According to Jainism, the principle of ahimsa (non-violence) is of utmost importance. Jains strive to minimize harm to all living beings, including the tiniest forms of life such as microorganisms found in water. Drinking unboiled water can lead to the ingestion and destruction of countless microscopic life forms.

By boiling water and then filtering it, many of these microorganisms are either removed or rendered inactive, thus reducing the number of living beings harmed when consuming the water. While boiling does kill some microorganisms, Jain scriptures and tradition teach that it is better to minimize harm as much as possible, rather than causing harm unknowingly by consuming raw water full of life forms.

It is also prescribed in Jain monastic codes (like the Acharanga Sutra) that monks and nuns should drink only boiled and filtered water, and householders are also encouraged to do the same, especially during the rainy season when waterborne life is abundant.

In summary, Jains drink boiled water not with the intention of killing germs, but rather to reduce the number of living beings harmed while fulfilling a basic necessity, thus practicing ahimsa to the greatest possible extent.