A small town has an Underground Water storage tank.
But there is another big city of 10-11 Crore People, which has a Gutter/Drainage that passes right next to the town's Water tank.
What happens is that the Content from the gutter slips into the Tank and contaminates it. Most people of the town are not willing to acknowledge it since the Mayor of the big city does not want to re-locate the gutter.
Then overtime, people start to accept that the Tank's water taste bad by default.
They try to clean the Tank and pipes, but that does not help. Every time they clean it , it clears for a bit, but the dirt from the gutter keep contaminating the well. Since the source of the dirt isn't the well itself, cleaning the Tank does nothing.
The image of Tank is being tarnished by the gutter, visitors to that small town complain of the smell and taste, but the town folks can't explain it, they have to take the blame and accept the foul water as their own doing.
If the town folks want clean water, they must first create a barrier between the Tank and the gutter. If they can't do that, the water will always be contaminated and no matter how much cleaning of the tank they do, they can't get clean water, and they will be forced to live with it.
the first step of making sure the water is clean is differentiating between the gutter and water and not allowing the gutter to sneak in and represent itself as water.