This is anecdotal but one of their students once told me that Waterloo puts more emphasis on mathematics compared to other universities. It's not that students there necessarily take more math courses but that most courses try to integrate math and teach the mathematical aspects of their material, even courses outside of science. Their wikipedia page states that "Waterloo created the first Faculty of Mathematics in North America" so I guess it's a tradition for them.
Waterloo does have a strong Math tradition. But further to that, for a long time the Computer Science degree at Waterloo was a specialization under their Bachelor of Mathematics degree. So you had to fulfill all of the requirements of the Math program and graduated with a "BMath". You were also offered interesting minors like "Combinatorics and Optimization" where you would get deep into Cryptography, Graph Theory and so on.
I can't say how it compares to other schools, but certainly many of my memories of CS at Waterloo were working feverishly through difficult math assignments so I could get back to the lab. ;)
I went to Waterloo as a Psychology major and I would say that is true. That mathematical attitude does seep into a lot of of the culture and programs. Talking to other psychology grads, the program at Waterloo had significantly more emphasis on stats and analysis.
