What pump do I need?
| Pumps are rated by water flow in litre per minute (lpm) and pressure in metre head (m) or kilopascals (kpa) and by their ability for suction lift. |
Water Flow
| Work out what you need by adding up the consumption of outlets that may be operating at the same time. This is dependant on the number of people in the house using outlets at the same time. For example: |
| Usage by outlet | Litre per minute (lpm) |
| Toilet | 9 |
| Standard shower head | 10-15 |
| Water saving shower head | 7 |
| Standard tap | 10 |
| Dishwasher | 15 |
| Washing Machine | 10-15 |
| Garden Hose | 20 |
| Lawn sprinkler | 10-15 |
So normal water requirements for houses
| House size | Average Total litres per minute |
| Small cottage | 10-20 |
| Small house | 20-30 |
| Medium house | 30-50 |
| Large House | 50-90 |
Water Pressure Consideratons
Pumps sucking up from underground tanks or wells
| You need a jet pump as they have the ability to self prime and also suck from a lower source or Submersible pumps that sit in the water source. Thus suction lift is not an issue. |
Pumps at the base of a tank with no suction lift required
| Either a jet pump or a multistage pump.Multistage pumps can have higher pressure than jet pumps but have minimal suction lift capacity. |
Long distance from source to house
| The longer distance to pump the more pressure is required as friction in the pipe causes pressure loss |
High set or low set house or elevated from the water source
| High set houses require higher pressure than low set houses |
| To calculate pressure requirements you need to calculate suction lift if required and the total pressure required to pump through the pipes plus the height from pump to highest outlet plus the pressure required at the delivery outlet. |