Water In The Diesel Tank.

Like all boaters using a diesel engine, I have heard many of the water in the tank horror stories. This problem is two fold. The first problem is - is there any water in the tank - the second is - is there diesel bug in the tank.

So the first item is - is there any water in the tank, the second conundrum is - how much. Thanks to Pete on Nb Joanie M answering the first question is easy. Pete gave me a tube of a product called Kolor Kut to try. A light smear of the gold coloured paste is applied to your dipstick and then the tank is dipped.

Where Kolor Kut comes into contact with water, the gold turns to red. In our case the light smear proved that there was some water in the tank. Between a quarter and a half an inch deep. Now the first question has been answered. I can address the second. With regard to diesel bug, I have been treating the tank from time to time with Marine 16. I recently changed the diesel filter and there was no evidence of the filter being blocked or contaminated in any way by the bug. 

On Rosie there is also in the fuel line a Wasp Filter (water and contamination trap) which I bleed from time to time. There has never been any evidence of water or other contamination in there.  I also have a normal diesel filter fitted. The filters will separate out any water from the fuel because fuel is being run through both filters many times. Excess fuel is bypassed back into the fuel tank and circulated again.

So now I have to look at what can be done to remove or reduce the water in the tank. Water often gets in the diesel tank from humidity in the air. A fuel tank that is left only partially filled. Is thereby allowing room for moisture in the warm air to condense inside the tank. So it is likely there is build-up over time with everyone's tank. So the first item is reducing contamination from water. So keeping the tank full to the top over periods  where the boat is not used is a good idea. As is treating the tank for fuel bug as a preventative rather than as a cure. 


It is generally accepted that there will always be a little water in the tank from bio-fuels that are now added to diesel. Biofuel holds a small amount of water that can over time separate out. The switch to the new low sulphur diesel means adequate filtration is now a priority.

One idea is the AquaSock, which uses a chemical that turns water into a gelatinous mass. The chemical is sewn into a porous sleeve of the AquaSocks material.

The AQ12 - Can pull out up to 12 oz, half pint or 340 ml. of water from your fuel tanks and will fit in an access hole of no smaller than 1 3/8" in diameter.

The AQ-28 - More industrial strength, can pull out up to 28 oz,  pint or 795ml  of water from your fuel tanks and will fit in an access hole of no smaller than 2 1/2" in diameter.

A similar product is the Water Eliminator a solution for removing water from fuel storage tanks, thereby reducing the potential for microbial contamination in tanks. The Water Eliminator helps to prevent service problems related to water contamination.

However, trying to pump out the bulk of the water at the bottom of the tank with a small hand bilge pump would probably be a very good starting point. So I have purchased one of these Hand Bilge Pumps.  The easier to remove water content should be cleared first. Then we can try some of the more unorthodox techniques to clear out the remnants. 




Otherwise, I will just have to live with my obsessive-compulsive urge and not act on it. That's never going to happen.


I will report back on how I go on.

Later....