A snake requires food, shelter and water to survive, and drinks the condensation formed on its own back in places where water isn't readily available. Sea snakes find freshwater to drink in rainwater puddles on land and on the calm surface of the sea before it mixes with the saltwater.
Rattlesnakes in arid climates have impermeable scales and do not urinate to conserve body fluids. They use their senses of smell and taste to find water. Rattlesnakes and other desert-dwelling reptiles drink from puddles and also flatten their backs to collect rainwater to drink during the brief showers that do occur.