Why Does My Hot Water Run Out So Quickly?

A cold shower is no one’s idea of a good start to the morning! If you and your family members are noticing you are running out of hot water faster than before, it could be your water heater’s cry for attention. So, before you blame your spouse for the cold shower, understand that a hot water heater unable to keep up with demand is a red flag pointing to the need for repair. There’s no reason to continue to suffer through icy showers day after day. Some simple troubleshooting tips can help you to identify the source of the problem.

Why Does My Hot Water Run Out So Quickly?

Water Heater Tank Sizes

Make sure your tank size is adequate for the job. Tanks are rated at how many litres per hour they heat. A peak rating of 150 means 150 litres of water are heated for use in an hour’s time. Each appliance uses a certain amount of hot water to do the job. For example, an average shower requires 80 litres of hot water; a dishwasher, about 6 litres; and a clothes washer, about 7 litres of hot water per hour. In a scenario where two loads of wash are done, two showers are taken and a load of dishes is finished, a hot water tank that supplies a peak-rated 40 litres of hot water per hour will ensure that you won’t run out of hot water in the shower. In this same scenario, if you have a 30-litre peak hot water heater, your shower won’t remain hot for very long.

Sediment Build-up

In a tank water heater, the water can only take up as much space as the tank will allow. Water is not the only thing in the tank. In places with hard water, minerals accumulate in the tank. If you do not clean it out regularly, the sediment builds up in the tank and leaves less room for water. Over several years, the build-up could take several litres of space, leaving you cold when you want to be warm. At the very least, you should request maintenance services from your plumber, to clear the sediment from your water heater and plumbing. You may also want to install a home water softener, to prevent the problem of build-up in the first place.

Tankless Water Heaters

In most cases, a tankless on-demand water heater fails to supply enough hot water if the unit is too small. Electric on-demand water heaters are generally only satisfactory for one or two people. Gas-fired on-demand water heaters are more versatile, but if everyone in the household is using hot water at the same time, it won’t be able to heat up water rapidly enough to keep your shower warm. Many factors determine whether a tankless hot water heater will run cooler, and some of these include the incoming groundwater temperature and the flow rate at a specific temperature.

Inefficient Water Heater Use

No hot water heater is going to be perfect, always accommodating all of your needs. If you want to know that the hot water will be available to you, you must also tailor your use of the hot water to a reasonable level. There are many reasons to conserve water, but several of them are also related to your own convenience. Wait to wash clothes or run the dishwasher until you have a full load. Create a schedule to use those appliances at times when you are not planning to do a lot of cooking or take a long bath or shower. With a little forward thinking, you can minimize a lot of hassle.

Hot Water Overuse


If there are multiple appliances using hot water when you are taking a shower, you will run out of hot water. Dishwashers, washing machines and even hand washing at the sink use enough hot water to make your shower quickly run out of hot water. Schedule your showers during times when there is no other appliance using hot water. If you still run out of hot water, there may be a larger problem.

Worn or Broken Equipment

Failing to arrange for regular service can lead to more than just hard water deposits in your water heater. It can also lead to broken equipment inside your water heater. For example, if your dip tube is broken, you may notice a difference in the temperature of your water. The dip tube pulls the incoming cold water to the bottom, directly to the heating element. That ensures that the water heats up faster. A broken dip tube doesn’t direct the water anywhere, just mixes cold and hot water. Be sure to schedule maintenance at least once a year to confirm that everything in your hot water heater is working properly.

Great Tips to Improve Usage

Below are some of the great tips to help you keep the hot water running when the water heater can’t keep up.

  1. Limit Your Usage. An average shower dispenses 40 litres of water every 60 seconds. If the capacity of your water heater tank is 150 litres, you can run out of hot water at any time. A water heater tank with a 70-litre capacity won’t deliver more than 43 litres of hot water. The reason is that the hot water gets diluted when the cold water gets into the tank. With this in mind, you can only use part of your hot water and not all of it.
  2. Know the Recovery Time. When your water heater gets drained, it’ll need some recovery time to dispense hot water as it once did. It usually takes minutes or hours to recover (depending on your tank size). For instance, a 70-litre tank will take about 26 minutes to refill and heat the water. To have hot water in the fastest way possible, avoid using hot water when the recovery process is not done. Allowing the recovering time to complete will make the unit heat the water quicker. Drawing water when the recovery process is still going on will add cool water to the tank. When this happens, the recovery time increases, and the water will not be well heated.
  3. Loose Connections Electric. water will stop functioning properly if the wiring of the unit becomes loose. Hence, turn off the unit and check if the entire wiring is still in place. This problem is rare to encounter, but you should also consider it.

Call Service Today

If you’ve tried some simple fixes and still aren’t getting hot water, we recommend calling a plumber to take a look. Service Today has served Sydney, Adelaide and Melbourne communities for 20 years and is one of the most trusted names in the business. Our plumbers can flush your tank, repair or replace your heating unit to restore your hot showers and your relaxation time. Contact us today to schedule a consultation.