Most homeowners who are considering the option of installing a water tank system either harvest rainwater or to supplement the often-interrupted municipal water supply, battle with the question as to what size tank they will need.

This would depend on a variety of factors such as:

• How many people are using water in the home daily?
• What aspects of the running of the home can/will the water be used for?
• How often would the tank be called into use?
• How many days/weeks would the household usually need to rely on the alternate water supply from the tank?
• How easy is it to replenish the tank if all the water has been used?

How to replenish the tank

Your water tank can be replenished from the existing municipal supply by connecting your tank to the existing municipal system, with a cut off valve to stop the flow to the tank once it is full. It the system is relying on rainwater harvested from a suitable rooftop, then calculations and predictions become a bit