Hamilton's blood bank reserves are critically low.
The New Zealand Blood Service is calling for more volunteers to donate blood and plasma to bolster critically low levels of blood reserves in its Hamilton blood bank.
Team leader recruitment Dean Hill said the organisation was very short of donors and a recruitment drive is underway.
"We need more donors and we need them now.
"We have about 4000 active donors in Hamilton city. We really need to double that."
Mr Hill said while demand for blood and blood products had reduced over the years, it was a struggle to keep up with demand because donor numbers had dropped off.
He said "controlled demand" - that is use of prematched blood for surgeries where haemorrhage is a risk - had dropped somewhat. "There is less waste in that area than there used to be."
But the NZ Blood Service struggles to achieve the required number of donations each week, particularly at a time of year when colds and flu are prevalent, which mean prevent people from donating.
Mr Hill estimates that the Waikato regional blood service needs 700 appointments each week to ensure they collect the required 535 whole units of blood. Of that 700, some people won't be able to donate because of illness and may be temporarily or permanently deferred from donating.
One of the key demographic groups that the blood service is missing out on donations from is young, solidly built men. They also need many more Maori and Pacific Island donors.
"Even if we could increase our active donors by 50 per cent... that would be great. I know people are often at odds as to what charity to donate to. Donating blood costs nothing and you can help save lives.
"We are priviledged to have many committed donors. In fact, just last week one regular donor even caught a flight back to Hamilton especially to make his appointment on time. That really is going above and beyond."
Mr Hill said a blood donation appointment takes about 45 minutes and includes completing a form, an interview with a nurse, the actual donation which takes about 4-10 minutes, and then a short rest with a cup of tea and a biscuit.
People can donate whole blood every three months, plasma donors can donate monthly.
Donations of plasma, which is used to create medical products including those for cancer patients, takes a little longer.
The donor is hooked up to a machine which extracts the plasma from the blood and returns the rest of the blood to the donor.
Mr Hill said the blood service really needs donations of O+ and A+ - those blood types are the two most common and make up about 70 per cent of the population's blood types.
They also need O-. While people whose blood type is O- account for about about seven per cent of the population, that blood type is universal in that it can be administered to anyone of any blood type.
"It's what the rescue helicopter takes with them because in an emergency situation you don't have time to establish what blood type someone is," said Mr Hill.
Blood donations in the Waikato are fairly equally split across five sectors: prematched donations for surgeries, cancer patients, newborns and/or their mothers, accident victims, and burns victims.
For information on how to donate visit www.nzblood.co.nz.