FEATURES 19
1 . Flow Rate This determines how quickly the pump can deliver water . Take a look at the water demands and choose a pump with a flow rate that matches that demand . Compare peak demand and average use to make sure that the pump can handle the water volume .
2 . Power and Pressure The required pressure or Total Dynamic Head TDH ) is as important as flow rate . For instance , if you have a below-ground installation and need to pump to the sixth floor of a building , you need enough TDH to push the water up to compensate for the difference in the height . If you don ’ t do that , the water is not going to get to that part of the building .
Talk to your client about what they want to use the water for because different applications need different kinds of water pressure . Irrigation will need something quite different from a building reticulation application , so keep this in mind . At the same time , look at the power source for the pump - whether electricity , manual or solar - and find a pump that would work best with that power source .
To get the right kind of pressure to align with a regular residential system , you ’ ll need a pump that can produce 45-60 psi .
3 . Size and Capacity Take note of the space you have to fit the pump and make sure that your pump actually fits . Remember also to take the pump ’ s capacity into account when it comes to the maximum amount of water it can handle .
4 . Efficiency Perhaps it goes without saying but look at pumps that have high energy efficiency ratings . This ultimately saves your client costs and
Common problems with pumps :
• Lack of maintenance – this can cause valve leakage or blockage . For example , the non-return valve , gate valve , y-strainer , ball valve etc
• Incorrect operation can cause clogging , wear , corrosion , overload and material fatigue
• Sizing the pumps for the right applications
• Installation and commissioning
How to fix it :
• Prevent debris from entering rainwater collection systems
• Install the correct size for the correct application will have a positive effect on the rainwater harvesting system ’ s performance .
5 . Durability Here you will need to look at corrosion-resistant materials like stainless steel . Your pump needs to be able to handle exposure to rainwater and all kinds of weather conditions . This means fewer maintenance calls , but durability and reliability .
6 . Technology There are some pumps on the market that come with some cool features like adjustable speed settings or automations . This is great for customising a pump ’ s use according to what the client needs . Automation is a bonus as this lets your client enjoy the peace of mind that the pump is doing what it needs to , and they don ’ t have to do much except use the water they are collecting .
7 . Power To obtain higher flow rates and pressure , one might need pumps with bigger kilowatts . Typical domestic applications usually only work with available 1Ph 230V which vary from as little as 370 watts up to 2 200 watts and for commercial applications , one typically finds 3Ph 380V which typically use up to 45KWs or greater if necessary .
8 . Check for a Warranty Make sure there is a decent warranty in place on the pumps so that you and your client are protected against any possible defects . Aftersales and technical support are big pluses if it comes down to trouble shooting .
While budget is a consideration for many households , with a rainwater system that will be in place for many years , it may mean spending a little more for a durable and reliable pump . PA
• Install screens or filters
• Regular maintenance to the pump and system
Flow rates
• Garden Hose : 9 to 18 litres per minute
• Toilets : 7 to 9 litres per flush
• Washing Machine : 9 litres per minute
" To obtain higher flow rates and pressure , one might need pumps with bigger kilowatts "
February 2025 Volume 30 I Number 12 www . plumbingafrica . co . za