If a person has a problem that constantly breaks his wudu, such as one who suffers from urinary incontinence and constant wind and can not control it at any certain time of the day, he should do wudu at the time of each prayer, and then pray.
The scholars regarded the one who suffers urinary incontinence as coming under the same rulings as the woman who suffers from istihaadah (irregular non-menstrual bleeding).
Our mother ‘Aa’ishah reported:
Faatimah bint Abi Hubaysh came to the Prophet (peace and blessings of Allah be upon him) and said: “O Messenger of Allah, I am a woman who suffers from constant non-menstrual bleeding (istihaadah), and I never become pure. Should I give up prayer?”
The Messenger of Allah (peace and blessings of Allah be upon him) said, “No, rather that is from a vein, and it is not menstruation. When your regular time of menstruation comes, then stop praying, and when that time is over, then wash the blood off yourself and pray, then do wudu for every prayer until that time comes.” Narrated by al-Bukhaari, 226 – this version was narrated by him; and Muslim, 333.