Assuming this water in the beginning of the question is also vapor, Dalton's law of partial pressure tells us that the sum of all pressures in a sealed container is equal to the total pressure inside the container, therefore:
Ptotal = P(CO2) + P(H2O)
1.75 = 0.88 + P(H2O)
P(H2O) = 0.87 atm
1 atm is equal to 760 torr, therefore 0.87 atm = 661.2 torr