Yes, in many Jain traditions, boiled water kept for the same day for ayambil is generally acceptable, if it is handled according to your vrata/practice rules.

Important points:

• The water should be boiled properly.
• It should be stored in a clean, covered vessel.
• It should be used the same day, as per the usual ayambil discipline.
• Some traditions or local practices may be stricter about storage method, vessel, or timing.

For the safest Jain observance, follow the guidance of your guru, sthanak, or local tradition. If your practice is very strict, many people prefer to keep the boiled water in a clean, dedicated vessel and avoid any contamination.

If you want, I can also explain the usual ayambil water rules in simple Jain terms.