Updated: February 22, 2021 by Lonnie Thomas

How Long Does it Take For a Water Heater to Heat Up?

The only time we think about our hot water heater is when it isn’t giving us hot water.  Even then, all we want is for it to be fixed or replaced so we can take a shower, and we don’t think of anything else.

But, there is more to think about than just taking that hot shower.  How big a tank should you have?  What kind of tank should you have, gas or electric?  What about a tankless heater?  How long a shower should you take?

Let’s see if we can help.

Types of Hot Water Heaters

Water heaters can be powered by gas or by electricity.  Each will heat your water to the desired temperature, and each will have a temperature control dial or panel you can use to set that temperature. 

An alternative is the tankless water heater, also called instantaneous or on-demand water heater, which, as the name suggests, has no tank. In a tankless system, the water circulates through a coil system and heats the water. Tankless heaters are rated by the gallons per minute with an average life span is 20 to 25 years.

Each type of tank is distinguished by, among other factors, the time it takes to heat and deliver hot water to your shower or faucet:

  • The average gas water heater takes between 30 and 40 minutes to fully heat up the water in its tank, depending on the tank size.
  • The average electric water heater takes about twice as long as the average gas heater to fully heat the water in its tank or between an hour and an hour and 20 minutes to heat up.
  • As mentioned, tankless heaters heat water instantaneously when hot water is called for in your shower or faucet.

Gas water heaters and electric water heaters will require some space in your house, usually the basement.  They are mostly silent and run only enough to keep the water in the tank to the set temperature.  When the water in the tank has been used, it must refill and heat a new gallonage, so there will be a gap when water is being heated.  The water heater recovery time will be the same as noted above to heat a full tank.

Tankless water heaters don’t take up much space and heat only on demand.  Because they heat upon demand, the hot water supply is steady until need ends and can help reduce energy costs for your home.

Conversely, tankless water heaters are typically more expensive than gas or electric water counterparts.  In older homes, they may require an upgrade in the electrical system, and larger homes may require more than one unit.

Approximate Heating Time

TANK SIZE (GALLONS)GASELECTRIC
3030 Minutes60 Minutes
4035 Minutes70 Minutes
5040 Minutes80 Minutes
6050 Minutes100 Minutes
7055 Minutes110 Minutes
8060 Minutes120 Minutes
9070 Minutes140 Minutes

How Big Should Your Hot Water Tank Be?

The household size will determine the size of the hot water tank you will need.  A loose estimate of tank size for your home should follow these guidelines:

  • For one to two people, a tank of 30 – 40 gallons should be sufficient.
  • For two to three, a tank of 40 – 50 gallons should fulfill needs.
  • For three to four, go up to a 50 – 60 gallon tank.
  • For five and up, 60 – 80 gallon tanks should be installed.

The www.energy.gov website suggests a small tank (up to 50 gallons) is usually sufficient for up to three people; a medium tank (up to 80 gallons) works well for 3 – 4 people, and a large tank (80 – 90 gallons) will be needed for 4 – 6 people.

With a tankless water heater, the expected gallonage use will determine both the size and the number of units your home will require.  That is a subject for another article, though.

How Do You Know If Your Hot Water Heater is Working?

The obvious answer to this question is “when you get hot water when you turn it on.”  But, to be serious, it’s easier to answer the question, “How can you tell your hot water heater is not working?”

There are some signs to notice:

  • Not enough hot water
  • The water temperature varies often
  • Your tank is leaking
  • Water flow is reduced
  • Noises you aren’t used to hearing
  • Smelly or discolored water
  • Your tank is old

Any of these signs are enough to consult with a plumber for an inspection.  Don’t wait, thinking it will just go away.  Be proactive and get an answer.  There’s nothing worse than going into the shower to get ready for work and being surprised by cold water.

Why Does My Water Heater Take So Long To Heat Up?

There are several reasons why it might take a while for your water to heat up at the shower end.  They include its distance from the hot water tank, the pipe diameter, and water flow rate. 

The longer the water has to travel, the longer it will take for the hot water to reach your end.  The wider the pipes, the more water per inch is required to flow, and thus, the longer it takes to reach you.  The longer the distance and wider the pipe, the more cold water has to flow out before the hot water reaches you.

And, remember, patience is a virtue.  Assuming the water heater is in good working order, the hot water will eventually arrive.

How Long a Shower Should You Take?

Shower

Separate and apart from the issue of water conservation, there are hygienic reasons for keeping your showers in the 5 – 10 minute range.  Many dermatologists recommend this range in the best interest of your skin.  It’s long enough to cleanse and hydrate your skin without overdoing it.

In Closing

Gas, electric and tankless will determine how long it takes for your water to heat.  Each will do the job well.  Other plumbing factors will determine how long it will take for the hot water to reach you when you call for it. 

The tank size will determine how quickly you will run out of hot water if you shower too long.  The purpose of this piece is simply to identify all of the interrelated factors that affect the hot water supply in your home.