The Ritual Bath
Nīrāttam (Tamil: nīr = water + āttam = pouring/bathing; 'the pouring of water') refers both to the abhiṣeka (ritual bathing) of the deity and to the devotee's own prescribed ritual bathing (snānam) as part of the daily nityānuṣṭhānam.
Deity Abhiṣeka
At major temples, the deity (specifically the utsavar, as the mūlavar is bathed according to special Āgamic procedures) is bathed during tirumanjanam ceremonies with a sequence of liquids: water, milk, coconut water, honey, sugarcane juice, pancāmṛtam, and again pure water — each accompanied by specific mantras. The water that flows from the deity's body after bathing becomes the supremely sacred theertham distributed to devotees.
Devotee's Bathing
The devotee's morning bathing (snānam) before worship is not merely hygienic but ritual purification — traditionally performed in a flowing river, temple tank, or with well water, accompanied by appropriate mantras. This bathing prepares the body as a fit instrument for the day's worship.