That's why the Australian Red Cross Blood Service wants people to make donating a regular habit and boost blood supplies over winter.

Corrimal resident Virginie Schmelitschek rolls up her sleeves to donate every fortnight and has recently reached the milestone of 400 donations.

"I started donating when I was 22 after having my first child," she said. "I'd been keen to volunteer but my options were limited with a small child, but my sister-in-law was donating blood and I thought that was one way I could help others.

"It's such an easy way to give and it's so necessary for so many people, for so many reasons."

Mrs Schmelitschek, now 65, only misses an appointment if she's sick or on holidays and has switched from whole blood donations to donating plasma. Plasma is a versatile part of the blood which can be used in many ways, from treating serious burns and cancer to protecting people with brain disorders or immune conditions.

"In the beginning I was donating blood every 12 weeks but changed to donating plasma as you can do that more often - once a fortnight," she said.

"It only takes me around an hour at a time, and it's very pleasant just sitting there and reading a book or having a chat while volunteers get you a drink and something to eat."

During National Blood Donor Week, Blood Service spokeswoman Nicky Breen called on other Illawarra residents to commit to regular donations.

Blood Service data shows of the 91,000 Australians who gave blood for the first time in the past 12 months, 43 per cent didn't return to make a second donation.

"Australia needs a new blood donor every five minutes," Ms Breen said.

"We need more people like Virginie to make blood or plasma donation a regular, life-saving habit.

"... It takes just an hour of your time to donate blood and every donation can help save up to three lives."

To donate call 13 14 95 or visit donateblood.com.au