Hot Water Running Out: Causes and Solutions Explained

In the past, you may have revelled in a seemingly endless supply of hot water. you might now be facing the frustration of cold showers or a tepid trickle for the last person to bathe. If you’re noticing that your access to hot water is dwindling more quickly than before, it’s a sign that something is not quite right. This situation could stem from changes in how your household uses water, issues within the hot water system itself, or even the energy source powering it.

This comprehensive guide explores seven common reasons for hot water shortages in Queensland homes. it offers insights into how long you should expect to wait for hot water to return after it has been depleted, along with practical checks you can perform before calling a plumber.

Key Factors Contributing to Hot Water Shortages

• An electric tank operating on an off-peak (controlled load) tariff only heats water when the electricity network activates its supply, which may leave it cold until the next designated off-peak cycle.
• If the water remains cold the following morning, it suggests a malfunction rather than just high demand.
• Typical causes for hot water shortages include an inadequately sized tank for the household’s needs, a malfunctioning heating element or thermostat, sediment accumulation, thermostat settings that are too low, insufficient solar boosting, tariff limitations, or an aging system.

How Long Should You Wait for Hot Water to Return After Depletion?

The waiting time for hot water to return significantly depends on the type of hot water system you possess and its energy source.

• Electric storage tank on a standard tariff: the heating element activates as soon as the water temperature drops, allowing for rapid reheating of the tank. Larger tanks with smaller heating elements may take longer to reach the desired temperature.
• Electric storage tank on an off-peak tariff: in Queensland, these tariffs are known as Tariff 31 or Tariff 33. Your electricity provider dictates when power is supplied, meaning a tank that empties in the evening may not begin reheating until the next off-peak cycle.
• Gas storage tank: the burner ignites as soon as the water temperature decreases, enabling immediate reheating of the tank. If it fails to do so, check the pilot light for any issues.
• Gas continuous flow: these systems heat water on demand, eliminating the risk of running out. If the water turns cold, the problem likely lies with a fault, gas supply, or flow issue rather than a depletion of stored hot water.
• Solar hot water: recovery is dependent on sunlight availability and booster efficiency. During several overcast days, the booster typically assumes the majority of the workload.

According to Energy Made Easy, the Australian Government’s energy comparison service, a controlled load tariff applies to larger appliances like hot water systems operating on their own circuit, with power restricted to specific time slots, typically overnight and on weekends (Energy Made Easy, Understanding controlled loads). If your hot water remains cold the next morning after an off-peak period, it indicates that the tank has not reheated, suggesting a fault rather than excessive consumption.

For those using gas hot water systems facing shortages, our guide on pilot light issues can assist you in performing the necessary preliminary checks.

1. Is Your Hot Water System Adequately Sized for Your Household?

Hot water systems are generally sized to meet the demands of the households they serve. As families grow, with teenagers taking longer showers and more remote work leading to increased daytime usage, a system designed for two individuals may struggle to fulfil the needs of a family of four.

Indications that your hot water system may be undersized include:

• Hot water runs out after just one or two consecutive showers.
• The family must meticulously coordinate shower timings to prevent the last person from having a cold shower.
• The issue arose following an increase in household size rather than due to the system aging.

If your hot water system is operating correctly but simply lacks the necessary capacity, upgrading to a larger tank or a different type of system will solve the problem. Our guide comparing various hot water systems suitable for Brisbane and Moreton Bay homes covers options such as electric, gas, solar, and heat pump systems.

2. Are There Issues with the Heating Element or Thermostat in Your Electric Hot Water System?

An electric storage tank relies on its heating element to warm the water, while the thermostat regulates the heating cycle. If either component begins to fail, the water may not heat adequately or at all, causing the tank to deplete more quickly than it should.

Signs of a failing heating element or thermostat include:

• The water is warm but does not reach the desired hot temperature.
• Hot water runs out noticeably sooner than it did a few months ago.
• The safety switch trips when the hot water system is turned on.

Both the heating element and thermostat are located behind a cover on the tank and operate on mains power. Avoid attempting to open this cover yourself. A qualified plumber can evaluate both components and determine whether replacement is a viable option based on the tank’s age. Schedule a hot water system inspection if you notice any of these symptoms.

3. Has Sediment Accumulated in Your Hot Water Tank?

Over time, minerals in the water settle at the bottom of a storage tank. This sediment layer occupies space that should be filled with hot water, and in electric tanks, it can coat the heating element, obstructing the heating process.

Indicators of sediment build-up in the hot water tank include:

• Rumbling or popping sounds coming from the tank during heating.
• Hot water depletes more quickly despite no changes in consumption patterns.
• Cloudy, gritty, or rusty water emerging from the taps.

During a service visit, a plumber will flush the sediment from the tank and inspect the sacrificial anode, a rod designed to corrode and protect the tank from deterioration. Our article on hard water and hot water systems in Caboolture discusses how water quality impacts a tank’s longevity.

4. Is Your Hot Water Thermostat Set to an Inadequate Temperature?

Some individuals lower the thermostat setting to conserve energy or to avoid excessively hot water at the taps. The downside is that cooler water in the tank depletes more quickly, as less cold water mixes during showers, leading to greater consumption of the tank’s contents.

