Why it is important to squat while performing achamana?

Question

An Achamana is a purificatory ritual that consists of sipping small amount of water from right palm after sanctifying it(the water) with mantras.

An Achamana precedes all Vedic ritual.

There are certain rules which are needed to be followed while doing it.A recommended posture for doing it is the squatting position(although i don't think that this is mandatory).

From this page:

1. Achamanam Sipping water sanctified by mantras

Sit in a squatting position, facing east or north. The hands should be between the knees. Bend all the fingers other than the thumb and the small finger slightly so that a hollow is produced in the palm. Take a very small quantity of water in the palm and sip, uttering the following three mantras (one sip for each mantra):-

   Achyutaya namah
   Anantaya namah
   Govindaya namah

Question-Why it is important to squat while performing an achamana?What are the advantages of squatting(in this regard) over any other postures like say Sukhasana or Padmasana?

A video demonstrating Achamana being performed in a squatting posture.

Answer 1

As per the Samvarta Smriti, Achamana , if done while sitting on a seat or while sitting on one's thighs,the act does not purify the performer.

That is possibly the reason why squatting is considered as the recommended posture for performing Achamana.

A S'udra becomes purified [by touching the twelve limbs] with his hand ; a Vais'ya, with water 'touching merely] the teeth. And a Kshatriya, by performing the A'chamanam with water reaching the throat, attains to purification. (21)

[By performing it,] being seated on a seat, or when sitting on his hams with a cloth girt round the legs and knees, or with one foot placed above another, one never attains to purification. (22)

Samvarta Smriti Chapter 1 Verse 22.

Given below is an image of Sri Maha Periyava in a squatting posture.Probably he is about to perform achamana or just finished doing so.