01 Oct Hot Water Running Out Fast?
Here’s Why (And What We Can Do About It)
I get this call at least three or four times a week: “Richard, our hot water used to last forever, but now it’s running out halfway through the second shower. What’s going on?”
It’s one of the most common complaints I hear from Brisbane homeowners, and after 30+ years of installing, repairing, and replacing hot water systems across South East Queensland, I can tell you it’s rarely a simple answer. Sometimes it’s the system itself, sometimes it’s how you’re using it, and sometimes it’s a combination of factors that have been building up over time.
Today, I want to walk you through exactly why your hot water seems to be running out faster than it used to, what the warning signs are, and most importantly, what we can actually do about it. Because nobody wants to be the one to cop the cold shower at the end of the morning rush, right?
The Most Common Reasons Your Hot Water Runs Out Quickly
1. Sediment Build-Up in Your Storage Tank
This is the big one, especially here in Brisbane where our water is relatively hard and full of minerals. Over time, sediment – basically calcium, magnesium, and other minerals – settles at the bottom of your hot water tank. This sediment layer acts like an insulator between the heating element (or gas burner) and the water, making your system work harder and reducing the amount of hot water available.
I’ve drained tanks that have had 10-15cm of sediment at the bottom. That’s a huge amount of space that should be holding hot water but is instead filled with crusty mineral deposits. When I show clients the muck that comes out of their tanks, they’re genuinely shocked.
How to spot it:
- Hot water runs out faster than it used to
- Rumbling or popping noises from the tank
- Takes longer for water to heat up
- Higher electricity or gas bills without explanation
If your hot water system is more than 5 years old and you’ve never had it serviced, sediment build-up is almost certainly affecting your hot water supply.
2. Failing Heating Elements (Electric Systems)
Electric hot water systems have heating elements that can deteriorate over time. Brisbane’s water quality, power fluctuations during storm season, and general wear and tear all take their toll.
Here’s what happens: electric systems typically have two elements – one at the bottom and one higher up. If the bottom element fails, you’ll only be heating the top portion of the tank. That means you might still get hot water, but nowhere near as much as you should.
I’ve replaced countless heating elements across Brisbane, and it’s often a straightforward fix that makes a massive difference. The tricky part is diagnosing it correctly, because a failing element can show similar symptoms to sediment build-up or a faulty thermostat.
3. Thermostat Issues
Your hot water system’s thermostat controls the temperature of the water in the tank. If it’s not set correctly or if it’s malfunctioning, you won’t be heating water to the optimal temperature.
The ideal setting for most households is 60-65°C. This temperature is hot enough to kill legionella bacteria (which is a serious health concern) but not so hot that you’re wasting energy or risking scalding. If your thermostat has drifted lower – say, down to 45-50°C – you’ll notice the hot water doesn’t last as long and doesn’t feel as hot.
Sometimes thermostats fail gradually. You might not notice the temperature dropping a degree or two at a time, but over months, it can make a significant difference to your hot water supply.
4. Increased Household Water Usage
This one’s less about the system and more about lifestyle changes. I see this all the time with Brisbane families:
- Kids getting older and taking longer showers
- Teenagers who seem to live in the bathroom
- New washing machine or dishwasher that uses hot water
- Someone working from home and using hot water during the day
- Installing a new rain shower head (which can use significantly more water)
Sometimes the hot water system hasn’t changed at all – the household’s demands on it have increased beyond what it was originally sized for.
5. Tempering Valve Problems
The tempering valve (also called a temperature limiting valve) mixes cold water with your hot water to prevent scalding. It’s a safety device that’s required by Australian Standards, but if it’s faulty or not adjusted correctly, it can dramatically affect your hot water performance.
If the tempering valve is allowing too much cold water to mix in, you’ll feel like your hot water isn’t hot enough or runs out quickly. You’re using more “hot” water to achieve the same temperature, which depletes your tank faster.
I’ve seen tempering valves that have calcified or corroded internally, especially on older systems or in areas with particularly hard water. It’s not something most homeowners think to check, but it can be the cause of mysterious hot water problems.
6. Leaking Hot Water System
A leak in your hot water system – even a small one – can significantly reduce your available hot water and waste energy. Some leaks are obvious (water pooling around the base of the unit), but others can be sneaky.
Common leak points:
- Pressure relief valve (the valve on top or side that’s designed to release pressure)
- Element gaskets on electric systems
- Corroded tank (especially on older systems)
- Pipe connections at the top of the unit
- Sacrificial anode rod access point
If you’re noticing damp patches, rust stains, or actual dripping from your hot water system, don’t ignore it. What starts as a minor leak can quickly become a major problem, and a leaking tank usually means you need a full replacement.
