Now basti: seated in utkaṭāsana in water up to the navel, with a tube inserted in the anus, contracting the sphincter, thus one should practice basti.

This verse describes jala basti, the cleansing of the colon with water. The practitioner sits in utkaṭāsana (squatting posture) in water reaching the navel (nābhidaghna). A hollow tube (nāla) is inserted into the pāyu (anus).

The technique consists of ādhāraṃ kuñcayet — contracting the anal sphincter. Through nauli (abdominal churning) and muscular control, a vacuum is created that draws water into the colon. The water is then expelled along with impurities.

This is a form of natural enema that requires no external pressure. The ability to absorb water through muscular control is a minor but significant siddhi. The practice cleanses the colon of accumulated residue, parasites, and toxins, improving both physical health and the capacity to retain prāṇa in advanced practices.