how much positive and negative charge is there in a cup of water

 they must be equal as charge can neither be created nor be destroyed.

 how much positive and negative charge is there in a cup of water

Assume that one cup holds 250 ml of water.

250 ml = 250 gram of water since its density is 1 in cgs.

number of moles of water in 250 gram = 250 / molar weight of water

n = 250/18 = 13.88 moles

1 mol has 6.022 x 10²³ number of water molecules

So 250 g water will have 13.88 x 6.022 x 10²³ number of H₂O molecules

= 8.36 x 10²⁴ number of molecules

One molecule of water has 2 hydrogen atoms (2 protons) and one oxygen atom (8 protons).

Total protons = 10 = total electrons (since it is neutral)

So 250 g water will have 10 x 8.36 x 10²⁴ = 8.36 x 10²⁵ protons.

charge of proton = 1.6 x 10^-19 C

So total positive charge of 250 g water = 1.6 x 10^-19 x 8.36 x 10²⁵ = 13.37 x 10⁶ C

which is equal to 13.3 MC (mega coulomb)

So one cup of water has 13.3 mega coulomb positive and negative charge, so that the overall charge is zero.