How do I calculate the total volume when i mix 1000 kg of glucose with 5000 L of water
You could calculate it only if 


you know the density of the substance being dissolved and of the solvent
there is no interaction between the 2 compounds, causing the deviation from the Raoult law and the shift of the final density.


If both assumptions are met, the final volume is 
$$V_{\rm mix}=\frac{m_{\rm 1}}{\rho_{\rm 1}}+\frac{m_{\rm 1}}{\rho_{\rm 1}}$$

where m and $\rho$ are respective masses and densities.

On the other hand, if the mentioned deviation is in place, the calculation will be wrong.

E.g. if you mix $\pu{1 L}$ of ethanol with $\pu{1 L}$ of water, then after cooling down ( as the mixture would heat itself), the result will not be $\pu{2 L}$, but $\pu{1.9 L}$

In such cases, it can be determined experimentally, or from tabulated data of solution densities. 

Or, the calculation above can be usually used as a good estimation, especially if there are no significant temperature changes during dissolution.