INSTRUCTIONS ABOUT ISTINJA (From Bahishti Zewar)
(1) Whatever impurity is excreted either from the front or back makes it imperative to cleanse the affected part i.e. to perform ISTINJA.
(2) If the impurity has not spread on the sides of the affected part and water is either not available at all or is not sufficient for ISTINJA, then it is permissible to wipe the affected part clean with stones or earth until all the impurity has been removed and the body
has become free from it. However, being repugnant to be the basic idea of cleanliness and purity this method should be resorted to only in extreme circumstances. [Tanwir-Shami]