Achamanam

“Achamanam” . Achamanam is a purification ritual. 

There are three types of Achamanam i.e. Shrauthaachamanam, Smrutaachamanam (or) Smaarthaachamanam and Puranaachamanam. In most of the variations , individual sips water three times and recite purification mantras.  Irrespective of mantra (or) ritual, But most important key words here are “water” and “purification”, both internal and external but mostly internal/spiritual.

Water

Please See blog for relevance of water 

Purification

One should be pure both mentally and physically before any ceremonial worship of God or his attendants. By sipping water, itself a form of Narayana, one purifies the mouth and heart before one chants His praises. By reciting His Name while doing so, one centers his mind on God; the mind thereby discards its naturally lustful, angry, and greedy condition, making itself ready to bow before the Supreme.

So it is with these thoughts and intentions that Achamanam is done before beginning any holy work.

When it is done

Achamana is done before doing any holy work. However, achamana is not done before taking teertha and prasada because these are holy and pure which will purify a person directly on consumption. There is no need of achamana to be performed in such cases. The basic purpose of doing achamana is to become physically and mentally clean.

How to perform

Purana Achamanam

Achaman is mainly divided into two parts 1. taking 3 sips of water and wiping twice i.e. Unmarjana and reciting kesava naamas. Though largely 3 sips and kesava naama is common, not all say same names refer Various Practices section for different 

Touch water pot with left hand as in the left hand reside the twelve Adithyas as well as Varuna the lord of water. Then take spoonful of water into right hand palm and to recite “Kesavaaya Swaaha” and sip it with the Palm tipped back slightly from the base of the thumb in the name of Lord Kesava. Repeat this act reciting the “Narayanaya Swaaha” in the name of Lord Narayana. Again repeat this act for the third time reciting “Madhavaya Swaaha” in the name of Lord Madhava.

Perform the above act by reciting the 21 names of Lord Vishnu called Kesava Naamaas by touching various sensory organs and other parts of the body

Kesava Naama

Following are the 24 names of kesava. First 5 are recited during sipping of water to remove tapatriya.

Based on Vadiraja Thirtha composed Chaturvimshati Moorthi Bedha Stotra all 24 forms hold 4 emblems in 4 hands i.e. Shanka, Chakra, Gadha and Padma. But order in which emblem held in hands change based on lord's name 

Similarly all 24 forms are associated with various water bodies except vasudevaadi 4 roopas. 

It is also said that these 24 names also represents 24 letters of Gayathri Manthra called Beejaksharas that have influence on the human body.

