[Machine] It was narrated from the Prophet ﷺ that he used to wash his head with khitanmi while in a state of junub (sexual impurity), using a small amount of water so it wouldn't pour over him. If this has been confirmed, it is permissible if water was generally available to wash his head with khitanmi. He used to wash his head as part of purifying himself from janabah (sexual impurity), and likewise.  

عَنِ النَّبِيِّ ﷺ أَنَّهُ كَانَ يَغْسِلُ رَأْسَهُ بِالْخِطْمِيِّ وَهُوَ جُنُبٌ يَجْتَزِئُ بِذَلِكَ وَلَا يَصُبُّ عَلَيْهِ الْمَاءَ وَهَذَا إِنْ ثَبَتَ فَمَحْمُولٌ عَلَى مَا لَوْ كَانَ الْمَاءُ غَالِبًا عَلَى الْخِطْمِيِّ وَكَانَ غَسْلُ رَأْسِهِ بِنِيَّةِ الطَّهَارَةِ مِنَ الْجَنَابَةِ وَكَذَلِكَ