Padodaka is the water poured onto Ishtalinga and collected one. Pādodaka is holy water. It’s prepared from bathing the Ishtalinga or Guru 's feet. It is one of the Ashtavarana or the 'eight protections' of Lingayat Religion.
This holy water is used in many sacred occasions to call upon good fortune and celestial blessing. It is sprinkled across while entering into a new house, on the newly bought vehicle etc.
Water is the most important of the five elements from the point of view of cleanliness. The Padodaka is the symbol of the washing of three (the three taints Anavamala = inferior taint (feeling having bound with god, self limitation, Mayamala = illusory taint and Karmikamala = Physical taint) taints attached to the soul. Guru and the Jangama being Jivanmuktas are free from all taints. And their Padodaka is the embodiment of the taints. The devotee has to be free from the taints attached to his soul and takes a lesson from the Padodaka that he has also to strive to be free from the three taints, when he takes the Padodaka of his Guru or Jangama .
The Padodaka is thus intended to produce a psychological effect on the devotee that he should wash his soul clean of the three taints, as he has to wash his body clean of all physical dirt. The exercise for making the devotee aware of the three taints and the necessary of washing them away from the soul gradually by cultivating merely ordinary water called teertha. It is the symbol of the water of knowledge (Jnanajal) that washes away the taints that stick to and constrict to the soul.
 From the book "Vachana", pub: Basava Samiti Bangalore 2012.