On average you should estimate to have a capacity of 35L – 40L of water storage per person for a gas system and slightly more for electric.
However, you are best to judge this on your own consumption patterns.
Please note that this does not always mean that for an average family size of 4 people you need to have 4 times the above rate (ie. 4 x 40L = 160L Storage), as it depends on when you are using the water. If you are using it throughout the entire day, it may mean that you never need to consume 160L in one go and therefore a smaller unit may suffice.
| Off-peak | |
|---|---|
| Number of people | Capacity (Litres) |
| 1 – 3 | 160 |
| 2 – 4 | 250 |
| 3 – 6 | 315 |
| 5 – 8 | 400 |
| Peak rate | |
|---|---|
| Number of people | Capacity (Litres) |
| 1 | 25 |
| 1 – 2 | 50 |
| 2 – 3 | 80 |
| 3 – 5 | 125 |
Source: Choosing a hot water system, Sustainable Energy Authority Victoria
| Tank storage | |
|---|---|
| Number of people | Capacity (Litres) |
| 1 – 3 | 90 |
| 2 – 4 | 130 |
| 3 – 5 | 170 |
| 4 – 6 | 200 |
| 5 – 9 | 260 |
| Continuous flow | |
|---|---|
| #outlets at one time | Flow rate (Lt/min) |
| 1 | 16 |
| 2 | 20 |
| 2 – 3 | 24 |
| 3+ | 32 |
Source: Choosing a hot water system, Sustainable Energy Authority Victoria
| Number of people | Hot water required (Lt/day) |
|---|---|
| 1 – 2 | 120 |
| 3 – 4 | 200 |
| 5 – 6 | 300 |
| Approximate storage tank size | Collector area (m2) |
|---|---|
| 180 | 2 |
| 300 | 4 |
| 440 | 6 |
Source: Choosing a hot water system, Sustainable Energy Authority Victoria
