Choosing an Energy-Efficient Hot Water System: What You Should Know
Hot water is essential for everyday comfort — from showers and dishwashing to laundry. But did you know that hot water heating accounts for up to 25% of your household energy bill in Australia?
Choosing the right energy-efficient hot water system can save you hundreds of dollars annually, reduce greenhouse gas emissions, and improve the sustainability of your home.
In this guide, we break down the different types of systems, energy-saving features to look for, and how to choose the best option for your home.
✅ Why Energy Efficiency Matters
- Lower energy bills long-term
- Reduced environmental impact
- Better performance and reliability
- Eligible for government rebates and incentives
Choosing the wrong system — or an oversized one — can waste both energy and money.
🔍 Types of Hot Water Systems (and Their Efficiency)
1. Electric Storage Systems
- Heats and stores water in a tank
- Cheapest to install but most expensive to run
- Best for low-use households on off-peak electricity
⚠️ Not recommended for energy efficiency unless powered by solar or off-peak tariffs
2. Gas Storage or Instantaneous (Continuous Flow)
- Gas heats water either in a tank or on-demand
- More efficient than electric systems
- Requires natural gas connection (LPG possible but more expensive)
🔥 Continuous flow models only heat water when needed = more efficient
Look for 6-star+ rated systems for best performance
3. Solar Hot Water Systems
- Uses rooftop solar panels to heat water
- Includes a backup booster (electric or gas)
- Highest energy savings and lowest running costs
☀️ Ideal for sunny climates — can save up to 80% on water heating costs
Eligible for STCs (Small-scale Technology Certificates) and rebates
4. Heat Pump Systems
- Extracts heat from the air to heat water (like a reverse-cycle air conditioner)
- Runs on electricity but uses up to 70% less energy than traditional electric systems
🌡️ Best in moderate to warm climates
Considered a renewable energy system in some rebate programs

🧮 How to Choose the Right System
1. Household Size
| People | Suggested Tank Size (Electric) | Gas/Instantaneous |
| 1–2 | 80–160L | 16–20L/min |
| 3–4 | 160–315L | 20–26L/min |
| 5+ | 315L+ | 26L/min+ |
📌 Oversizing wastes energy. Undersizing causes frustration.
2. Climate & Roof Space
- Solar systems need good sun exposure and enough roof space
- Heat pumps work best in mild climates
- Cold climates may require boosters or insulated tanks
3. Energy Source Availability
- Natural gas access? → Consider gas or solar-gas
- No gas? → Electric or heat pump
- Looking to go off-grid? → Solar with battery backup
4. Budget & Rebates
- Upfront costs: Heat pumps & solar systems cost more initially
- Running costs: Solar and heat pumps offer biggest long-term savings
- Check for state and federal rebates, STCs, and energy efficiency incentives
♻️ Energy-Saving Features to Look For
- ✅ High star rating (energy labels)
- ✅ Insulated tank (reduces heat loss)
- ✅ Smart controllers or timers
- ✅ Frost protection (for solar systems in cold climates)
- ✅ Temperature control valves (improves safety and reduces overheating)
🛠️ Installation & Maintenance Tips
- Always use a licensed plumber to install or replace a hot water system
- Schedule regular maintenance every 2–5 years (depending on system)
- Flush tanks and clean filters as recommended
- Install near points of use where possible (reduces heat loss in pipes)
✅ Final Thoughts
Choosing an energy-efficient hot water system is a smart investment that benefits your wallet and the environment. Whether you’re building, renovating, or upgrading an old unit, consider your household size, climate, and available energy sources before deciding.
For the best results, speak to a licensed plumber or hot water specialist who can guide you through the selection and installation process — and help you claim available rebates.
🔧 Need Help Choosing or Installing a Hot Water System?
Alliance Plumbing can help you choose the best hot water system for your home, lifestyle, and budget. From energy-efficient heat pumps to solar and gas solutions, their licensed team ensures reliable, compliant installation and long-term performance.
👉 Contact Alliance Plumbing today for expert advice and a free quote on your next hot water upgrade.