The short answer is that it depends on these two factors:
- The color of your tank, and
- 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.
Sand from a Water Storage Tank.
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.