Dependency

Dependency is a feature that only exists in The Sims Castaway Stories. There are two types of dependencies: If a Sim buys an object that needs water (plumbing) to work (toilets, showers, sinks, bathtubs etc.), he or she needs to buy a water tower from either the buy mode or the story reward section. If a Sim buys an object that needs electricity to work (electric ovens, radios, etc.), he or she needs to buy the windmill with an electric generator, only buyeable if you get it in Story Mode.
 * Plumbing
 * Electricity

Trivia

 * If it hasn't been raining for days the water tower will get empty and you will need to wait for rain to able to use a "plumbing" object.
 * Objects that depend on plumbing will have a blue background in buy mode while objects that depend on electricity will have a yellow background.
 * Almost every pre-made residential lot in the game has a water tower near the house.