7. System Age and Deterioration
Hot water systems have a finite lifespan, typically:
- Electric storage systems: 10-15 years
- Gas storage systems: 10-12 years
- Instantaneous gas systems: 15-20 years
- Heat pump systems: 10-15 years
- Solar hot water systems: 15-20 years (with regular maintenance)
As systems age, they become less efficient. The insulation deteriorates, internal components wear out, and the tank itself can corrode from the inside. If your system is approaching or past its expected lifespan, reduced hot water capacity might be a sign it’s time for a replacement.
I’ve installed hot water systems across all of Brisbane – from the CBD to Ipswich and down to parts of the Gold Coast – and I always tell clients the same thing: once a system starts showing multiple issues and it’s over 10 years old, you’re often better off replacing than repairing.
How Brisbane’s Climate Affects Your Hot Water System
Living in Brisbane’s subtropical climate creates some unique challenges for hot water systems that people in cooler climates don’t deal with.
Summer considerations:
- Incoming water temperature is much warmer (sometimes 25-28°C in summer vs 15-18°C in winter)
- Systems don’t need to work as hard to heat water
- You use less hot water for showers and washing
- Can feel like your system is performing better
Winter considerations:
- Incoming water temperature drops significantly
- System needs to work much harder to achieve the same temperature
- You use more hot water for longer, hotter showers
- Hot water runs out faster because you’re drawing more and the recovery time is longer
This is why problems often become noticeable in winter. A system that’s starting to struggle might cope fine during summer but fails to meet demand when the temperatures drop.
The Right System Size for Brisbane Households
One of the most common issues I see is hot water systems that were never the right size for the household in the first place. Here’s my general rule of thumb for Brisbane families:
Storage systems:
- 1-2 people: 125-160 litre tank
- 3-4 people: 250-315 litre tank
- 5+ people: 400 litre tank
However, these are just guidelines. Your actual needs depend on:
- Shower habits (quick rinses vs long, hot showers)
- Simultaneous hot water use (morning rush with multiple showers)
- Washing machine and dishwasher usage
- Bath vs shower preferences
- Whether you have teenagers (they use significantly more hot water!)
I always do a proper assessment before recommending a system size. There’s no point installing a 315-litre tank if your family’s usage patterns mean you’d be better served by an instantaneous system or a smaller tank with off-peak boosting.
When to Repair vs When to Replace Your Hot Water System
This is the question everyone asks me: “Richard, should we fix it or replace it?”
Here’s my honest assessment process:
Consider repairing if:
- The system is less than 7 years old
- It’s a single, identifiable problem (like a heating element or thermostat)
- The repair cost is less than 30% of replacement cost
- The tank itself is in good condition with no corrosion
- You’re happy with the system type and size
Consider replacing if:
- The system is over 10 years old
- You’ve had multiple repairs in the last 2 years
- The tank is corroded or leaking
- Your hot water needs have changed significantly
- You want to upgrade to a more energy-efficient system
- Repair costs are approaching 50% or more of replacement cost
I’m not one of those plumbers who’ll push you towards a replacement if a repair will genuinely solve the problem. But I’ll also be honest with you if I think you’re throwing good money after bad on an old system that’s on its last legs.
Your Hot Water System Options in Brisbane
If replacement is on the cards, you’ve got several options. Each has pros and cons for Brisbane’s climate and lifestyle:
Electric Storage Systems
Pros:
- Lower upfront cost
- Simple installation
- Reliable technology
- Works anywhere (no gas connection needed)
Cons:
- Higher running costs (electricity is expensive)
- Slower recovery time when tank runs out
- Can be large and bulky
- Off-peak systems mean no hot water boost during the day
Best for: Budget-conscious households, homes without gas connection, consistent usage patterns.
Gas Storage Systems
Pros:
- Faster recovery time than electric
- Lower running costs than electric storage
- Can boost during the day if needed
- Generally more energy-efficient
Cons:
- Requires gas connection
- Higher upfront cost than electric
- Still uses a storage tank (space requirement)
- Annual gas appliance servicing recommended
Best for: Homes with natural gas connection, families with variable usage, those wanting lower running costs.
Instantaneous Gas Systems
Pros:
- Endless hot water (never runs out)
- Very energy-efficient (only heats what you use)
- Compact size
- Lower running costs
- Great for large families or simultaneous use
Cons:
- Higher upfront cost
- Requires adequate gas supply (sometimes need larger gas meter)
- Flow rate can be affected by simultaneous outlets
- Not suitable for all homes
Best for: Large families, homes with high hot water demand, those who want endless supply, energy-conscious households.
This is my personal favourite for most Brisbane homes, especially families. I’ve installed hundreds of instantaneous systems across South East Queensland, and the feedback is consistently positive.
