Language - French is the official language, but the flavor spoken by local folk is a curious Norman dialect. 

Electricity - Voltage is 220 AC, 60 cycles. American-made appliances often require French plug converters and transformers.

Water - As there are no rivers or fresh water sources in St. Barths, rainwater collected in cisterns comes in very handy during periods of drought. In addition, the island has an active facility to desalinate ocean water, and provide city water to most homes, but is very expensive. This means that water remains a precious resource and should be used intelligently, in moderation, without thoughtless waste.