1. Any discharge, no matter how small, from the front or back passage, such as urine, excrement, wind, Wadi (dense white post-urination fluid), Madhi (prostatic fluid), or Maniy (sexual fluid).
2. Deep sleep (as opposed to light sleep in a sitting or standing position that involves no loss of consciousness).
3. Absence of the mind due to insanity, fainting, drunkenness, intoxication, or medications that produce unconsciousness.
4. Touching the private parts (front or back passage) directly with the hand without a barrier.
5. Eating camel meat.
Factors that prevent the validity of ablution:
Presence of any physical barrier between the skin and water such as grease, wax, glue, nail polish, and similar substances that act as a screening layer and prevent water reaching the skin. This is because one of the essential conditions for Taharah to be valid is that the water must come in direct contact with the skin and fingernails.
Difficulty sustaining ablution:
People who have a condition that constantly invalidates their ablution, such as urinary or flatus incontinence or Istihadah (abnormal vaginal bleeding outside the menstrual or post-partum period), should perform ablution before every prayer.
