Bottled water is widely available in Tofo, there is a clean source of local drinking water.
You can buy your own beer from the shops on the road to Inhambane if you want to save a little money. When buying beer try to get cans rather than bottles, most bars and taverns will ask you not to take bottles away or you can pay a deposit on it. These deposits are hard to get back as vendors seldom have money to pay you or just aren't willing and will coax you into accepting a trade.
Going to taverns on the outskirts of town on Sunday afternoons are worthwhile to get away from the more popular tourist spots. You'll find friendly locals willing to share a drink and a few laughs.
Local rums and gins are inexpensive but you'll need some courage. Tipo Tinto is a good local rum!
Fatima's Nest
Every night party place, where you can enjoy different kinds of drinking games with the staff.
Dino's Bar and Restaurant
Although probably the least authentic this is one of the more popular spots to go for a decent meal or drinks.