Question on diesel tanks

[Mmary]

Hello, I’m considering turning my aft water tank into an auxiliary diesel tank, with a 12 v pump that will refill the main tank when needed.
The technician tells me I can put diesel in the water tank to make the conversion. I’m looking for second opinions or to be warned of any potential hang ups. Is it safe to do this?

[Wolfe10]

What material is your tank made of?


What boat?

[Mmary]

Jeanneau 50
The water tank is of a thick blue plastic.

[Hobby]

There is a discussion on converting water and diesel tanks on the Jeanneau board.
https://jeanneau.proboards.com/threa...ing-water-tank
If you have not already joined, the Jeanneau board is an excellent resource for all things Jeanneau.

[NorthCoastJoe]

I did this with aluminum tanks gaining 96 gallons of fuel as a reserve. It was an easy job.

[Scorpius]

Perhaps this isn't a concern with plastic tanks, but but welded metal tanks that hold water just fine may leak when diesel is put into them. Diesel molecules seem to be able to slide through tiny channels through welds that water can't.