In Jainism, the principle of ahimsa (non-violence) is of utmost importance, and it extends to all living beings, including microscopic organisms such as germs in water. According to Jain teachings, ideally, one should avoid harming even the smallest forms of life. For this reason, traditionally, Jains use a cloth filter (such as a mulpatti or chhanni) to strain water before drinking, thereby reducing the number of micro-organisms ingested and minimizing violence.

Boiling water does indeed kill germs, which is a form of violence against living beings. However, some Jain traditions permit boiling water for health and hygiene, especially during the rainy season (chaturmas), when the number of micro-organisms in water increases. This is allowed as a pragmatic compromise to protect the human body from disease and to maintain health, which is necessary for spiritual progress. Even then, the water is typically filtered after boiling to remove dead organisms.

Some stricter sects, like the Sthanakvasi and Terapanthi Shwetambaras, and many Digambaras, prefer only filtering water and avoid boiling, to minimize himsa.

In summary:

• The ideal practice is to filter water to avoid killing germs.
• Boiling water is sometimes allowed for health, but it is seen as a necessary exception, not the ideal.
• The intent is always to minimize violence to all forms of life as much as possible.

Thus, Jainism teaches to minimize harm rather than eliminate it entirely, acknowledging practical necessities but always striving for the highest standard of non-violence.