Diesel in the Fresh Water Tanks?

How does that even happen? The crew of Del Viento finds out.

January 16, 2015

I can’t think of any place more suited than a cruising sailboat to expose the differences between people, in terms of how they think.

Take Windy and I. I’m a quick and efficient problem assessor and solver (or I wisely realize when a problem doesn’t need solving) and can be driven to madness by Windy, whose approach can only be characterized as a painfully slow and irrational consideration of every conceivable angle before reaching a conclusion.

“There’s diesel in our fresh water.”


She said this about six weeks ago. I wrote about it here, what I knew then.

“How did it get in there?” she asked.

“I don’t know, must have come from a contaminated bottle that we dumped in.”


“It must have?”

“Sure, no other way it could have gotten in.”

Plain and simple, problem solved, not an open question that has to be analyzed for weeks, certainly not one that warrants repeated, frustratingly irrelevant questions to your husband about the boat’s fresh water system and how he plumbed it when he installed the new tanks back in La Cruz three years ago…okay, surely you see where I’m going with this.


“I figured it out.” She announced recently.

“Figured what out?”

“I know how the diesel got into our water tanks.”


“Not from contaminated water bottles in Bahia de Los Angeles?”


And she’s right, it’s not from contaminated water bottles.

Apparently, the fresh water tank vent hose that I’d left open to the bilge—the extra-long hose that I planned to someday plumb to the galley sink—had fallen into the bilge. (Of course, the bilge that is perpetually wet from the vent-line overflow that happens every time we fill the water tanks.)


So, our fresh water galley gusher foot pump (we have two of them, one for fresh, one for salt) failed this summer and after rebuilding it and when I began to reinstall it, I realized that the screw holes in the wood base inside the cabinet on which it’s mounted, were worn, stripped. The bigger screw I then used in one of the holes busted the plastic mounting base of the pump.

So we switched to pressure water until we could get it fixed. (We’d not used pressure water in a year.)


So when the pressure water pump drew from a tank with the vent line submerged in bilge water, it created enough of a vacuum to suck that bilge water into our water tanks. (The foot pumps never created such a strong vacuum.)

And there is diesel in your bilge?

No, but there was—traces that wept out of a fitting on top of that tank when we last super-filled it this summer. But now it’s in our fresh water tanks.

The good news is that after weeks of tank cleaning (vinegar, rubbing alcohol, dish soap), engine running (it’s in the hot water heater too), and incredibly profligate water use, I’m finally drinking from our tap (Windy and the girls aren’t there yet, but soon, very soon).

Click here to read more adventures from the crew of Del Viento!

Galley Sink with Water Tank Vent

Galley Sink with Water Tank Vent

So here is the fount of the problem, so to speak. Unlike a house, galley sinks often feature a bunch of spigots, some more than us. The main one that looks like the one in your house, handles all the fresh water, whether pressure or pumped, but not simultaneously. The smaller tap in front of it is for pumped salt water, that we can use to wash dishes. And the little guy flush to the sink behind it, that’s our new water tank vent. Michael Robertson

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