How should a patient who is in a constant state of hadas, such as one using a colostomy bag or continuous bladder drainage, perform the ritual bath for janabah?

Summary

Such a patient is regarded as able to use water, so the ritual bath is done by removing the bag containing waste, cleaning the stoma area where relevant, performing ablution as usual and pouring water over the whole body. After this the patient may pray, and if waste leaves the body during prayer, the prayer remains valid because it is excused due to hardship and necessity, and need not be repeated after recovery. The fatwa also permits such a patient to combine Zuhur with Asar or Maghrib with Isyak, either as jama' takdim or ta'khir, or in the form of a outward combination. Shortening prayers (qasar) is not covered by this allowance.

Written in our own words from the original fatwa — check the source before acting on it.