The demand for blood has surged over the last five years as the population ages and grows.
Figures from the Health Sciences Authority (HSA) show that 108,100 units of blood were used for medical transfusions last year, up a quarter from 86,300 in 2009.
An ageing population requires more blood as the elderly are more likely to develop age-related medical diseases such as cancer, which can cause anaemia, a condition where one lacks healthy red blood cells, said HSA.
"Unlike younger patients, the elderly often have a lower tolerance for anaemia due to conditions such as cardiovascular diseases and, thus, are more likely to need blood transfusions to prevent complications," said an HSA spokesman.
As people age, they also tend to need more operations which require input of blood.
By 2030, the number of elderly people here will triple to more than 900,000. Nearly half, or 14,511, of the 32,000 patients who received blood last year were aged 65 and above. The number of seniors who had blood transfusion grew 18 per cent from 12,310 in 2009. Blood use is projected to go up by 3 to 5 per cent annually, though there was a 7 per cent jump last year.
To meet transfusion needs and emergencies, blood stocks are usually kept at a level enough for six days' usage. However, the reserves can dip during the holidays when donors are away.
Singapore Red Cross secretary-general Benjamin William said an ageing population not only means demand has risen, but it also means the supply of blood may drop.
"The donor pool may shrink as regular blood donors can no longer donate if ill health strikes when they get older," said Mr William.
"We know this silver tsunami is coming, so we can prepare for it, or wait and hope it doesn't hit us, which would be complacency."
About 70,000 people donate blood every year, of which about 1 per cent are aged above 60.
There is no data on the number of elderly blood donors who stop donating for health reasons.
But one such donor is retiree James Law, who donated blood for 40 years until four years ago.
"The doctor found a certain protein in my blood, which is indicative of cancer if present in large quantity, so it was deemed unsuitable for transfusions," said the 67-year-old who still volunteers at a blood bank.
The Singapore Red Cross is trying to get more young people to donate blood. It is in talks with the Ministry of Education to include blood donation information in the curriculum for tertiary students. It also hopes to get schools to take ownership of the blood donation centres in their area by having their students volunteer there.
Last year, it launched the Red Cross Connection app, which gives the young a platform to broadcast the number of lives they have saved by donating blood, and hopefully encourage their friends to do the same.
The aim is for youth to make up 35 per cent of the donor pool, up from 31 per cent last year.
Ms Elizabeth Sarojinidevi, 61, hopes more young people will donate blood. She had a medical emergency two months ago when her blood pressure plunged as a worn-out liver led to internal bleeding in the stomach. Her siblings could not donate blood due to old age or medical conditions.
"They gave me three pints of blood from the blood bank and that's why I am alive today," said the school counsellor. "I am grateful to live in a country where blood is available readily because people have come forward to donate, and hopefully the young will continue to do so."