older model, you will have to re-light your pilot light.
if you have an electric hot water heater, you will need to find your home’s electrical breaker box and turn off the switch that powers your hot water heater.
if you have a gas hot water heater, find the gas pipe leading to your thermostat and pilot light and turn the valve to the off position. if you decide to just turn your thermostat to “pilot” you won’t need to do this step.
turn off the cold water valve which is usually near the top of your hot water heater.
leave these on during the entire flushing process. this will help prevent a vacuum 