No.	Lord’s Name	Procedure during Achamanam	Lakshmi’s Name	Abhimani Devatha	Neivedya	Color of Lord	Tattvas (Elements)	Elemental Category	Chaturvimshati Emblem Order (Right Up,Left Up, Left Down, Right Down)	Water Body	Gayatri
1	Keshava	Sip water	Sri	ramA	anna / Chandra	Gold (Yellow)	Avyaktha	Antah Karana	Shanka, Chakra, Gadha, Padma	Pinakini	ta
2	Narayana	Sip water	Lakshmi	brahma, vayu, sarawathi, bharati	pramanna / Bharati	White	Mahatatva		Padma, Gadha, Chakra, Shanka	Godavari	Tsa
3	Madhava	Sip water	Kamala	garuda, Shesha, rudra, sauparNi, vAruNi, pArvati	bhakshya / Surya	Black	Ahankara		Chakra, Shanka, Padma, Gadha	Ganga	vi
4	Govinda	Clean Hand	Padma	indra, kAma	Ghee / Lakshmi	Spatika (Crystal white)	Manotatvam		Gadha, Padma, Shanka, Chakra	Vapi	tuH
5	Vishnu	Clean Hand	Padmini	dhikdevatas iMdra , AgnEya(SE):Agni , daxiNa(S):yama , nairutya(SW):niruRiti, pashchima(W):varuNa, vAyuvya(NW):pravahavAyu, uttara(N):kubEra, IshAnyA(NE):Rudra	Milk / Saraswathi	Padma Kesar (Yellow)	Shrotha (Ear)	Pancha Gnanendriya	Padma, Shanka, Chakra, Gadha	Narmada	va
6	Madhusudhana	Clean Upper Lip	Kamalalaya	ahaMkArika prANA	Mandigey / Brahma	Red	Mridula Tyak (Core Skin)		Shanka, Padma, Gadha, Chakra	Manasa	re
7	Trivikrama	Clean Lower Lip	Rama	Surya	Butter / Vayu	Fire (Red)	Chakshus (eyes)		Gadha, Chakra, Shanka, Padma	Kamudavathi	Ni
8	Vamana	Sprinkle on head	Vrushaakapi	varuNa	curd / varuNa	Rising Sun (Red)	Jihve (Tongue)		Chakra, Gadha, Padma, Shanka	Chandrapushkarani	yam
9	Sridhara	Sprinkle on head	Dhanya	Ashwini	Bele / Garuda	White	grahANa (Nose)		Chakra, Gadha, Shanka, Padma	Bhimarathi	bha
10	Hrishikesha	Sprinkle on Left Hand palm	Vruddhi	agni	Green Leaves / Mitra	Lightning (White)	vadana / vAK (mouth)	Pancha Karma Indriyas	Chakra, Padma, Shanka, Gadha	Sarovara	rgo
11	Padmanabha	Sprinkle on Feet	Yagna	daksha Prajapathi	Vegatables / Sesha	Black	pANendriya (hand)		Padma, Chakra, Gadha, Shanka	Saraswathi	de
12	Damodhara	Sprinkle on head	Indira	jayantha (Indra son)	Amla (Sour) / Gowri	Red	pAda (leg)		Shanka, Gadha, Chakra, Padma	Saritha	va
13	Sankarshana	Touch Chin	Hiranya	mitrAkhyasUrya	Huli / Rudra	Red	Payu Sthana (Excretory Organ)		Shanka, Padma,Chakra, Gadha	-	Sya
14	Vasudeva	Touch one nostril with right thumb and first finger	Harani	swayambhu manu	Sugar (or) Jaggery / Indra	White	upastha (reproductory Organs)		Shanka, Chakra, Padma, Gadha	-	DhI
15	Pradyumna	Touch another nostril with right thumb and first finger	Sathya	brahaspati	Chatni (or) Seasoning (or) Flavour / Bruhaspathi	Gold (Yellow)	shabdha (Sound)	Pancha Tanmatras (or) Pancha Vishays (or) Pancha Prana	Shanka, Gadha, Padma, Chakra	-	Ma
16	Anirudha	Touch left eye with left thumb	Nitya	apAna	Bitter / Yama	Black	Sparsha (touch)		Gadha, Shanka, Padma, Chakra	-	Hi
17	Purushothama	Touch right eye with ring finger (anamika)	Nanda	vyAna	asatofoedia (or) cardomom (or) mustard (or) kesari jeera / Manmatha	Spatika (Crystal White)	rUpa (form / Sight / Light)		Padma, Gadha, Shanka, Chakra	Pushkarani	Dhi
18	Adokshaja	Touch left ear	Treya	udAna	Fried Items / Jayantha	Black	Rasa (Taste / liquid)		Gadha, Shanka, Chakra, Padma	Swami Pushkarani	Yo
19	Narashima	Touch right ear	Sukha	samana	sesame or pumpkin / Daksha	Gold (Yellow)	Gandha (smell)		Padma, Gadha, Shanka, Chakra	BhavaNashani	Yo
20	Achyuta	Touch belly button with right thumb and little finger	Sugandha	mahaganapathi	black gram / Swayambhu manu	Yellow	Akasha (Sky / Space)	Pancha Bhootha	Padma, Chakra, Shanka, Gadha	Tataka	naH
21	Janardhana	Touch heart with palm	Sundari	pravahavAyu	Salt / Nirruthi	Red	Vayu (Air / Gas)		Chakra, Shanka, Gadha, Padma	Malahari	pra
22	Upendra	Touch head	Vidya	agni	AhankArika prana / Upendra	Black	Tejas (or) Vahini (Fire / Light)		Gadha, Chakra, Padma, Shanka	Devakatha	cho
23	Hari	Touch left shoulder	Sushila	varuNa		Yellow	Apa (Water)		Chakra, Padma, Gadha, Shanka	Kalindi	da
24	Krishna	Touch right shoulder with finger i.e. folded together	Sulakshana	dharAdEvi , Shanaishvara	Swadoodaka (molasses or syrup) / Budha	Black	Prithvi (Earth)		Gadha, Padma, Chakra, Shanka	Krishnaveni	yAth

Srauthaachamanam

Do achamanam i.e. three times sipping water while reading   following mantra (This is part of apah suktam)

आपो हि ष्ठा मयोभुवस्था न ऊर्जे दधातन

Aapo Hi Sthaa Mayo-Bhuvasthaa Na Urje Dadhaatana

Wash hands while reciting this

1.1: O Water, because of your presence, the Atmosphere is so refreshing, and imparts us with vigour and strength.

