Bring water to a gentle boil in a non-reactive pot or pan.
Optional: Crush the cumin seeds with a rolling pin or in a mortar pestle. The idea here is to release their flavor and volatile oils. You don't need to make a fine powder.
Add them to the water and bring it to a boil on a medium heat.
Then reduce the flame and simmer for 5 minutes. Bring this to a boil again on a slightly higher heat and turn off.
Cover and let cool down until warm.
Place a strainer over a cup or a pitcher. Filter jeera water and serve warm or at room temperature.
If you prefer to make a larger batch of jeera water for the day, boil 10 grams of cumin seeds in 1250 ml of water following the same steps mentioned above. Strain and enjoy it.