Praise be to Allaah.
The person who is suffering from incontinence should make a new and separate wudoo for each prayer when the time comes, even if he has just made wudoo for another prayer a short time before. This is because the Prophet taught the woman who suffers from istihaadah (prolonged non-menstrual vaginal bleeding) to do this. Aaishah said: Faatimah bint Abi Hubaysh came to the Prophet (peace and blessings of Allaah be upon him) and said: O Messenger of Allaah, I am a woman who experiences istihaadah and I do not become clean from bleeding. Should I forget about salaah? He said: No, that is from a vein; it is not menses. When your period starts, then stop praying, and when it ends, wash the blood from your body and pray again. Abu Muaawiyah said in his hadeeth: He said: Do wudoo for each prayer, until the time for the next prayer comes Abu Eesaa said: The hadeeth of Aaishah is a saheeh hasan hadeeth, and this is the opinion of more than one scholar among the Companions of the Prophet (peace and blessings of Allaah be upon him) and the Taabieen. It is also the opinion of Sufyaan al-Thawri, Maalik, Ibn al-Mubaarak and al-Shaafii that when the woman who suffers from istihaadah finishes her regular period, she should do ghusl, then do wudoo for each prayer.(Sunan al-Tirmidhi, 116; the hadeeth was reported by al-Bukhaari, no. 221).
Ibn Hajar (may Allaah have mercy on him) said: The ruling on non-menstrual blood (istihaadah) is the same as the ruling on anything that breaks wudoo: she should do wudoo for each prayer, but she should not pray more than one fard prayer with that wudoo, whether she is praying on time or is making up the prayer later, because of the apparent meaning of the hadeeth, You should do wudoo for each prayer. This is the opinion of the majority of scholars.(Fath al-Baari, Kitaab al-hayd, Bab al-istihaadah). The same ruling applies to the person who suffers from continual incontinence or wind. You can pray as many naafil prayers as you like with the wudoo you made for a fard prayer, until the time for that fard prayer is over. And Allaah knows best.
Sheikh Muhammed Salih Al-Munajjid