diesel in aft water tank

[John Langford]

After all these years making sure I had the right tank, I managed to put one gallon of diesel into the almost full (42 gallons) aft water tank on the first day of our summer cruise. That was two weeks ago. Beyond feeling incredibly stupid, I am looking for information on fixing the problem.

Here is what I have done so far. A nearby marine facility pumped everything out of the tank within 2 hours of the event. I then added about 15 gallons of water and a lot of Sunlight dishwashing detergent and went sailing.  I welcomed passing power boats as it helped slosh the brew around in the tank! After a week I pumped out that material (no sign of diesel) and repeated the soap and water treatment. The second treatment has been sloshing around for a week.

So, what do I do now? One suggestion was to pull the tank (I am assuming I can get it out through the aft cabin), put in an inspection port and get it steam cleaned. Another approach would be to clean it in place. I saw Jon Schneider's advice on the Board re using Oxyclean, but I couldn't find any other references to cleaning water tanks fouled with diesel.

Any advice about cleaning the tank would be welcome. We do use the tank for drinking water, coffee etc. so I have to get it really clean.

BTW, I don't need any help with the self-recrimination. I am very good at that on my own.

[Stu Jackson]

John, sorry to hear about your story, stuff happens, it's a boat.  My dock-mate on a 34 foot Sea Ray had the same problem, so he painted his deck fill caps, which had all been black, to red, blue and black, the obvious choices.  I borrowed his paint cans and re-upped the colors on our Catalina Direct covers, too.  No reason you can't do that to your newer ones, too.

Here's where to go to find the answer to your question:  http://c34.org/bbs/index.php/topic,4208.0.html

It's a long two page thread, please go through it all.  I have, over the years, been fond of the work of Peggie Hall.  Her material was on our website well before her book was published, and was removed, reasonably, when the book did come out.  She, however, is a wonderful person and regularly republishes on websites, especially www.catalinaowners.com, her "Water System Recommissioning Instructions."

Accordingly, I have used the search word "recommissioning" in originally posting and then easily finding those articles.  While a search here on this Message Board on that word brings up fuel tank results as well, most of the hits are on water systems, pretty obvious by the titles.  I also use it on co.com to find that article to repost if Peggie is "out of the office."

I believe you have a situation that is "cleansable" without removal of anything other than perhaps some old hoses, which probably isn't a bad idea to perform, anyway.

All the best, and it's nice to know it's NOT as bad as you might have thought.

[John Langford]

Thanks Stu. The thread you pointed me to was the one I found via the search engine which includes Jon's recommendation of Oxyclean. But that thread is focused on cleaning a tank that may be "dirty" as opposed to one that has been "polluted" by diesel. Perhaps my question will evoke a response from someone who has successfully cleaned a polluted linear polyethylene tank.

I am definitely going to do something to differentiate the two filler caps. But, as you know, guarding against the last accident is usually a mug's game.

[Braxton]

Here is an old trick form my chemistry class days.    Poor a fair bit of acetone in the tank and let it slosh around.   Drain the tank.   The acetone should have mixed with the remaining diesel and should flush it out as it drains.   Vent the tank as much as possible (you could hook a fan to blow in via the drain while venting out the fill).    The acetone is volatile enough that it should all evaporate with the venting process.

Ideally this leaves you with a tank cleaned of the diesel via the acetone and cleaned of the acetone via the venting.   Do this and "viola" you have a clean tank.

Now for the not so fine print.   I've used this method to clean many tanks many times, but never one that I would be drinking out of later.   You should definitely do some research about what ingesting trace amount of acetone and/or diesel may do to you.   Here's one link that I found:  http://www.des.state.nh.us/factsheets/ehp/ard-ehp-7.htm.   Definitely do some exhaustive research on what you'll be ingesting before you drink out of this tank again, whether or not you use my method.

[Stu Jackson]

John, perhaps I wasn't clear enough about reading the whole thread beyond Jon's Oxyclean.  Reply #21 on page 2 included this link to Peggie's suggestions for treatment:

http://archives.sailboatowners.com/pviewarch.htm?fno=20&sku=2008080092417.62&id=530067&ptl=#2008080203957.66

You have many options, your boat, your choice.  If it was my boat, given the great job you did getting the diesel out originally and quickly, I'd follow Peggie's advice, bring some bottled water for the first trip, keep tasting, etc.  I wouldn't rip my tank out.

Or you can go to co.com and ask her directly, just post a question in the Head Mistress Forum.  She's very good at helping.

[Ted Pounds]

you might want to consider plumbing a good water filter into the pressure side of your system.  I used an ice-maker filter from Lowes and it worked well.  It's a good thing to have because tanks can become contaminated even if you don't pump diesel into them. 

[Roc]

John,
Maybe you can cut an inspection port into the tank.  This way you can get your arm in and the ability to scrub the inside. 

[Rick Johnson]

How about a couple gallons of cheap booze? Let it slosh around for a few days and then drain the tank.  Maybe tequila?  Any remaining diesel would dissolve in the alcohol and be flushed away....  Besides it would smell good....

Cheers (hic...),

Rick

P.S. Just found some addition information....

http://www.sailmag.com/Letters/watertank/

[John Langford]

Thanks folks. I have removed the second load of soapy water and following the advice of the stern mistress I have followed up with a 5 hour chlorox treatment and vinegar. I have renewed the hose from the deck fill to the tank and I may do the vent hose as well. But the line from the tank to the manifold under the sink never experienced the diesel so I am going to keep it.

I drained these treatments into the bilge and was surprised to find that my Sure Bail bilge pump switch didn't work. I think the problem is that the bilge has been completely dry and the switch is never activated. I am going to replace it immediately.

I saw the Calder vodka thread as well but there is no such thing as cheap booze in Canada so vinegar will have to do:)

[John Langford]

Further note on progress in cleaning the tank. After the treatment outlined above and many full flushes I still was getting an unpleasant taste although there was no sign of any diesel in the water. The water testing folks said that I had done all the right things and advised against wasting money on a water quality test. They, like Ted, recommended a filter. So I installed a 6000 gallon Shurflo filter with 1/2" barbs in the line from the aft tank to the tank manifold under the sink. I  cut the line in the small locker directly aft of the cabinet in the aft cabin. The filter allows 2.8 gpm to pass through so you hardly notice any reduction in flow. More important, the bad taste has disappeared completely.

Thanks for the advice and support. Hopefully,I can now put this regrettable incident behind me.