People with compromised immunity, the young and the elderly have been badly affected by the gastric illness that has swept through Havelock North.
Thousands of people in the Hawke's Bay town have fallen sick after the water supply was infected with campylobacter bacteria. The cause of the contamination is not yet known.
A "boil water" notice is still in place until secondary sources of infection can be ruled out, with residents advised to boil all water for at least three minutes.
All schools, and some kindergartens and businesses, have temporarily shut their doors.
Kirsty Webb, a mother of two who has been living with cancer for several years, said she had to drink lots of water as part of her cancer treatment - and that has had terrible consequences.
"I've just come back from the accident and emergency department... Tomorrow at 2.15pm I had my 28-day cycle cancer treatment and I can't have it now," she said.
"If I become more unwell than I am right now, I have to start the antibiotics... but the antibiotics lower your liver function further, so it's kind of a catch-22."
Ms Webb said she was angry that she and her children had been exposed to the bacteria.
"The kids had a sports day on Friday at school and it was a warm day, and they were drinking lots and lots of water."
Deborah Berlin said her entire family - her, her husband, their five year-old daughter and their three-year-old son - had all been sick.
The family's 12-week-old baby was now spewing too, she said.
"I literally could not lift my body off the bed… feeling so lethargic that you can't get out of bed, you've got nothing left in your cells in your body because you're so depleted."
Her husband was a "shadow of himself" and had been going to the bathroom every 10-15 minutes for three days. They'd been up all night, every night, she said.
"I feel like they have poisoned me and my family and I feel disgusted and betrayed.
"My daughter's been on the toilet rocking back and forth and just crying, and there's nothing you can do for her."
The illness had caused pains that she described as similar to those of childbirth.
"Really, really horrible cramps that you can go [the] toilet and five seconds later feel a little bit of relief, then you're straight back on there again."
Havelock North Business Association committee member Adrienne Pierce said businesses were struggling with sick staff or children of staff and with a lack of customers.
People were also cancelling bookings at motels, she said.
"It's the biggest event of this kind in the country ever, so you can understand why people are fearful."
Pipi Cafe & Food Truck owner Chris Morris, who employed 25 to 30 staff, said business tailed off at the weekend, forcing him to close the shop today.
Mr Morris said he also had a big order cancelled due to the client's ill health.
"It's a bit of a perfect storm, really. It's our quiet time of year, cashflow's down. We talk about people having sick days; I feel the pressure of having to generate that income to pay that sick day.
"We'll take a huge hit out of this and we could only be at just the start of it."
Mr Morris said he hoped to be able to open again by the weekend.