When it comes to choosing the right hot water system, size matters—a lot. If your system is too small, you’ll end up running out of hot water in the middle of a shower. If it’s too big, you’ll waste energy and money heating water you don’t even use. So, how do you figure out the perfect size for your home?
In this guide, we’ll walk you through the key factors to consider when selecting a hot water system, how to estimate the right capacity for your household, and why professional Hot Water System Installation is essential for long-term performance.
Why Hot Water System Size Is Important
A hot water system is one of the hardest-working appliances in your home. From showers and dishwashing to laundry and cleaning, your household relies on it daily. Choosing the wrong size can lead to:
- Cold showers when demand is high
- Higher energy bills if you’re heating unnecessary water
- Increased wear and tear on the system
- Frustration for your entire family
At SA Hot Water, we see homeowners make this mistake all the time. The good news? With the right guidance, you can easily avoid it.
Key Factors to Consider When Choosing a Size
Before you settle on a specific hot water system, keep these important factors in mind:
1. Number of People in the Household
This is the single biggest factor. More people mean more showers, more dishes, and more laundry.
- 1–2 people → small system (about 50–160L storage or 16L/min continuous flow)
- 3–4 people → medium system (about 160–250L storage or 20–24L/min continuous flow)
- 5+ people → large system (about 250–400L storage or 26–32L/min continuous flow)
2. Daily Hot Water Usage
Think about your lifestyle. Do multiple people shower in the morning at the same time? Do you use hot water heavily for cooking and laundry? Families with teenagers, for example, often need a bigger system.
3. Type of Hot Water System
There are two main types of hot water systems:
- Storage systems: Heat and store a set amount of water in a tank. Once used, they need time to reheat.
- Continuous flow (instantaneous) systems: Heat water on demand, so you never technically run out, but the flow rate limits how much hot water can be used at once.
4. Energy Source
Gas, electricity, solar, or heat pump—all have different heating speeds and capacities. For example:
- Gas continuous flow systems are great for medium to large families.
- Electric storage tanks suit smaller households but can be more expensive to run.
- Solar systems are eco-friendly and cost-efficient, but need the right size to ensure a backup supply.
5. Peak Usage Times
If everyone showers in the morning, you’ll need a bigger storage system or a continuous flow unit that can handle multiple outlets at once.
Storage Hot Water System Sizes
Here’s a quick guide to choosing the right storage tank size:
- Small home (1–2 people): 50–160 litres
- Medium home (3–4 people): 160–250 litres
- Large home (5+ people): 250–400 litres
Keep in mind that electric tanks usually need to be larger, since they heat more slowly, while gas systems can get away with smaller tanks because they reheat faster.
Continuous Flow Hot Water System Sizes
These systems don’t store water, but they’re rated by how many litres of hot water they can supply per minute.
- 1–2 people: 16L/min
- 3–4 people: 20–24L/min
- 5+ people: 26–32L/min
If you want to run multiple showers and taps at the same time, go for the higher end of the range.
Common Mistakes to Avoid
- Going too small: Constantly running out of hot water is frustrating and puts extra pressure on the system.
- Going too big: Oversized systems cost more upfront and increase energy bills unnecessarily.
- Ignoring efficiency: A well-sized, energy-efficient system saves money long-term.
- DIY installation: Always trust professional Hot Water System Installation to ensure safety and warranty protection.
How to Estimate Your Hot Water Needs
Here’s a simple way to work it out:
- Count the number of people in your home.
- Estimate daily showers (average shower uses 40–50 litres).
- Add extra use for dishwashing and laundry.
- Consider peak usage times.
Example: A family of four, with two teenage kids, might use:
- 4 showers × 50L = 200L
- Laundry = 50L
- Dishwashing = 30L
- Total ≈ 280L/day
In this case, a 250–315L storage tank or a 24L/min continuous flow system would be ideal.
Why Professional Guidance Matters
Every household is different, and small details make a big difference. For example:
- Gas availability
- Roof space for solar
- Energy tariffs
- Bathroom layout and water pressure
That’s why speaking with an expert team like SA Hot Water is the best way to get it right. We help you choose, install, and maintain the perfect system for your needs.
Final Thoughts
The right hot water system size is all about balance. Too small, and you’ll be left with cold showers. Too big, and you’ll pay more than necessary. By considering your household size, usage patterns, and energy source, you can find the perfect fit.
If you’re unsure, don’t guess. Get expert advice from SA Hot Water and ensure your system is installed properly for years of reliable hot water.