In order to fully understand the meaning of the term water balance, it is necessary to previously proceed to analyze the etymological origin of the two words that give it its shape:
-Balance is derived from French, exactly from the word “balance” which is synonymous with balance..
-Hydric, on the other hand, is a word that comes from the Greek. Specifically, it is the result of the sum of two clearly delimited components such as the noun “hydor”, which is synonymous with “water”, and the suffix “-ico”, which is used to indicate “relative to”.
The concept of balance can be used in reference to the swaying of an object that is alternately moving to either side. The notion also refers to the economic analysis of monetary income and expenses and the comparison that is made of a situation to draw a conclusion. Hydric, for its part, is that which is linked to water as an element that appears in nature.
These definitions allow us to approach the notion of water balance, although first it is necessary to clearly establish what the mass balance is. It is a method of mathematics based on the law of conservation of matter, which indicates that matter is neither destroyed nor created: it is simply transformed.
Respecting these principles, the matter balance considers that the mass found in a closed system remains constant (with the exception of atomic or nuclear reactions and of matter that reaches a speed close to the speed of light). Thus, when mass enters a system, it must either accumulate in it or leave it (input equals accumulation plus output).
If we return to the idea of water balance, we can affirm that it is the relationship between all the water resources that enter a system and all the resources that leave the same system in a certain period of time.
According to DigoPaul, a water system can be a lagoon, a river, a dam or even the body of a person, to name a few possibilities. If we take the case of a lake, the inflows of water resources can be produced by rain, the transfer of water from a water basin or the contribution of groundwater, while the outflows of resources can be due to evaporation, extraction by part of the human being, infiltrations, etc.
It must be established that within the health field the concept of water balance is also used. Exactly it is used to refer to the balance that exists between the water resources that reach the body and those that leave it in a given period of time. And this is how you can control that the body has the amount of fluid it needs to continue to function with absolute normality.
In this case, it is considered that the water that reaches the body does so both through the liquids that are ingested and also through the food that is eaten. In this way, it is established that the entry of liquid into the body is usually between 2,100 and 2,900 milliliters. Of that amount, it loses about 2,400 milliliters per day due to sweat, urine, feces…
The balance, therefore, can be altered by specific situations such as vomiting, diarrhea, bleeding, excessive sweating…