how much water should i add to neutralize 1000 milliliters oh ph 13

pH = 13 means pOH of 1 (pH + pOH = pKw = 14).

pOH = -log(OH^-) = 1
Therefore (OH) = 0.1
You can add H^+ to neutralize the OH^- and that will take 0.1 mole for a liter of solution.
If you want to dilute with water, the dilution is 0.1 x (1000/xmL) = 1E-7
Solve for x. It's a huge number, something like 1 billion.