September 3, 2023

Hot Water System – Finding Your Perfect Fit: What Size Do You Need?

4 minute read

Person in a shower with a distressed expression, hugging themselves as water runs down, possibly due to issues with the hot water system. A Doran Plumbing & Drainage logo is in the upper left corner.

Choosing the right Hot Water System size is a crucial decision for any Australian homeowner. A system that is too small may leave you shivering in cold water, while one that is too large can result in unnecessary energy consumption and higher utility bills. To make an informed choice and ensure a consistent supply of hot water for your household needs, let’s explore the factors to consider when determining what size hot water system you need in metric measurements.

1. Assessing Hot Water Demand:

The first step in choosing the right hot water system size is to evaluate your household’s hot water usage. Consider the number of people living in your home and their typical hot water habits. Take into account the frequency of showers, baths, laundry, and dishwashing. Larger families with higher hot water demand will require a larger system, while smaller households may get by with a more modest unit.

2. Understanding Litre Capacity:

Hot water systems come in different litre capacities, typically ranging from 115 to 300 litres or more. The litre capacity refers to the amount of hot water the system can store and supply. As a general guideline, a 115-litre hot water system is suitable for a single-person household or a vacation home, while a 150 to 190-litre unit can adequately serve a small family. For larger families or homes with high hot water demand, a 190 to 300-litre hot water system is more appropriate.

3. Consider Recovery Rate:

Recovery rate refers to how quickly a hot water system can reheat the stored water after use. If your household frequently uses hot water simultaneously (e.g., multiple showers in the morning), a high recovery rate is essential to ensure a steady supply of hot water. Pay attention to the recovery rate listed on the hot water system’s specifications to match it with your household’s peak hot water usage.

4. Account for Fuel Type and Efficiency:

The fuel type of your hot water system can also influence its size. Gas hot water systems tend to have faster recovery rates than electric ones, making them suitable for households with higher hot water demand. Additionally, consider the energy efficiency rating of the hot water system. A more efficient unit can provide the same hot water with a smaller tank, potentially saving you money on energy costs.

5. Space and Installation Considerations:

Before finalizing your decision, ensure that the hot water system’s physical size fits the available space for installation. Measure the space carefully, taking into account clearance requirements and access for maintenance. If you’re considering a tankless hot water system, they require less space, but their sizing is based on flow rate rather than litres, so ensure it meets your hot water needs.

6. Consult a Professional:

If you find the process overwhelming or are unsure about the best hot water system size for your specific needs, don’t hesitate to consult a plumbing professional. They can assess your household’s hot water usage, take into account any unique requirements, and recommend the ideal hot water system size to meet your needs efficiently.


Selecting the right system size is a vital step in ensuring your Australian household’s comfort and energy efficiency. By evaluating your hot water demand, understanding litre capacity, considering recovery rate, and accounting for fuel type and efficiency, you can confidently make an informed decision. When in doubt, seek the advice of a plumbing expert to find the perfect fit and enjoy a consistent supply of hot water for years to come.

Penetrator Blocked Drains - Doran Plumbing and Drainage
The blocked drain specialist – servicing Brisbane

Penetrator (aka Gavin) has been plumbing for over 20 years.  He has worked alongside other plumbers and in both commercial and residential plumbing.  His passion within plumbing has always been the challenge of a blocked drain…He thrives on defeating the blockages and will continue until he is satisfied he has 110% done the best he can.  His work ethic is unsurpassable and his workmanship is second to none. If there’s a blocked drain – Penetrator is your man!

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