Heat Pump Systems
Pros:
- Very energy-efficient (uses 60-70% less electricity than standard electric)
- Government rebates sometimes available
- Good for the environment
- Lower running costs over time
Cons:
- High upfront cost
- Requires outdoor space with good airflow
- Can be noisy (like an air conditioner)
- Performance affected by ambient temperature
- Not ideal for shaded locations
Best for: Environmentally conscious households, homes with appropriate outdoor space, those planning to stay long-term (to recoup the investment).
Solar Hot Water Systems
Pros:
- Lowest running costs
- Excellent for the environment
- Government rebates often available
- Great in Brisbane’s sunny climate
- Can include gas or electric boosting for cloudy days
Cons:
- Highest upfront cost
- Requires roof space and appropriate orientation
- More complex installation
- Regular maintenance essential
- Boosting costs if weather is poor
Best for: Long-term homeowners, environmentally conscious families, homes with appropriate roof space and orientation.
I’ve installed all of these systems countless times across Brisbane, and I can give you honest advice about what will work best for your specific situation – your home, your budget, your family’s needs, and your location.
Improving Your Hot Water System Performance
If your system is relatively new or you’re not ready for a replacement, here are some practical ways to improve performance:
1. Service Your System Regularly
Annual servicing should include:
- Checking and testing the pressure relief valve
- Inspecting the sacrificial anode rod (this prevents internal corrosion)
- Flushing sediment from the tank
- Checking heating elements or gas burner
- Testing the thermostat
- Inspecting all connections for leaks
- Checking the tempering valve operation
Regular servicing can extend your system’s life by years and maintain optimal performance.
2. Adjust Your Usage Patterns
Simple changes can make a big difference:
- Stagger morning showers instead of everyone showering back-to-back
- Use cold water for washing clothes (modern detergents work fine in cold water)
- Fix any dripping hot water taps promptly
- Install water-efficient shower heads
- Consider shorter showers (even reducing by 2 minutes helps significantly)
3. Insulate Your Hot Water Pipes
If your hot water system is located away from your main bathroom or kitchen, you’re losing heat through the pipes. Insulating hot water pipes is inexpensive and can reduce heat loss by up to 50%, meaning hot water arrives faster and stays hotter.
4. Check Your Tempering Valve Setting
If your tempering valve is set too conservatively, you’re mixing more cold water than necessary. A licensed plumber (like me!) can adjust this to the optimal setting for safety and performance.
5. Consider a Timer or Smart Controller
For electric systems, you might be able to install a timer or smart controller that allows limited hot water boosting during peak times while still taking advantage of cheaper off-peak electricity rates.
Hot Water Solutions for Commercial and Industrial Clients
I work with numerous commercial clients across Brisbane – medical centres, aged care facilities, apartment buildings, restaurants, and industrial sites. Commercial hot water demands are completely different from residential, and solutions need to be designed accordingly.
For property managers dealing with apartment buildings, I recommend:
- Regular maintenance schedules for all units
- Centralized systems with individual metering where appropriate
- Legionella management plans (this is crucial for commercial buildings)
- Emergency response agreements for 24/7 callouts
For hospitality and food service operations, hot water is critical to operations. We design systems that provide reliable supply even during peak service times, with redundancy built in where possible.
Emergency Hot Water Solutions
If your hot water system has completely failed and you need an urgent solution, Alexander Gas and Plumbing Co provides 24/7 emergency services across all Brisbane, Ipswich, and selected Gold Coast areas.
I understand that losing hot water isn’t just an inconvenience – it affects your entire household or business operation. We keep a range of hot water systems in stock and can often provide same-day installation for emergencies.
Making the Right Decision for Your Brisbane Home
Choosing the right hot water solution comes down to understanding your specific needs and circumstances. I’ve been doing this for over 30 years, and I’ve learned that there’s no one-size-fits-all answer.
When you call Alexander Gas and Plumbing Co, here’s what you get:
- A thorough assessment of your current system and your household’s needs
- Honest advice about whether repair or replacement makes more sense
- Clear explanations of all your options with transparent pricing
- Professional installation with all necessary compliance (Plumbing Licence 28840, Gas Licence L31 902)
- We clean up after ourselves (yes, we actually do!)
- Ongoing support and maintenance
I’m a family-owned, local Brisbane business, and I treat every client like family. If I wouldn’t recommend something for my own home, I won’t recommend it for yours.
Don’t Wait Until You’re Out of Hot Water
If you’ve noticed your hot water running out faster, strange noises from your system, discoloured water, or higher energy bills, don’t wait until it fails completely. An assessment now can save you from an emergency replacement later – and emergency situations rarely give you time to make the best decision about what system to install.
