Most of the region's emergency services have teamed up to give blood, and they're asking everyone else to do the same.
The annual Sirens for Life campaign kicked off Friday, with members of Waterloo Regional Police Service, Regional Paramedics, Waterloo Fire and Rescue and other agencies rolling up their sleeves.
WRPS Chief, Bryan Larkin says the need for blood never takes a summer holiday.
"The reality is, is that our hospitals and our health care professionals do need blood...We're encouraging people to give a pint, rather than have a pint and actually make a difference in our community. Larkin told 570 NEWS.
Even a routine car crash can result in a victim needing 50 units of blood.