You can boil water today and use it tomorrow, but within Jain maryada there are some limits:

1. General Jain rule for boiled water (ukālelā pānī / garam pāni)

- Normal days (excluding Chaturmas): Boiled water can usually be used up to 48 hours from the time of boiling, if it is kept covered and clean. - During Chaturmas / monsoon: Many follow a stricter rule of 24 hours only.

1. For more strict practice (closer to sadhu–sadhvi rules)

- Some follow only 24 hours all year, or even less during Chaturmas. - Digambar maryada is often stricter; many prefer freshly boiled water more frequently.

1. So for your question “today boil water kal”:

- If you boil water today in the daytime, it is generally allowed to drink it tomorrow (kal), provided: - Total time from boiling is within 24–48 hours as per your tradition. - It is kept well‑covered, clean, and untouched by insects/dust. - During Paryushan / Chaturmas, try to keep it within 24 hours.

If you want detailed explanation of “ukalela pani no kal” and “how long boiled water can be used”, you can read more here and here