If a dead mouse is found in a well and it has NOT swollen or decayed, and the time of death is unknown, when is the water declared impure?

Well Purification: Moderate Drainage & Unknown Decay Timings

• From 3 days and 3 nights ago.
• From 1 day and 1 night (24 hours) ago.
• Only from the exact moment of discovery.
• From 10 days ago.