Apparatus in fluid communication with a water leg portion of a hydrocarbon-contaminated water, e.g., a water leg portion of a produced water stream or an offshore drilling or production platform sump tank for conveying water, separated from oil, into contact with non-woven fiber/particulate polymer coalescing media-containing canisters such that the hydrocarbon droplets and other organic material droplets commingled with the sump tank or produced water will be coalesced by passage through the coalescing media. The canisters preferably are provided in a plurality of stacks in each vessel. Solids that do not pass through the canisters are accumulated at the bottom of the vessel and easily drained through a drain port. The water and hydrocarbons will pass through the coalescing media within the canisters and will be separated easily from each vessel, e.g., by gravity separation, sot that the water can be conveyed back to the ocean water without contamination.