How much a dog drinks varies with food, activity, temperature and the individual, among other things. What matters most is a clear change from your dog's normal pattern. Increased thirst and urination can occur with kidney disease, diabetes, hormonal diseases, pyometra and several other conditions.
Try to get an idea of when the change started and whether your dog is also peeing more, losing weight, becoming tired or changing its appetite. Do not restrict access to water on your own, as this can be dangerous if the body actually needs to get rid of larger amounts of urine. The vet usually starts with blood and urine tests to sort between the most common causes.
Book an examination if your dog has clearly been drinking more than before for several days, or if the increase is large. Seek help sooner if your dog is also unwell, vomits, becomes very tired or if an unspayed female dog has recently been in season.