Cold water can shock the vocal cords and create tension which limits your vocal range and ability. But, hot water can cause inflammation and increase mucus production. Stick to room-temperature water which enables flexibility in your cords. Water can have a significant impact on the sound of a person's voice. While it is often thought that cold water makes a person's voice sound deeper, this is not always the case. In fact, it is often the opposite.
When a person takes a cold shower, their body cools the water that runs through their vocal cords. This causes the vocal cords to stretch and produce a deeper sound. However, this effect is fleeting and will eventually wear off. In fact, many people find that their voice becomes deeper when they take warm showers. The warm water loosens the mucous that has built up on the vocal cords and allows them to vibrate more freely.