What should be done before flushing a domestic hot water storage tank?

Before flushing, a nearby hot water faucet should be opened to allow air into the system and prevent vacuum lock. In some cases, the temperature and pressure (T&P) relief valve may be opened briefly for venting, but only with caution—scale buildup can prevent it from reseating fully. Once vented, standard blowdown steps can be followed to safely remove sediment.