The fuel filter/water separator comes in three parts, the head, the disposable canister filter and a clear,water/sediment bowl.
If you unscrew the plastic top you will see in the centre of the filter head a plastic fitting with 2 small vanes on the top.
As the fuel flows into the filter it turns these vanes and separates water/sediment from the fuel.
As the bowl is clear you can see any water/sediment and you simply open the drain at the bottom to remove it.
The filter is a Cat Fuel/Water separator part no 159-6102.
A simple, cheap and effective system with a sump and drain on the main fuel tank, not once in over 40 years cruising have I ever broken down with contaminated fuel.