the army, and promised to punish the culprits.
Zimbabwe's deputy health minister told the BBC's World Today programme that patients would die without urgent medical aid.
Dr Edwin Muguti said the country's health sector was having "tremendous difficulties".
Health Minister Mr Parirenyatwa, meanwhile, told the Herald:
"Our central hospitals are literally not functioning."
The BBC's Peter Biles reports from neighbouring South Africa that as recently as last week, Zimbabwean officials had said there was no need to view cholera as an emergency.
The UN says at least 565 people have died from the cholera outbreak, which began in August, though correspondents say the real death toll could be much higher.
At least 12,545 cases of cholera have been recorded over the same period.
The outbreak comes as Zimbabwe is crippled by economic meltdown and political stalemate.
President Robert Mugabe's Zanu-PF party and the opposition Movement for Democratic Change have been rowing over a power-sharing deal following disputed polls this year.
Zimbabwe's prime minister-designate and opposition leader Morgan Tsvangirai is expected to meet Kenyan Prime Minister Raila Odinga in Nairobi on Thursday.
Mr Tsvangirai has been on a whirlwind tour of several African countries for talks on the Zimbabwe crisis.
On Wednesday, the European Commission said it would provide more than $12m (£8m) for drugs and clean water in Zimbabwe.
Most of Zimbabwe's capital has been without water since Sunday. State media said the water was cut because of a lack of purification tablets.
The health minister said there had been a drop in cholera cases in all provinces except Harare.
Medical workers tried to protest over the cholera outbreak
The World Health Organisation has said it is keen to help after Mr Parirenyatwa appealed for medical supplies and funds to pay hospital staff.
On Wednesday, riot police in the Zimbabwean capital, Harare, broke up a protest march by doctors and nurses angered at the worsening outbreak.
The authorities also prevented trade union members staging a protest over the country's banking meltdown.
The government has blamed its crisis on Western sanctions it says are aimed at trying to bring down Mr Mugabe.
But the sanctions imposed after allegations of electoral fraud and political violence are aimed at the president and his close associates and consist of travel bans and a freeze on their foreign assets.
Cases of cholera have been reported either side of Zimbabwe's borders with South Africa, Botswana and Mozambique.