Laundry detergents work better in “soft water.” Borax naturally softens hard water making almost all detergents more effective so adding 1/2 cup to each full load of washing with your normal detergent will boost your detergent greatly, resulting in a whiter and brighter wash.
The ‘hardness’ of water relates to the amount of minerals it contains, such as mainly calcium and magnesium, and to a lesser degree iron, manganese and barium salts.
The Australian scale is as follows:
| Water Type | Hardness in mg/L |
| Soft | 0–60 |
| Moderately hard | 61–120 |
| Hard | 121–180 |
| Very hard | ≥ 181 |
And here is a guide to the water hardness in Australian capital cities:
| City | Total Hardness as Calcium Carbonate mg/L |
| Melbourne | 10 – 26 |
| Hobart | 5.8 – 34.4 |
| Darwin | 31 |
| Canberra | 40 |
| Sydney | 39.4 – 60.1 |
| Perth | 29 – 226 |
| Brisbane | 100 |
| Adelaide | 134 – 148 |