महे रणाथ चक्षसे 
Mahe Rannaatha Cakssase ||1||

Clean lips using thumb 

1.2: We revere you who gladdens us by your Pure essence.

यो वः शिवतमो रसस्तस्य भाजयतेह नः ।

Yo Vah Shivatamo Rasas-Tasya Bhaajayate-Ha Nah |
उशतीरिव मातरः
Ushatiiriva Maatarah ||2||

Sprinkle water twice over head

2.1: O Water, this auspicious Sap of yours, please share with us,

2.2: Like a Mother desiring (to share her best possession with her children).

तस्मा अरं गमाम वो यस्य क्षयाय जिन्वथ ।

Tasmaa Aram Gamaama Vo Yasya Kssayaaya Jinvatha |

Sprinkle water over left hand using right hand

आपो जनयथा च नः ॥३॥

Aapo Janayathaa Ca Nah ||3||

Sprinkle water over head

3.1: O Water, when your invigorating essence goes to one affected by weakness, it enlivens him,

3.2: O Water, you are the source of our lives.

Om Bhuuh
Touch chin with fingers
Physical Plane, Consciousness of the Physical Plane

Om Bhuvah, Oogumh Svah
Touch end of nose using thumb and fore finger
Antariksha or Intermediate Space, Consciousness of the Prana
Swarga, Heaven, Consciousness of the beginning of the Divine Mind

Om Mahah Om Janah 
Touch eyes with thumb and ring finger
Great, Mighty, Still subtler Plane felt as All-Pervading Consciousness
Generating, Still subtler Plane felt as All-Creating Consciousness

Om Tapah, Oogumh SatyamTouch ears with thumb and ring finger
Filled with Tejas, Still subtler Plane felt as filled with Divine Tejas or Illumination of Shakti
Absolute Truth, Most subtle Plane merging with the Consciousness of Brahman

Om Tat-Savitur-Varennyam 
Touch belly button with thumb and little finger
Bhargo Devasya Dhiimahi
Touch heart with hand
on that Savitur (Divine Illumination) which is most Adorable (Varenyam) and which is of the nature of Divine Effulgence (Bhargo Devasya), I meditate

Dhiyo Yo Nah Pracodayaat |Touch head with hand
May that Divine Intelligence (Dhiyah) Awaken (Pracodyat) our (Spiritual Consciousness)

Om Aapo Jyotii Raso[a-A]mrtam Brahma Bhuur-Bhuvah Svar-Om ||
Touch both shoulders (first right and then left)

Om, that Divine Consciousness which is:
Apah (All-Pervading),
Jyoti (Divine Effulgence),
Rasa (Divine Essence),
Amritam (Immortal and Nectar-like Blissful),
Brahma (Sacchidananda Brahman ) 

Smartha Achamanam or Smruthaachamana

This Achamanam is described in the TaittirIya AraNyaka ( 2nd Prasna, 15th panchati) . It is laid out by manu, yajnavalka

Trirachameth (Sip water three times)
DviParimujja  (Clean lips twice with thumb)
Sakruthu Upaspushya (touch lips with first finger, middle finger, ring finger )
thasavyam panim, (clean both hands with each other)
padav, (sprinkle water on legs)
prokshathi sirah: ( sprinkle water on head)
Chakshushi (touch eyes)
Nasike (touch nose)
Srothre (touch both ears)
hrudaya malabya. adhaapa Upasruseth : (touch heart with palm)

Place and posture

Aachamana should be done using Brahma theertha which is not hot. Before Achamana, For getting clean we should bathe in water reaching up to the chest in case of Brahmins, reaching up to the neck in case of Kshatriya, reaching up to the mouth in case of Vysyas and reaching up to the bottom of the mouth in case of Shudhras and ladies.

