Yin & Yang exist mutually, without one the other ceases to exist.
Question. is Water Yin Or Yang.?
Answer.    It can be either, it depends how and what you reference it to   :-

e.g. consider the process of
[1] Ice melting to Water and then .......
[2]Water turning to steam.

In [1] Ice (cold, solid) is more Yin compared with Water (warmer, fluid) which is more Yang
In [2]Water (fluid) is more Yin  compared with Steam (light, vapour) which is more Yang

There are no limits to the scale Of Yin & Yang
i.e. In Gross terms
Infinity - universe( more Yang  ) to almost zero -one solitary electron (more  Yin )
Or in more minimal terms :-
a rise in temperature from 20 Degrees (more  Yin ) to 20.00000001 Degrees (more Yang )

In general usable terms:-

Yin relates more to Coolness (  the most Yin  state of water is ice), ovum, earth, rest, darkness (Black), inward, concentrated, Acidic.
Yin meridians are on the front of the body & inner surfaces of the limbs.
They are relatively solid organs (kidneys, liver, heart, heart, heart governor, spleen, lungs).
Yin organs are deeper, internal and deal with the transformation, circulation, and storage of Qi and blood.
Yin emotional trends are spiritual, open, peaceful, joyful, creative, colourful, tolerant, non-conformist (hippy like).
Yin arrogance - the feeling that no one can help them.

Yang relates more to Warmth ( most Yang  state of water is steam), sperm, heaven, activity, brightness (white), outward ,expanding, Alkaline.
Yang meridians are on the Back of the body & outer surfaces of the limbs. They are relatively hollow organs (bladder, gall bladder, small intestines, triple heater, stomach, large intestines).
Yang organs are more surface including the digestive tract that deals with receiving / processing food and eliminating waste.
Yang human tendencies are decisive, purposeful, concentrated, clean, orderly and polite.
Yang arrogance - if you try to give them help they know better.

Yin describes the Shady side of a slope.

Yang describes the Sunny side of a slope.