Acamana - Sipping Water for Purification

Acamana, or sipping water, is a means of purification. As immersing the body in water brings about physical and subtle cleansing, so taking water infused with mantras into the body by sipping performs a similar function. Thus where purification is required but it is inconvenient to bathe, acamana is prescribed.

The general process of acamana is as follows: While looking into water cupped in your right hand, chant a mantra directed into that water and then sip the water. A devotee should perform acamana to achieve physical and mental purity before performing spiritual activities such as

1. applying tilaka, 
2. chanting Gayatri and japa, 
3. performing puja and homa, 
4. observing a vrata, 
5. taking prasada, 
6. reading or reciting sastra or mantras, and 
7. meditating. 

The place where a devotee performs acamana should be pure – i.e., free from hair, bones, ash, or any other impure item. The water should be cool, fresh, without bubbles or foul odor or taste, and untouched by fingernails, hair, or any impure item. Rainwater, being in the mode of passion, should not be used. Out of respect for a spiritual activity, do not perform acamana with your head or throat covered; without having your kaupina or cloth tucked in at the back; without first cleaning your hands and feet; with shoes on; while standing; or while sitting on shoes or sitting with your knees or feet showing.
Mantra
http://www.iskcondesiretree.net/page/acamana-sipping-water-for

Reference
http://www.vedabase.net/a/acamana

Tube
https://www.youtube.com/results?search_query=ACHAMANA