Sit facing the East or North direction in Padma or Swastika asana. Do not stand while performing Aachamanam. Alternatively Sit in the Kukkutasana (hen-like posture) with the soles of your feet firmly planted on the ground, the hands between the knees

The right hand should be held so that the forefinger, middle finger and ring finger are together and slightly bent upwards, while the little finger and the thumb are separated from the other three fingers. Take sip without making noise.

When not to do 

1. Aachamanam should not be performed in a standing position
2. Aachamanam should not be performed facing west or south
3. Aachamanam should not be performed with impure water
4. It should not be performed while being busy in other activities.
5. One should not wear Pavithra while performing Aachamanam.
6. Immediately after consuming prasada or sipping theertha.
7. With upper cloth worn on one side of the body or with cloth hiding the shoulders
8. Without sacred thread
9. With Dirty clothes
10. With untide hair
11. According to Markandeya Purana, Achamana not required After eating mango, sugar cane piece, betel leaf and Soma Pana

Why three sips

It is believed to free an individual performing the ritual from three shortcomings namely Kayik (physical/bodily); Vachik (verbal) and Manasik (mental). Even in the temple priest offers theertha (sacred water) three times as number three is believed to be auspicious. This number signify the Tridevata (Brahma, Vishnu and Maheswara), these deities also represent the three Gunas Rajasa, Sattwa, and Thamasa. They also represents tapatriyas. 
The physical benefits this ritual offers is that when you sip water thrice, your throat is cleared from Vata(air element) which is associated to Vishuddha Chakra,  Pitta(fire element) which is associated to Manipura Chakra and Kapha which is associated to Swadhisthana Chakra (water and earth element) doshas

Why touching lips,eyes, head etc

Wiping the lips is said to please river Goddess Ganga and Goddess Yamuna; Lord Surya and Lord Chandra are pleased if eyes are touched with water. Similarly Aswini Devathas are pleased by touching the nose, Fire and Wind Gods are pleased if we touch the ears with water. Paramatma (Almighty) by touching the head.

Reference in Puranas

Padma Purana

As the churning started, innumerable of the proud Danavas who opted for the head of thousand faced Vasuki out of pride got perished due to the poisonous flames where as Devas were at the tail end. Eventally, a massive ‘Halahala’ or the sky-rocketing poisonous flames engulfed the Univerese and by the grace of Three Names of Lord Vishnu viz. Om Achyutaya Namah, Om Anantaya Namah and Om Govindaya Namah, Bhagavan Shankara gulped the blue poisonous flames in his throat thus giving him the epithet of Neela Kantha. By the power of the three names of Vishnu, there would never be any hardship faced

Achyutaananta Govinda iti naamatrayam Maha Mantram hareh/ yo japetpriyato Bhaktaayaa Pranavaadhyam namontakam/ Tasya Mrityu bhayam naasti visharogaagnijam mahat/ Naamatrayam Maha Mantramjapedyam prayatatmavaan/ Kaala Mrityu bhayam chaapi tasya naasti kimanyatah

(Whoever recites the Three Names viz. Om Achyutaaya, Om Anantaaya, and Om Govindaaya sincerely and with dedication, none of the poisonous diseases or Agni- based frights/deaths would affect)

Bhagavatham

Even it is the same in bhagavatham i.e. when prahalada was given poisonous food by hiranyakasapa. food turned into divine as soon as kesava nama was taken.

Whether it is done knowingly or unknowingly (without understanding its meaning and significance) reciting the divine name will never go a waste. The best example of this is the story of Ajaamila as given in Ajaamilopakhyanam in Sri Mad Bhagavatham where Ajaamila chants unknowingly the name of Lord Narayana at the time of his death and gets rid of his sins. The one that is done by knowing its meaning and significance will not only eliminate the sins but also helps in gaining divine knowledge that leads to ultimate salvation

Various Practices

Aachamanam could be of different types arising from different scriptures viz. Vaidika, Srauta, Smartha, Pouranic and Tantric based on the ceremony/ritual being performed and on the line of learning that is being followed. There can also be difference in the rules followed. The difference mainly lies mainly in the mantras recited. Reciting of manthras during Aachamana differs from place to place, region to region based on sampradaya. Generally family tradition is followed. Whatever may be the type of Aachamanam followed, it’s very objective is one and the same that is, purification of the body and mind. It is said that Aachamanam should be performed twice at the beginning of Sandhyavandana Kriya and once/twice at the end.

