I don't quite understand the Lord water purification and other details around that

I always include relevant wiki links for that reason, it needs a little extra time to go through them to understand. First there is a bathe festival, and then the Lord falls sick in fever because of that - like us. Then he is treated in a closed room - again like us, as we don't go out or meet anyone when we fall sick. And once recovered, he travels to meet the world.

Hope it gives a little context. The short one is where we participated, the live feed is from Puri, where millions of people have gathered to meet the Lord.