The right pump should deliver the water you need, at the pressure you need - even when more than one tap is running.

For household pressure pumps, there are three main things to consider: water demand, pressure and your property’s layout.

1. How much water will you use at once?

Water flow is measured in litres per minute (L/min).

Think about what might run together: showers, kitchen taps, washing machines, toilets and garden irrigation. You don’t need to add up every outlet in the house - focus on those you’re likely to use at the same time.

As a rough starting point, allow around 10 L/min for a typical tap or shower. Actual demand varies, especially with large shower heads, baths and irrigation, so check the flow requirements of your fittings where possible.

For example, two showers using 10 L/min each, plus a kitchen tap using 10 L/min, would need approximately 30 L/min while all three are running.

2. What pressure do you need?

Flow tells you how much water is delivered. Pressure determines how strongly it arrives at your taps.

Pump specifications often express pressure as “head”, measured in metres:

• 10 metres of head is approximately 1 bar, or 14.2 PSI.
• 30 metres of head is approximately 3 bar, or 42.7 PSI.

The right pressure depends on your plumbing, appliances and hot-water system. If you have a low-pressure hot-water cylinder, let us know before choosing a pump so we can help check compatibility.

3. What does your pump need to overcome?

Your pump also needs to account for:

• Height differences between the water source, pump and outlets.
• Pressure losses through pipes, bends, valves and fittings.
• Resistance through filtration and other equipment.
• Whether water flows into the pump or must be drawn up from below it.

Long or narrow pipes can reduce the flow and pressure available at the house. A pump drawing water uphill also needs suitable suction conditions.

Understanding a pump curve

A pump curve shows how much flow a pump can deliver at different pressures.

The horizontal axis shows flow, usually in litres per minute. The vertical axis shows head, usually in metres.

Maximum flow and maximum head are separate limits—they are not delivered together. Choose a pump that can supply your required flow at the total head your system needs, within the manufacturer’s recommended operating range.

For example, if you need 30 L/min, check the pressure the pump delivers at 30 L/min - not just the maximum figures on its label.

Let us help you choose

You don’t need to work it all out yourself. Send us:

• Your water source: tank, bore or another supply.
• The number of bathrooms and outlets likely to run together.
• Any irrigation or other high-demand uses.
• Approximate pipe lengths and internal pipe diameter, if known.
• Height differences between the source, pump and house.
• Details of your hot-water system and any filtration.
• Your existing pump model, if you’re replacing one.

Photos of your current setup are helpful too.

Call 09 294 7555 or email sales@pumpandpurify.co.nz for straightforward advice on choosing a pump that suits your property.

Great water. Sorted.