In practice we find there are two types of Aachamanam which are in vogue. They are, Srouthaachamanam and Pouranikaachamanam also called Smarthaachamanam. The one that is performed with Gayathri is called Srouthaachamanam and the one which is performed with Kesavadi Namas is called Pouranikaachamanam. Majority follow the system of Pouranikaachamanam. It is said that while performing Sandhyavandana Kriya one should follow the Pouranikaachamanam and while performing Brahma Yajna Srouthachaamanam should be followed

Narada Purana

3 sips with the Gayatri Mantra

Devi Bhagwatam

3 sips with the Mantras

Om Keshavaya Swaha,Narayana Swaha,Govindaya Swaha

Linga Purana

3 sips with another Vishnu Mantra

"Om apavitrah pavitro va...."

With pre-collected water in a shankha or conchshell or atleast in a bowl of Kushaa, then perform three ‘Aachamanas’ or sips of spoonful of water while reciting the Mantra:

Apavitrah pavitrovaa sarvaavasthaangatopiva,

Yassmaret Pundareekaahsham sa bahyaantaraassuchih/

This would be followed by the Aghamarshana Mantras viz....

 Paipladins(a Shaka of Atharvaveda)

Om Pranaya Swaha,Apanaya Swaha,Vyanaya Swaha,

Saunaka Shaka(of Atharva Veda)

Om Jiva stha jivyasaM sarvamayurjivyasaM

Om Upajiva sthaop jivyasaM sarvamayurjivyasaM

Om Sanjiva stha Sam jivyasaM sarvamayurjivyasaM

Sri Vidya Tatva achamana 

Om Atma tatvam shodyami swaha,Vidya tatvam shodayami swaha,Siva tatvam shodayami swaha& Sarva tatvam shodayami swaha

Chinnamasta (or Nila Sarswati Sandhya Prayoga etc) 

Om atma tatvaya swaha,Vidya tatvaya Swaha,Siva tatvaya swaha.

Arya Samaj

Sip water from the right palm 3 times after each mantra; Om amrito pas-taranam-asi swaahaa. Om amrita-pidhaanam-asi swaahaa. Om Satyam yashah shreer mayi shreeh shra-ya-taam swaahaa.

Other related practices

For a guest typically when they arrive after washing feet and hands,achamanam is offered i.e. it following padya, Arghya and Achamana i.e. padya for washing feet, ardhya for washing hands and Acahamana for purification and also thirst. 

Reference

https://www.quora.com/Why-is-Achamanam-performed-at-the-beginning-of-every-puja

http://neetasinghal.com/significance-of-achamanam/

https://www.youtube.com/watch?v=H8JExXa2VTQ

https://www.youtube.com/watch?v=k9qbJISTLBo

https://hinduism.stackexchange.com/questions/3130/what-scripture-does-the-original-achamanam-mantra-come-from

https://www.facebook.com/notes/brahmasri-chaganti-koteswara-rao-garu/significance-of-aachamana-with-24-kesava-namas/387997491249655/

https://animeshnagarblog.wordpress.com/2014/07/27/achmanam-vidhi-for-atharvans/

https://greenmesg.org/stotras/vedas/apah_suktam.php

https://greenmesg.org/stotras/gayatri/gayatri_mantra_for_pranayama.php

https://vicharavedike.wordpress.com/2011/09/16/chaturvimshadhi-roopa-%E2%80%93-24-keshavaadi-roopas-of-lord-sriman-narayana-part1/

https://www.kamakoti.org/kamakoti/vishnupurana/bookview.php?chapnum=17

https://vicharavedike.wordpress.com/2011/09/16/chaturvimshadhi-roopa-%e2%80%93-24-keshavaadi-roopas-of-lord-sriman-narayana-part1/

https://vicharavedike.wordpress.com/2012/03/03/chaturvimshadhi-roopa-24-keshavaadi-roopas-of-lord-sriman-narayana-part-2/

https://vicharavedike.wordpress.com/2012/11/27/chaturvimshadhi-roopa-24-keshavaadi-roopas-of-lord-sriman-narayana-part-3/

https://vicharavedike.files.wordpress.com/2012/03/keshavanama_with_meaning.pdf