Give us a call, and we’ll come out to have a look. I’ll give you straight answers about what’s going on and what your options are. No pressure, no rubbish – just honest advice from someone who’s been in the plumbing game for three decades.
Visit us at www.alexandergasandplumbing.com.au or call for emergency hot water services available 24/7 across Brisbane.
Frequently Asked Questions
How long should hot water last in a typical household?
For a properly sized and functioning storage system, you should get approximately 10-15 minutes of continuous hot water per person in the household. For example, a family of four with a 315-litre tank should comfortably handle four consecutive 10-minute showers. If you’re running out before this, your system is either too small for your needs, needs servicing, or is malfunctioning. Instantaneous systems provide endless hot water, though flow rate can be affected if multiple outlets are used simultaneously.
Why does my hot water run out faster in winter?
Winter affects hot water supply in several ways. First, the incoming cold water temperature drops from around 25°C in summer to 15-18°C in winter, meaning your system must work harder to heat the water to the same temperature. Second, people naturally take longer, hotter showers in winter, using more hot water. Third, the recovery time between hot water uses increases because the system is working from a colder starting point. This is completely normal, but if it’s causing problems, your system might be undersized or need servicing.
What temperature should my hot water system be set to?
The Australian Standards recommend 60°C at the storage tank to prevent legionella bacteria growth, with a tempering valve reducing it to 50°C at the taps for safety. This is the setting I recommend for most Brisbane homes. Setting it lower saves energy but increases health risks. Setting it higher wastes energy and increases scalding risk. If you’re unsure about your current setting, a licensed plumber can check and adjust it for you.
How often should I service my hot water system?
I recommend annual servicing for all hot water systems. This should include checking the pressure relief valve, inspecting the sacrificial anode rod, flushing sediment from storage tanks, and testing all safety devices. For commercial systems or homes with very hard water, you might need servicing twice a year. Regular servicing can extend your system’s lifespan by 3-5 years and maintain optimal efficiency.
What’s the most energy-efficient hot water system for Brisbane?
For Brisbane’s climate, solar hot water systems are the most energy-efficient, followed by heat pump systems, then instantaneous gas systems. However, “most efficient” doesn’t always mean “best for your home.” Solar and heat pump systems have high upfront costs and specific installation requirements. For many Brisbane families, an instantaneous gas system offers the best balance of efficiency, endless hot water, and reasonable upfront cost. I can assess your specific situation and recommend what will actually work best for you.
How much does it cost to replace a hot water system in Brisbane?
Replacement costs vary significantly based on system type and installation complexity. As a rough guide: electric storage systems $900-$2,500, gas storage systems $1,500-$3,000, instantaneous gas systems $2,000-$4,500, heat pump systems $3,500-$6,000, and solar systems $4,000-$8,000+. These prices include the unit and standard installation. I always provide detailed written quotes before starting work, so there are no surprises.
Why is my hot water brown or rusty-coloured?
Brown or rusty water from your hot water system usually indicates internal corrosion of the tank. This happens when the sacrificial anode rod has depleted and is no longer protecting the steel tank. Once you’re seeing discoloured water, the tank is usually beyond saving and needs replacement. Don’t ignore this – a corroded tank can develop leaks without warning. Schedule an inspection immediately if you notice discoloured hot water.
Can sediment build-up in my hot water tank be fixed?
Yes, sediment build-up can be fixed by flushing the tank. This involves draining the tank completely and flushing fresh water through until it runs clear. For systems with severe sediment build-up, we might need to do this several times or use more aggressive flushing techniques. If your system has been neglected for many years, heavy sediment can damage heating elements or prevent proper tank drainage. Regular flushing (annually or every two years) prevents serious sediment problems from developing.
Do you provide emergency hot water replacement in Brisbane?
Yes, Alexander Gas and Plumbing Co provides 24/7 emergency hot water services across all Brisbane, South East Queensland, Ipswich, and selected Gold Coast areas. We understand that losing hot water is a genuine emergency for families and businesses. We keep common hot water systems in stock and can often provide same-day replacement for urgent situations. As a local, family-owned Brisbane business, we look after our clients like family – even when emergencies happen at inconvenient times.
With over 30 years in the plumbing industry he provides a level headed and experience approach to all client related work.He is genuine person with a keen interest in family, friends and helping others.
He holds Queensland Plumbing Licence 28840, Gas Licence L31 902, QBCC License 12 654 79, and Building Assets and Services Contractor licence 860 066.
Rich believes in educating clients about their plumbing systems and providing honest advice about when professional help is needed.
He founded Alexander Gas and Plumbing Co in 2013 to provide personal, trustworthy service to Brisbane families and businesses.
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