When leaving the Dimrill Dale (after their escape from Moria), the Fellowship comes across the spring which is the source of the Silverlode. Gimli says:
"Here is the spring from which the Silverlode rises," said Gimli. "Do not drink of it! It is icy cold."
That doesn't seem like a great reason not to drink the water. Icy cold water is great! Especially after several days in barren abandoned Moria. And even if it was below freezing somehow, it would eventually warm up (if they filled their containers).
Was there another reason that water should not be drunk?