Nullifiers of Ablution According to the Hanafi school
It is stated in Gifts of Guidance (‘al-Hadiyya al-`Ala’iyya), of Allama Ala’ al-Din Abidin:
Ritual ablution (wudu) is nullified by:
1. Anything that exits from the private parts, even if it not customary such as a worm or stones.
2. The flowing of any ritually impure substance (f: such as blood or pus) from a wound (f: or other opening) to any place that requires cleaning (f: i.e. it flowed beyond its point of exit), or if it came out with enough force to flow (f: but was prevent from flowing because it was wiped or absorbed by a bandage).
3. Vomit that is a mouthful, such that one would not have been able to keep it in without difficulty, except if it is just phlegm. Vomit that is from the same motion (ghathayan) is considered together when determining whether it is a mouthful or not.
4. Blood (B: from the mouth or throat) that overcomes one’s saliva or equals it (f: if closer to red, wudu is invalidated; if closer to yellow, it is not).
5. The sleep of one whose rear is not firmly seated. As for the one whose rear is firmly seated, his ablution is not nullified by sleep, even if leaning against something in a way that if it were removed he would fall.
6. Loss of consciousness.
9. The laughter of an aware adult person a prayer that contains bowing and prostration, even for the one praying by head motions alone. If the laughter occurs after the tashahhud, the ablution is nullified, though not the prayer. If you laugh such that only you could hear it, then it does not invalidate your wudu but does invalidate your prayer.
10. (Direct contact between an erect penis and the vagina of a desirable woman.