I can imagine that the diaphragm of the sensor will fail chemically fail at some point, it isn’t listed as being guaranteed to work in such conditions so I would proceed with caution and be ready for it to fail much faster than it usually would when used in water.
The 0.5% accurate spec is a bit vague so we’ll do some more digging to see what exactly that means but if I had to guess it would be the pressure reading was ±0.5% off the real value. Ultimately to get the best result you will also need a higher resolution ADC to get the most accurate result
It might also be worth checking out a non-contact type of sensor such as an ultrasonic sensor (the linked sensor might not be the best one for the application, for mounting in a tank you’ll have to take note of the geometry).
Let us know if you have any other questions!
Liam.