Diesel in the Water Tank: What Now?

August 13, 2021 in Tips for Owners, Maintenance & appliances & Tips for the road

It sounds terrible, but we promise it’s not as bad as it sounds, and it happens more often than you would think! Accidentally putting diesel into the water tank is a common mistake by new campervan travellers, and the most important thing is how you proceed after the mistake has been made. Damage can be avoided, which means so can repairing or replacing the water tank and pipes. But only if you act quickly and correctly! So what should you do if diesel is in your water tank? Follow these simple steps and you’ll have it sorted in no time. 

Goboony diesel campervan motorhome h2 water tank

The minute you realise that something is wrong, you should immediately switch off the water pump or, preferably, your entire electrical system. Even if you’re not sure that’s what happened, do this as a preventative action. This will ensure that the diesel doesn’t end up in the water pipes, which is far more challenging to handle. Empty the water tank quickly, to ensure the diesel doesn’t soak into the plastic lining of the water tank. 

Here is how you clean diesel out of the water tank:

  1. First, locate the valve, place a container under it and then drain the water tank completely.
  2. If the diesel has progressed to the pipes, still begin by emptying the tank completely. Confirm that the water pump is turned off, and then open the taps. The taps will now ‘suck’ in air, and the pipes will drain below.
  3. Unscrew the cap on top of the water tank and then dry the tank with any cloths that you can later wash at a high temperature or get rid of.
  4. For a 100-litre tank, buy 10 litres of Diesolan. For different sizes, use that 10:1 ratio to calculate the amount. This cleaning fluid is designed specifically for this purpose and can be purchased online on Amazon, particularly the brand Dr Keddo.
  5. Fill the tank would 3.3 litres of Diesolan and 20-30 litres of water. 
  6. Drive around for 10-15 minutes to allow the contents to mix well.
  7. Empty the tank after four hours (or a maximum of twenty-four hours). Diesolan is biodegradable. 
  8. Fill the tank with 20-30 litres of water. 
  9. Drive around for 5-10 minutes so that the contents can mix well before emptying the tank again.
  10. Follow the steps above once more, but this time leave the Diesolan in the water tank for an hour. 
  11. Follow the steps again for the third time, but this time leave the Diesolan in the water tank for only fifteen minutes. 

Help, I can’t buy any Diesolan

If Diesolan is unavailable or you don’t wish to spend that much on a manufactured solution, we have another solution that costs less than £5!

A lot of motorhome owners have had good experiences with the following approach:

  1. First, perform steps 1 to 3 above. 
  2. Buy two tubes of Steradent (denture cleaner).
  3. Fill a 100-litre water tank with 30 litres of lukewarm water.
  4. Put the Steradent in the water tank. 
  5. The water will now turn pink/blue and begin to bubble a lot. 
  6. If there is also diesel in the pipes, open the tap until coloured water begins to come out.
  7. Drive around for 10-15 minutes so that the contents of the tank can mix well. 
  8. The next morning, empty the water tank. Alternatively, wait 10-12 hours. 
  9. Fill the tank completely and then empty it again, and if necessary, flush out the water pipes. 
  10. Repeat step 9. 

Goboony diesel campervan motorhome h2 water tank

It is essential to realise that just flushing the tank won’t solve the issue. The diesel penetrates into the plastic, so the diesel scent lingers, and you won’t be able to remove it with ordinary cleaning agents. 

Not everyone knows that you can easily fix this issue with Diesolan or even Steradent. This in unfortunate, because if you don't take action as described it's likely the water tank and pipes will have to be replaced, which can be an expensive job. 

Do you have any other tips for getting diesel out of the water tank? Let us know! 

If you’re hiring out your motorhome, you can avoid issues like this one with an extensive handover video