Hello and welcome to ask a doctor service. I reviewed your query and here is my answer. Plastic tube is placed in ear in a condition called otitis media with effusion. Yes it has got some precautions like you shouldn t swim with it and even you have to cover your ear canal when taking bath as this tube forms a communication between external and middle ear. If water goes into ear, it will directly goes into your middle ear which can cause some serious infection and even can effect your tube. Hope i answered your question. Feel free to ask if you need any help. Thanks.