Kumbha Sthaapanam is the ritual for invoking and worshiping Lord Varuna in the sacred Kumbha (water pot). For these purposes, a water pot made of silver, gold, copper, brass, bell metal or clay is decorated with strings and placed on a pile of raw rice. Into the pot, water, rose water, and ganga jal are added along with herbs: cardmom, clove, nutmeg, vettiver, sandalwod, tulsi, agar, saffron, priangu, and edible camphor. Into this a buble of 16 kurchas of darbha grass is placed. And then five mango leaves are placed with a coconut painted yellow with turmeric paste placed on top. Vastram and flower garland is used to decorate the kumbha and then the Lord is invoked there for worship. This text shares a pancha puja making five offerings, relating to the pancha maha bhutas (five elements), but Shodasha puja could also be offered. A water pot is traditionally placed before any homam to temper the fiery energies of the fire rituals. The water gets blessed through puja and homam and is energized for consecrating and energizing a murti (sacred image of God). This water is also used to sprinkle over the devotees (prokshanam) which bestows blessings - or to purify a house as in vastu shanti or to purify a temple as in punyahavachanam.
We have a short Kumbha Staapanam text, included below in Sanskrit and English, based on the Apastambha Sutra.