Clear vomit is made up of saliva and water. The simplest explanation for this type of vomit is when your dog drinks too quickly or just drinks too much. However, there are some other possible causes of your dog's vomiting spells. Ponds and stagnant pools of water may be contaminated by bacteria and harmful blue-green algae that can cause your dog to vomit after drinking. Other symptoms that might arise include diarrhea, black stools, no appetite, weakness, muscle tremors, and respiratory distress. Some dogs will suffer from seizures and fall into a coma. Be sure to tell your vet if your dog shows any of these symptoms after drinking water.