Prathamopadeśaḥ (Ṣaṭkarma) · Verse 19
बस्तिस्तु द्विविधा प्रोक्ता जले खेचर्यां तथैव च | जलबस्तिस्तु कर्तव्य उदराम्बुजवत्स्वके ||
bastistu dvividhā proktā jale khecaryāṃ tathaiva ca | jalabastistu kartavya udarambujavatsvake ||
The detailed description of basti, the yogic enema, begins. Jala basti is practiced submerged in water up to the navel (udara-ambu), which aids relaxation and facilitates the technique.
Water acts as a medium of support and hydrostatic pressure. Submerged to the navel, the external water balances internal pressure, allowing the colon to fill and empty with greater ease.
This is one of the most advanced techniques of the ṣaṭkarmas and requires personal instruction.