How To Choose The Right Water Pump

Electric water pumps are a fantastic way to move water around your house and your property but there are so many to choose from, how do you choose the correct pump for your application?

The staff at The Water Pump Warehouse are here to help you choose the right pump.

First you need to understand a few key terms.

Water flow volume– How much water and how fast can your pump move water? Pumps are usually rated in litres per minute or litres per hour. Consider how much water you want to move. If you want to empty a swimming pool containing 15,000 litres, a 100 litres per hour pump would take 150 hours to empty the pool. But a larger pump rated at 30,000 litres per hour could do the job in half an hour.

Head pressure or lift pressure– This is a measurement of how hard the pump can push water. We measure this in meters, psi or kpa. We usually talk about the Head pressure and this refers to a theoretical measurement of how far your pump could push water up a vertical pipe. This can be important if you want to push water from your dam or a tank up to your property that is 50m above your tank. Your house could be at the top of a hill at a height that is 50m above your dam. We have a wide range of pumps that can push water up to 160m vertically. But remember the longer the pipe and the more bends it has, the more drag on water flow.

PSI (or Pounds per square inch pressure) or KPA Pressure– Manufacturers or retailers will sometimes confuse you with figures. This is just another way of expressing water head pressure mentioned above. To convert on PSI to head pressure, multiply by 2.31. For instance, 15psi becomes 35 feet of head pressure or roughly 12m head pressure. KPA is the metric way of measuring pressure. KPA is short for Kilopascal. 10 kPa is the equivalent to 1.45psi or 1.0m of head pressure.

Suction head pressure– This is how far your pump can suck water up vertically. Your dam could be 6m deep and you throw a hose to the bottom of the dam out to your pump. You pump needs to have enough suction power to pull the water up 6m into the pump body.

OK, we have covered the basics. Now-

How to Choose The Right Water Pump

First determine what you want the pump to do and what environment it will be in. Do you have 240 volts to power the pump or will it be petrol powered? Will it be indoors or outdoors? Different water pumps have different features, and it is important to choose the pump with the features required to fulfill your task.

Here is a list of the popular applications for a water pump:

  • Dam or Flood Pump for moving clean or dirty water from your dam to the garden, crops, a tank or another dam
  • Sprinkler or irrigation pump
  • Submersible Utility Pump
  • Well pumps for bringing water from a well to your house
  • Booster Pumps for increasing water pressure within your home
  • Fountain or Water Feature Pumps
  • Fire Hose Pumps
  • Swimming Pool Pump

Portable 4 stroke Dam or Flood or Fire Pump– These are a very useful type of pump and are used to clear flood water, move water from one dam to another or to spread dam water around your property. These pumps are usually petrol-powered pumps as they can be a long way from an electric power point. And if a fire was in the area, you may not be able to rely on electricity.

You definitely need a self-priming pump with good suction as you are usually removing water from low ground to higher ground. Pumps are often rated with the suction head. You need to think about how deep your water source is and choose a pump that can suck uphill. If you have a 10m deep dam or well, you will need a pump with at least 10m suction height head pressure capability.

You then need to match the flow to the amount of water you want move.

Naturally, a pump with a larger inlet size such as 50-100mm and with a larger pump body and motor will move more water faster, then say a pump with a 25mm inlet. But we again need to think about the application. If you are emptying a small water tank then you probably only need a 25mm inlet, but if you want to empty a large dam, you will want a 50-100mm inlet with a larger water pump and flow capability.

Sprinkler or Irrigation Pump- These are a very popular type of pump and will typically be attached to mains water or to tank waster and they will boost pressure for sprinklers and watering systems over a larger property. One way to work out your requirements is to count the number of sprinkler heads you plan to use and check their recommended litre/hour rating and pressure requirements. If you had 20 sprinkler heads and they were rated at 3 litres per minute, then you would need a pump capable of pumping 60 litres per minute of 3,600 litres per hour.

You can also check the size of the area you wish to irrigate. An average garden can require 6-20 litres of water per m2 per day depending on the soil and the time of year. That means a 100m2 garden may require 600-1,000 litres of water per day. If you wanted to run your pump for 1 hour per day, then that is the volume you need to aim for.

Submersible Pumps

These are a clever design where the pump and the motor are encased in a waterproof casing and then the pump and motor are totally immersed in water. The pumps are usually very efficient as the push water rather than pull water. They use a spinning impeller and centrifugal force to push water out of the pump and pressurise the system. Submersible pumps are usually used for irrigation, pumping water from a well or bore and draining unwanted bodies of water.

Well Pumps

These are also usually a submersible pump. See Submersible pumps.

Booster Pumps

These clever pumps are specifically designed to boost the pressure of your hot water system. Many hot water systems use an older Gravity Fed Hot Water System, and these do not use mains pressure. They rely of a header tank in the roof cavity to provide pressure and this is often a problem when you are trying to take a nice hot shower. A booster pump can double the water pressure of these gravity fed hot water systems. The pump design is a circulation pump, and it is fitted with seals and bearings that can take up to 100°C temperatures. Some models are also designed with a flow switch so that the pump senses water flow and kicks into action. Then the pump turns off when the hot water tap is turned off.

Fountain or Water Feature Pumps

These are usually a very simple and low to medium flow rated pump that can create a fountain effect or pump water from a pond up to a higher level and create a small water fall effect. Flow rates can vary between 200 litres per hour up to a high of 1,600 litres per hour. The higher rated pumps can spray up to 3.0-4.0 meters.

These pumps are submersible and sit in the lowest part of your pond. The fountain spray is mounted on top or else a hose is attached to pump water up to a higher level.

These pumps are often solar powered and will not need a power supply. The basic versions will turn the flow off on cloudy days or at nights. More expensive models will have a battery back up and they will store power and keep your pump running on cloudy days. Other models also include LED lighting to light up the water fountain. Prices range from between $50-$300.

Fire Hose Pumps

These pumps are usually petrol-powered pumps as they can be a long way from an electric power point. And if a fire was in the area, you may not be able to rely on electricity.

You definitely need a self-priming pump with good suction as you are usually removing water from low ground to higher ground. (Most of these pumps will need a small amount of water added to the pump body to prime the pump before initial start up).

Pumps are often rated with the suction head. You need to think about how deep your water source is and choose a pump that can suck uphill. If you have a 10m deep dam or well, you will need a pump with at least 10m suction height head pressure capability.

You then need to match the flow to the amount of water you want move.

Swimming Pool Pumps

A correctly sized swimming pool pump is a vital part of any swimming pool. They keep the water circulating and push the water through a pump filter to keep the pool clean and sparkling.

The correct size pump will circulate the entire pool volume in 8-10 hours. If you have a 15,000 litres pool, you will need a pump that can circulate 2,000-3,000 litres per hour.

You should also choose a pool pump that suits your plumbing. If you have 1 ½” of 38mm pipe work, choose a pump that matches this size. Other pools often have 2” or 50mm pipe work.

Make sure you take into account the distance of the pump to the pool. The further the distance the more drag and the larger size pump may be required.