Water contamination of Polyol F0350
Tricky question, but it probably has a trivially simple answer if you have experience with this problem, such as the 'look' of the mixture in the tanker. Not quantitative of course but possibly accurate enough, thus it could be worth asking others with experience for their opinion.

Assuming that water is intimate with the organic, i.e. dissolved or as an emulsion, some water needs to be separated out then there is the Distillation method which uses an immiscible organic with a boiling point higher than water, say xylene. The water is quantitatively carried over with solvent and can then be analysed.

Conductivity would be one way but not conclusive, as both industrial water and sea water may conduct or industrial water may not conduct and so be similar to distilled water. However, the distilled water may also conduct as its not de-ionised water. A simple test unlikely to be definitive definitive, but if its sea water, then a simple flame test should show sodium, as may industrial water, but distilled water far less so. Industrial water may contain soluble organics as well as various inorganic ions so may be coloured, acidic or alkaline and have a distinct smell. The sea water and distilled water have known pH. 

Ultimately you will want to do a proper analysis, say GCMS.
Finally, after separation, water could still be present in small amounts in the organic then there is the Turbidity method or the Karl-Fisher titration to determine the amount of water left in the organic layer. However, I suspect you are asked to to a test at the back of the tanker or at least with very simple apparatus. 

Mitigation is decided by company policy and this probably depends on what the cost is to correct the problem. 

I hope that someone with real experience of this can help, that is when they have stopped laughing at my amateurish ideas.