1. The color of your tank, and
2. How often you pump water into the tank from your borehole.

Before we go further into these two factors, here’s something you may not know about your water storage tank: it begins to get dirty (with mostly sand and bacteria) as soon as it starts to receive water from your borehole.

Borehole water often contains particles – sand in particular – and even if you filter the sand, the sunlight that hits your water tank promotes the growth of microorganisms – typically bacteria your eyes cannot see – that still contaminate the water.

Furthermore, if like many Nigerians you don’t drink directly from your borehole/storage tank, the contaminated water can still make you sick because you brush your teeth with it, shower with it, and cook with it.

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