Ask Honest John

Honest John Ask Honest John » There's potentially water in my car's fuel tank. What should I do?

There's potentially water in my car's fuel tank. What should I do?

I left the fuel cap off my petrol Kia. I didn't find this out for 3 weeks whilst on holiday. Rain probably got into the fuel tank. What should I do?

Asked on 29 July 2021 by Barry Boyers

Answered by Dan Powell
To be on the safe side, I would recommend having the fuel tank drained and the fuel lines flushed. The water level in the fuel may be minimal but there is no real way of visually checking this as diesel is lighter than water (which means the water will be at the bottom of the fuel tank). If there is water in the tank then it could damage the injectors. Water can also produce bacteria, which forms an unpleasant sludge in the tank that will clog up the fuel filter.

A fuel drain will probably set you back £300 - £400 (or £700 - £800 via your Kia dealer). But it'll be cheaper than risking water damage to the engine and fuel tank.
Similar questions
Any advice on pursuing a claim related to repairs associated with a contaminated diesel issue? The retailer is claiming that no other reported issues have been raised and that their own test records indicate...
I have a BMW 116 2006 model where everything seems to be fine until petrol is low the symptoms start to show. First the engine management light will come on and than there will be a loss of power on acceleration....
Last week I filled my Mercedes-Benz Vito van, but 24 hours later the entire injection system was destroyed, with repair cost amounting to £4500. The dealer who carried out the repair confirmed that the...