Tea: Assam is internationally famous for tea. It has a large tea growing industry. Most plantations are located in the upper Assam. 70% of tea is exported outside India. People drink tea with/without milk and also sometimes containing ginger and spices such as cardamom.
Water: Problematic due to lack of sanitary facilities and sewage treatment. It is safest to assume water is unsafe for drinking without being chemically treated or boiled, which is one reason to stick to tea or bottled water.