Can dehydration lead to constipation?

Yes: And other problems, best to avoid unless you live in the desert. :).

Constipation: Lack of adequate hydration may play a role in constipation as lack of fluid intake can cause the intestinal tract to absorb more fluid from stool, making it hard and dry. There are numerous other causes of constipation, some of which may be aided by dietary and lifestyle change. Others require medical treatment.

Yes: Yes if you tend to be constipated , drinking plenty of just plain water is helpful.