Purity: Continuous Incontinence Without Respite
Practical Laws of Islam as per the teachings of Ayatullah Sistani
Ruling 308:
If urine or faeces is discharged with such frequency that the person does not find a long enough respite to perform wuḍūʾ and part of the prayer, then one wuḍūʾ will be sufficient for several prayers unless he does something else that invalidates his wuḍūʾ – such as urinating or defecating in a normal manner, or sleeping – although it is better that he perform wuḍūʾ for every prayer. However, for a lapsed (qaḍāʾ) prostration (sajdah), a qaḍāʾ tashahhud (testifying), and the precautionary prayer (ṣalāt al‑iḥtiyāṭ), performing another wuḍūʾ is not necessary.
-Ayatullah Sistani, Practical Laws of Islam, Purification (Taharah)