What are the advantage and impact by using lower water content?

Water is treated as villain in Construction. nevertheless lower W/c ratio can lead to good but stiff concrete which is not reasonable in some RCC sections due to dense steel. There are some chemicals available which can act as water reducer and give you required workability also , but again it comes at a cost higher. Main advantages of lower water content is good strength & more homogeneous mix.

It is quite good to keep water to cement ratio of the concrete as low as can easily be placed,compact and finished.Because low water cement ratio gives higher strength,durability and least permeability.The mechanism involves is pretty complex.But in simple, more water added to the mix, then water molecule at microscopic level will be get availed by the hydration reaction leaving behind pores that causes the higher water absorption of concrete when get matured. That's why its advised to keep it low.Otherwise the problems to the concrete can occur when exposed to different harsh environments like acidic and sulfate mediums(liquid effluents of factories) or even in ordinary circumstances its functionality may be get affected. 

Advantage : A lower ratio leads to higher strength and durability

Impact : Make the mix difficult to work with and form

when we use low water ratio in the concrete mix, the strength of concrete leads to higher, but workability is harder. for that we must use enough number of vibrators 

As a matter of fact, there are many advantages to use low water in concrete including:

1- low water absorption

2- better cohesiveness between concrete layers

3- more connectivity between bars and concrete

4- more strength against notorious environmental behaviour

5-lowering the amount of creep and shrinkage

6-lowering the possibility of separation between aggregates.

the only disadvantage of less water is reducing the amount of workability in concrete which makes it difficult to pouring,curing...

In the globalized market water will be most precious thing in the market, each and every individual has to take step to save water for our future generation otherwise it will lead to third world war.