The water heater size you will need can vary depending on your lifestyle and whether you get a tank or tankless water heater. A water heater that is too big or too small can affect your hot water quality and quantity, affecting the efficiency of the water heater. A water heater that’s too small will likely lead to a lack of hot water within a short amount of time, which can also overwork your water heater and potentially decrease its lifespan. However, a water heater that’s too big can cost you a lot in energy bills and waste a significant amount of unnecessary energy.
Whether your water heater is too big, and your energy bills cost more now than they should, or it is too small, and you run out of hot water way quicker than expected, you will want to get it replaced with an appropriate-sized water heater that meets the demands that you need it for.
What is the Capacity of a Water Heater Measured In?
Water heater capacity is measured by the gallon. The total load capacity calculates how much hot water can be used in an hour. However, your water heater’s capacity can change depending on the unit’s energy efficiency, the size of the water heater, and personal hot water usage amounts (e.g., showering).
Hot water heaters have an optimal energy point based on size and usage. A higher energy-efficient model may give you a higher hot water capacity than a less efficient, bigger-sized one will. However, your water usage can still impact the total load capacity.
Sizes for Tank Water Heaters
The sizes for tank water heaters will vary between 20 gallons all the way to 75 or 100 gallons for residential tanks, depending on what company you are purchasing from. Typically a 40-gallon water heater will suffice for a family of 4 with regular usage.
The size your family needs for a tank water heater is subject to your daily water usage and the efficiency level of the water heater you use. Some will be more efficient than others, so the greater your water heater’s efficiency level, the smaller the size needs to be.
Sizes for Tankless Water Heaters
The sizes for tankless water heaters change based on the hot water demand and the gallons per minute of the appliances that use hot water. This is why many people have issues with their tankless water heaters: they will get one that is not big enough for the high water output times they will use.
You can purchase the highest gallon-per-minute tankless water heaters, around 10 GPM, while the smallest is around 2 or 3 GPM. With this, you can get gas or electric tankless systems and decide what rooms and appliances will have access to hot water. You could also choose to get a couple of bigger tankless water heaters instead to service the entire house.
There are many factors to consider when looking into the sizes for tankless water heaters; determining this will take some time and help you have more consistent hot water for specific areas of your house and potentially save you space in your house too.
Sizes for Solar Water Heating System
The smallest solar water heater systems can be as small as 5 gallons but as big as over 100 gallons.
Like the tankless, these will take more initial figures and specific input for your situation than a tank water heater will need. How the solar water heater stores its water will take more time to heat the water than other water heaters.
It is also based on how much sun exposure your state and your house get, how efficient your system is, and how much hot water you want.
For example, the size of a solar water heater for a family of 4 can be anywhere from an 80-gallon to a 100-gallon system to ensure enough hot water for peak times due to how much sun is available each day.
Charts and averages are available to determine the different water heater sizes and which one you need based on your household. However, you will want to consult with your installer and data on how much hot water you consume daily to ensure these chart averages apply to your situation.
How Much Hot Water Do Daily Routines Take?
Most water you use throughout each day is used for daily routines such as dishes and showering.
If you want to use less hot water, some appliances allow you to control and adjust the temperature settings, but not all appliances can do this without costly upgrades. Knowing how much hot water your daily chores and habits consume will help you figure out the amount of hot water you need to choose the proper size water heater you need.
On average, Americans use 100-175 gallons a day per individual. This can fluctuate depending on your location and how much you use. Here is a rough estimate of how much water different chores and tasks will take:
Washing Machine Water Usage Average
This is based on how old your washing machine is. Using cold water for your washing machine will help save on energy bills and heating costs.
Typically, the machine you have can be searched to find the gpm if it is not stated on any labels.
Bathing Water Usage Average
This will depend on how full a bathtub you fill, but an average tub can hold anywhere from 15 – 30 gallons of water.
You can figure out how much you use by measuring the flow rate. To measure this, take a timer and an empty gallon jug, turn the water on and track how many seconds it takes to fill up the gallon. Then using that flow rate, you can estimate how much water you use in your bathtub by counting how long it takes to fill the tub and dividing that by the flow rate.
Showering Water usage Average
A shower can save hot water overall, but it can also consume more water, depending on how long a shower you take. The gallons per minute a shower will produce depends on the showerhead. Some can be as low as 1-1.5 GPM but the industry standard for new shower heads is 2.5 GPM. To get an idea for reference, a 10-minute shower will produce 10-25 gallons of hot water usage.
You can use the flow rate mentioned above to determine how much water you use in the shower.
Dishwasher Water Usage Average
Depending on the model and settings, a dishwasher will use about 4 – 10 gallons per use.
To determine how much water is used, you will have to check the model information in the manual or search it online if it is not labeled on the dishwasher.
Washing dishes by hand Water Usage Average
The amount of water used when washing dishes by hand will vary greatly. If you have an efficient dishwasher, it may be best to do a quick scrub to immediately ensure food is off of plates and leave the rest of the work up to the dishwasher.
The water usage can be as low as 2 gallons for more efficient models, but it could be 27 gallons. How hot water is used here causes a big difference in hot water costs.
Measuring how much hot water you use to wash dishes by hand will be trickier since you are likely to constantly change the water pressure by turning the water on and off or higher and lower.
At most, you will likely use 1.5 gallons per minute. However, this is also an easier way to adjust your hot water usage, as you have more control over how much water you use. Reducing your water pressure for easy-to-clean plates is one way to reduce your hot water usage.
Shaving Water Usage Average
Shaving tends to use the smallest amounts of hot water in your home if you shave in the sink. If you shave in the shower, you will consume more water because of the higher water pressure, and if you keep your water running while shaving. Where you shave and how much you shave can also affect how much water you use.
This can be as little as half a gallon of water used to as much as 10 gallons for shaving a face. For other areas, this could be more or less.
Washing hands Water Usage Average
This will consistently be one of your home’s lower hot water usage. On average, this will consume about 0.5 – 2 gallons of water daily, depending on how long you have the water on when washing your hands.
To reduce usage, try to use the water at a lower pressure or if you can turn it off while soaping up your hands.
Frequently Asked Questions
Is a 50-Gallon Water Heater Big Enough for a Family of 4?
In most cases, a 50-gallon water heater should be big enough for a family of 4. However, depending on your family’s water usage, you may want to install a larger tank.
With moderate use though, a 50-gallon water heater should work. It’ll also be easier and cheaper to install and be able to heat up quicker.
What Size of Tankless Water Heater Do I Need for a Family of 5?
For a family of 5, you will most likely need an 8-10 GPM tankless water heater for the entire house (and depending on how cold your geographical location is, maybe a second one). You could also use multiple smaller ones at the sources you want it for if you want smaller, more direct lines for hot water. Unlike a water heater tank, where you can estimate what size you need based on the number of people using the hot water, a tankless water heater takes more calculations to figure out. This can be a worthwhile investment if you want to have less energy loss from heating water.
Final Thoughts
The size of the water heater you need will change for almost every household’s needs. From the simplest and least time-consuming needs with a tank water heater to the more complex demands with a tankless or solar water heater, they all have their places where they shine and have their full potential.
Sometimes if you are not getting enough hot water from your current system, one or two simple changes in daily habits and hot water usage can make all the difference when it comes to reducing costs and conserving energy.
Try a few adjustments to your routines before spending money on a new system. If you need a new system, opt for more efficient brands. It will do you better in the long run.
