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Why Is My Water Heater Running Out of Hot Water Faster Than Normal?

Wondering why your home’s hot water supply is running out faster than it used to? Well, first, answer this question: Did the change happen gradually or all at once?

You see, if the change was gradual, the issue is most likely sediment buildup inside the water heater tank.

But if the change was sudden, the issue is either:

  • A bad lower element
  • A broken dip tube

We’ll explain these problems below and what you can do to get your long, hot showers back for good.

Need a plumber to diagnose and fix the issue stat? Just contact us. We’ll send one right over.

If the change was gradual…

...you likely have sediment buildup in your water heater tank.

So what is “sediment buildup”? Well, it’s basically a thick layer of dissolved minerals that settle to the bottom of your tank.

You see, even if your home has a water softener, the water coming into the water heater has a small amount of dissolved minerals (such as calcium and magnesium). And over time, because the minerals are heavier than water, they settle to the bottom of the tank, creating sediment buildup.

Now, a little bit of sediment is normal and won’t affect your hot water supply. However, if you don’t keep your water heater maintained, that layer of sediment builds and displaces hot water, decreasing the amount of hot water available for use.

Think about it: If you have a 40-gallon water heater with 10 gallons of sediment buildup in the tank, you now have a 30-gallon water heater.

Signs you have sediment buildup:

TPR valve and discharge pipe

If the TPR valve starts hissing or the discharge pipe starts leaking water, you might have sediment buildup in your water heater tank.

What to do:
Have a plumber flush your water heater
. This means they will drain the tank, clean out the sediment, inspect and maintain other elements and refill the tank.

If the change was sudden…

...you likely either have a:

  • Bad lower element
  • Broken dip tube

Let’s take a closer look at both of these problems:

A bad lower element

Electric water heaters have two elements that heat the water; one at the bottom of the tank and one at the top.

The lower element basically handles the brunt of the work. Cold water is pushed to the bottom of the tank to be heated by the lower element. Then, as the heated water naturally rises to the top, the upper element only comes on periodically to keep the water at a consistent temperature.

So, if that lower element suddenly goes bad, you’ll immediately notice a severe decrease in the amount of hot water that’s available to you.

Reasons the lower element might go bad include:

  • Sediment buildup is burying the element, causing it to overheat
  • The thermostat controlling the element has gone bad
  • A short in the element wiring

What to do:
Have a plumber inspect the water heater
to confirm that the element is bad. They can repair or replace the element.

A broken dip tube

Every water heater has a “dip tube” that’s responsible for pushing the incoming cold water down to the bottom of the tank to be heated.

dip tube

After that cold water is heated, it rises to the top of the tank where it can be pulled out whenever you need hot water somewhere in the house.

But if that dip tube breaks or falls off, incoming cold water no longer gets pushed to the bottom of the tank. Instead, it mingles with the already heated water at the top of the tank, lowering the temperature of the water that is delivered to you. And the more cold water that enters the tank, the sooner you run out of hot water altogether.

Reasons a dip tube can go bad include:

  • Normal wear and tear. Some dip tubes are made of plastic that have a shorter lifespan than others.
  • It’s defective. A lot of water heater manufacturers sold water heaters with defective dip tubes from 1993–1997. These dip tubes were prone to cracking and breaking apart long before they should have.

Need more information about a broken dip tube? Just read our blog, “My Hot Water Turns Cold After a Few Minutes”.

What to do:
Have a plumber inspect the water heater
to confirm that this is the problem. If it is, they’ll replace the dip tube.

Need help from a MN plumber?

We’re here to help. Just contact us and we’ll send over a qualified and trusted plumber in no time.