Boatloads of shame

The water deck fill is labeled “Water” for a reason. Photo by ChristopherBirch

Winter 2023

By Christopher Birch
For Points East

The three rules of life taught to every child:

  1. Never lick a sharp knife.
  2. Never cross a road without first looking both ways.
  3. Never mix up your deck fills.

So, how, after such enlightened indoctrination, could any sentient adult ever pour water into their boat’s fuel tank? Or fuel into their boat’s water tank? The deck fills are clearly labeled. Mixing them up is the most reckless and sinful mistake a person can make. And the results are dire.

Yet it happens all the time. I’ve known friends, customers, fuel dock attendants and employees who have all stumbled into this nautical nightmare. I view their mistake as akin to criminal negligence. I sneer with contempt at each and every one of these hapless fools.

Then, last October, I accidentally pumped diesel into my boat’s water tank.

“Shame. Boatloads of shame.” So goes the Avett Brothers’ song, and I can relate.

We’ve owned Sundance for nine years and have fueled her up countless times. Her diesel fill sits amidships on the starboard side, and prop walk sucks her stern to starboard when backing down, so we routinely pull up to the fuel dock starboard side to. But on this fateful October day, current and wind were such that it made sense to take a different approach to the fuel dock and land port side to. Sundance has an amidships water fill on her port side directly opposite the starboard side diesel fill. Both fills open with the same tool. I was distracted chatting with the fuel dock attendant while simultaneously tending to Bill, the dog, who was active. The water deck fill cap came off. The diesel nozzle went in. And I pumped diesel into my water tank.


* * *

Sweet holy mother-fracking ever-loving hell! The moment I realized my error, I exploded in a rage of self-hatred.

* * *

Okay, so the deed is done. Once you get past the chagrin and self-flagellation, how do you undo such a monumental mistake?

Step 1: Don’t compound the error by circulating the contaminated water throughout the entire water system. Cleaning the tank is a big enough chore. Cleaning or replacing the water heater and all the hoses, pumps, valves, and faucets in the water system would represent a significant escalation of the project. Avoid this by valving over to another clean water tank. Or, if no second water tank exists, tape off the water pressure pump switch, and also tape off any freshwater foot pumps to ensure that no one in the crew accidentally runs water from the contaminated tank into the water system. (On Sundance, we’re lucky to have a second water tank, so we made the easy valve move over to the clean tank. We live aboard the boat, and it was a big relief to have clean water still available to us while we tackled the time-consuming project of cleaning the contaminated tank.)

Step 2: Remove the fuel from the water tank. Fuel floats on top of water, so once we had the inspection ports open, the pink diesel fuel was right there in plain sight. Horrific.

I pumped only .6 gal of diesel before coming to my senses, so I didn’t have all that much fuel to collect. Our contaminated water tank has a handy drain valve, and I used this to drain the water beneath the fuel into the bilge. A film of slippery and smelly diesel clung to the walls of the tank as it drained. Working through the inspection ports at the top of the tank, I used oil-absorbent pads to soak up the puddle of fuel at the bottom of the tank. I then used more of the same pads to wipe the walls of the tank until they were dry, and the white oil pads no longer picked up traces of pink diesel.

Step 3: Determine if the tank is worth saving. A plastic tank will absorb diesel like a permanent stain and may never get sufficiently clean again. Fortunately, our tank is made of stainless steel. I determined that we could (and ultimately did) get it clean. Access ports are a great help. Our tank has three of them, and we would not have succeeded without them.

Step 4: Wash tank with dish soap, drain, rinse, drain, repeat. It was important to load this soapy water in from the deck fill since it and the fill hose are also contaminated with diesel. I repeated this no less than 15 times, hoping to finally produce a tank that had no smell of diesel detectable from the inspection ports. I found that a little bit of warm water did a better job than lots of cold water. I also found it helpful to scrub the walls and the inside of the tank with the soapy water using a sponge. The uncommon drain valve on this tank has been incredibly helpful. All water tanks should have such a feature. Many gallons of soapy water drained into the bilge during this ordeal, and that cavity became pristinely clean during the process.

Unfortunately, this handy water tank drain is small in diameter and draining ended up being the most time-consuming part of the project. Plenty of opportunities to sit and think and hum. “Shame. Boatloads of shame.” I eventually got the tank to look and feel squeaky clean, but I never came close to getting rid of the smell. I would catch draining rinse water samples with a cup, and that water always had a strong taste and smell of diesel – more work needed.

Step 5: Decontaminate. Someone in New Zealand who has no doubt made this mistake him, or herself sells a product to address this exact problem. It’s enzyme-based (whatever that means), and it may or may not be effective. I don’t know because I couldn’t locate any for sale in the U.S. The closest place the stuff was available was England. Shipping from there sounded both expensive and time-consuming.

Further online research came up with an alternate approach using the everyday household products white vinegar and baking soda, so this was the path I followed. The idea is to first wash the tank walls with vinegar to get rid of the diesel smell. Then wash the tank walls with baking soda to get rid of the vinegar smell. A lot of rinsing was, of course, involved too.

I worked these simple and inexpensive products through the tank in the correct order, then tried a sample from the final rinse. My ever-patient wife, Alex, and I agreed that the water now had a complex bouquet with notes of vinegar, baking soda, dish soap, and diesel. More work needed.

I had a hunch that the vinegar was the power hitter in my line-up of cleaning products, so I returned to that. (No disqualifications for batting out of order in this game.) I loaded a gallon of the pungent stuff into the tank and sloshed it around with my trusty tank sponge. I then sealed the inspection ports and let the tank sit for 24 hours. After draining and much rinsing, I repeated the process with a box of baking soda diluted in a gallon of water for another overnight soak. More rinsing followed. This time, a sample of the final rinse water had no smell and tasted clean.

Step 6: Blind taste test. Lingering concerns about the psychology of taste still had me worried. Even if the water from this tank was exceptionally clean, would we continue to imagine it tasted like diesel? To help quash this syndrome, I set up a blind taste test with water samples from both water tanks. The contaminated tank passed the test on the first try. We could not differentiate the bad tank from the good tank. And with that, the bad tank was no longer bad and has been back in service ever since.

In next month’s issue, I’ll review the process for reviving a fuel tank after an accidental fill with water – a careless mistake that’s equally problematic but requires a totally different remedy. I’ve cleaned up after this error on other people’s boats, but I haven’t committed this particular crime on Sundance – yet.

Christopher Birch is the founder of Birch Marine Inc. on Long Wharf in Boston. He is now out cruising full-time with his wife, Alex, aboard their 36-foot Morris Justine. Follow their voyage at