The water can then be drained off by opening a valve in the bottom of the bowl and letting it run out,until the bowl contains only diesel. Many fuel filters contain a water sensor to signal to the engine control unit or directly to the driver (lamp on dashboard) if the water reach the warning level. Fuel filter - Wikipedia Is this answer helpful?Thanks!Give more feedbackThanks!How can it be improved?How can the answer be improved?Tell us howPeople also askWhat is a diesel fuel water separator?What is a diesel fuel water separator?About Diesel Water Separator. A diesel water separator is what you need to reclaim valuable fueland to purge impurities so that you can keep your business running on schedule and your machinery in tip-top condition. A diesel fuel water separator is a modular unit which uses removable filters and pressure differentials to separate water..Diesel Water Separator: Parts & Accessories | eBaySee all results for this questionWhat does a diesel fuel filter do?What does a diesel fuel filter do?Diesel fuel filters usually are made in the shape of a basin or bowl. This means the filter curves down. Water collects in the bottom of the bowl,while an open/close valve at the bottom of the bowl allows the water to drain from the basin,leaving only water. It's important to remember the chemistry of an engine.How Do Diesel Fuel Filters Work? | It Still RunsSee all results for this questionWhat does a gas filter do?What does a gas filter do?The fuel filter cleans the fuel of particles and debrisin the gas tank before it reaches the fuel pump. The gas tank can get rusted and retain moisture,causing the fuel to become contaminated. The fuel filter protects the engine from damage by making sure the fuel from the gas tank is clean.Fuel Filter Replacement Service & Cost - YourMechanicSee all results for this questionHow to replace my fuel filter?How to replace my fuel filter?Relieve the pressure in the fuel line before disconnecting it.Look at the old filter and the new one before disconnecting anything.Remove whatever is holding the old filter in place and remove it.Put the new filter on in the same position as the old filter.Replace whatever holds the filter in place,and make sure it’s secure.How to Change Your Vehicle's Fuel Filter - dummiesSee all results for this question What Does the Fuel Filter Warning Light Mean To prevent this, diesel fuel filters are designed to separate the fuel and water before it heads to the engine. The water is collected and must be emptied out occasionally, otherwise it will start to pull through the filter and make its way to the engine.Author: Spencer Cates How to Drain Water from Fuel Filter Diesel Separator Draining Water from Diesel Fuel Filter. WATER IN FUEL FILTER: Draining off contaminants and water should get done on a regular basis. It is so simple that you don't need to be a mechanic to achieve this important task - which takes only a few minutes. There is an important reason to drain water and dirt from a diesel engine water separator.