Fill a 4-quart glass container approximately 3/4-full with tap water.
Place the bowel of water into the center rack of your oven.
Set the oven temperature to 215-degrees F. Water boils at 212 degrees F but most ovens only allow for increments of 5 degrees.
Inspect the container of water once the oven warm-up light turns off. If the oven temperature is correct, the water will boil. If the oven temperature is too low, the water will not reach the boiling stage.