The Queensland Government recommends that stored hot water in homes be heated to a minimum of 60°C to inhibit the growth of bacteria such as Legionella. New and replacement systems must include a temperature control device to ensure water reaches taps at no more than 50°C (Business Queensland, Hot water systems). Lowering the thermostat below 60°C to prevent scalding is not advisable, as the temperature control device is specifically designed for this purpose.

An improperly adjusted temperature control device can also lead to showers feeling cooler than expected. A licensed plumber can assess both the tank thermostat and tempering valve to ensure they are calibrated in accordance with Queensland regulations.

5. Is Your Solar Hot Water System Receiving Sufficient Sunlight or Is the Booster Malfunctioning?

If you own a solar hot water system and notice a decline in performance, this is often linked to weather conditions or the functionality of the booster. The system relies on its electric or gas booster during cloudy or rainy days, as well as in winter when sunlight is less intense.

Key signs indicating issues with a solar hot water system include:

• The shortage coincides with a period of overcast or rainy weather.
• The booster switch is turned off, or the booster fails to activate as intended.
• The controller displays a fault indicator or error message.

Our guide to solar hot water boosters in Queensland explains how the booster operates and clarifies why every solar system requires one.

6. Are Tariff Restrictions Impacting Your Electric Hot Water System’s Reheating Schedule?

Many households in Queensland use electric hot water systems on Tariff 31 or Tariff 33. These tariffs provide reduced rates because the network only powers the hot water circuit during specific times. If your household consumes more hot water than the tank can replenish between these intervals, it will run out and remain cold until power is restored.

Signs that tariff restrictions may be the issue include:

• Hot water runs short in the evening but is available again the following morning.
• Your electricity bill includes a separate entry for a controlled load, specifically Tariff 31 or Tariff 33.
• Extra guests or additional laundry loads have pushed the tank to its limits.

Energy Matters notes that the second controlled load option is slightly more expensive than the first but provides power for a longer duration, often covering part of the day (Energy Matters, Controlled Load Tariff Explained). Your options include upgrading to a larger tank, switching to a tariff with extended supply hours, or selecting a different type of system. Your electricity retailer can confirm your current tariff.

7. Is Your Hot Water System Approaching Its Lifespan Limit?

As hot water storage tanks age, they often lose capacity due to sediment build-up and wear on components. If your hot water supply is dwindling and the tank shows signs of rust, leaks around the base, or increasing noise levels each year, replacing the system may be more practical than continually repairing it.

Our article on the lifespan of hot water systems provides a detailed overview of the typical duration for each type, while our guide on leaks from the bottom of a water heater clarifies what a leak around the tank’s base generally indicates.

Crucial Checks Prior to Contacting a Plumber About Hot Water Shortages

A few straightforward checks can help pinpoint the cause of hot water shortages and assist your plumber in diagnosing the issue. None of these steps require you to open the hot water system.

• Monitor when the hot water runs out: Is it only in the evening, after a specific number of showers, or is it a constant issue?
• Examine your electricity bill for any mention of a controlled load, Tariff 31, or Tariff 33.
• Inspect the base of the tank and the relief valve pipe for any signs of dripping or pooling water.
• Listen for any rumbling or popping sounds while the tank heats.
• If you have a solar system, ensure that the booster switch is turned on and that the controller indicates no faults.
• Locate the brand, model, and installation date on the label affixed to the side of the tank.

Frequently Asked Questions About Hot Water Shortages

What is the typical waiting time for hot water to return after it runs out?

The waiting time varies based on the type of system. Electric tanks on a standard tariff and gas storage tanks begin reheating immediately. An electric tank on Tariff 31 or Tariff 33 only reheats when the network powers the circuit, which may leave it cold until the next off-peak period. If the water remains cold the next morning, it’s advisable to have the system inspected.

How can I determine whether I need a larger hot water system or a new one?

If the issue arose after your household size increased and the system operates well otherwise, it likely indicates a need for a larger system. Alternatively, if the problem has developed gradually in an older tank or if the tank shows signs of rust, leaks, or unusual noises, replacement is probably the more sensible option.

Is it possible to increase the size of my hot water tank?

While you cannot physically enlarge an existing hot water tank, you can replace it with a larger system. We assess the number of residents in the household, their hot water usage patterns, and the system’s energy source to recommend an appropriately sized tank and system type.

What is the typical duration for replacing a hot water system?

Most hot water system replacements are completed within a single day, especially when the new system matches the type and size of the old one.

Professional Hot Water Solutions in Caboolture, Morayfield, and Moreton Bay

Creek to Coast Plumbing has proudly served households throughout Caboolture, Morayfield, and the Moreton Bay region since 2012. Our licensed plumbers and gas fitters specialise in the installation and servicing of electric, gas, solar, and heat pump hot water systems. We will identify the cause of your hot water shortages, explain your options, and provide a quote before any work begins.

Contact us at 1300 793 962 or send a message to Damian or our team detailing your hot water issue and when it occurs. You can also learn more about our hot water services in Caboolture.