The time it takes to boil water can vary depending on the size of the container, the heat source, and the amount of water. The time can also be affected by altitude, humidity, freshness of the water, and any minerals present in the water.
One cup of cold tap water will take about 1 minute to reach boiling at elevations close to sea level (~1g). At 5,000 feet (~0.5g) it will take twice as long. At 10,000 feet (~0.1g) it will take about 4 times as long.
The time for the water to reach boiling also depends on how full the container is, and can vary from a minute or less for a single cup of water up to 20 minutes or more for a full bathtub.
It’s possible to calculate the time it takes for water to boil by using two methods. The first method is estimating the volume of the pot and the second method is using a thermometer.
Pot Volume: Place your pot on a stove, turn it on medium-high, and fill it with enough cold water to reach within 1 inch of the top. Place a lid on top without sealing it fully. Place your hands around the pot (or use an oven mitten) and count how many minutes it takes for bubbles to rise back up to the surface. Multiply this number by 3 then subtract 10 minutes. This gives you an approximation of how long it will take the water to come to a rolling boil.
Thermometer: The thermometer method requires you to fill your pot with water and heat it over high heat. Once the water starts to boil, place a thermometer in the water (making sure it is not touching the bottom). Once the temperature reaches 100 degrees Celsius (or 212 degrees Fahrenheit), remove the pot from heat. This method is more accurate than the pot volume method because it takes heat loss into account.
The thermometer will continue to rise even after you remove the pot from the stove due to residual heat. After 5 minutes, check your reading and estimate how long it will take for the temperature to reach 212 degrees Fahrenheit. This estimate is how long you should wait until the water has come to a rolling boil.
So this is how long does it take to Boil Water.