The quantity of required water is following.
1.Water for nominal mix concrete shall generally be equal to 5% by weight of aggregate and 30% by weight of cement.
2.Generally for vibrated concrete the quantity of water will be less by 20% but the actual quantity shall be determined by the field test for slum.
3.For one bag mixture, 32 liters of water is required and the ratio will be 1:2:4
4.For one bag mixture, 30 liters of water is required and the ratio will be 1:1.5:3 , for more information about cement concrete please visit gharexpert construction section concrete sub section.