Why doesn’t my baby drink water?

Dear doctor; I started my seven-month-old son on solids a couple of months ago. He loves eating food and wants to eat everything that I provide. However, he now refuses to drink anything at all from a bottle or toddler cup. Luckily, he still drinks from the breast a few times a day, but I’m worried that this isn’t enough. How should I help him get into drinking fluids?