Yah you can start complementary feeding at 6 months. Start with semisolid food like Dal, mashed potato with ghee and sugar or little salt, multigrain halwa, suji halwa( but semisolid consistency). Fruits like banana can be given but if you want to give apple then you will have to boil it before giving. Yah water is to be given when you start complementary feeds. Continue breastfeeding. Apart from breast milk other milk is not required. But if you want to give then you can give lactogen/ nan pro stage 2 ( which is for babies from 6-12 months)