Water in Diesel Fuel: What You Need to Know
Water and diesel fuel? Not the best combo. Even a tiny bit of water can cause some serious headaches over time, leading to rust, clogged injectors, and even leaks. But don’t panic—most of the time, the water content is pretty minimal, and it takes a while for any damage to kick in.
How Does Water Get Into Diesel?
Diesel is basically a mix of hydrocarbon chains and some additives, all refined from crude oil. The refining process isn’t perfect, so a little water always sneaks in. Standard low-sulfur diesel can have up to 0.1% water, while biodiesel can hold up to 1%. Not much, right? This water-in-fuel is usually no big deal—your engine is built to handle it. It vaporizes and burns off with the diesel.
But free water, the liquid kind? That’s where things get tricky. It can lead to rust in the fuel lines and filters, which is a problem.
Do I Have Water In My Diesel Car?
Water tends to sink to the bottom of the fuel tank, but this usually isn’t a concern for regular passenger vehicles—especially if filling up at a reputable gas station. Diesel quality regulations are pretty strict. For instance, EU standards allow only 200mg/kg of water in diesel (that’s 0.02%). Research shows typical water content can range from 0.003% to 0.1%. That’s all water-in-fuel.
The easiest way to check for free water is by inspecting the fuel filter. If the vehicle hasn’t been driven for a day or so, the water will settle at the bottom, making it visible when the filter is removed. Just be careful not to spill any fuel.
Heavy-duty vehicles, like those used in construction or farming, are more at risk. They often fill up from above-ground tanks that can accumulate water over time, which can then get pumped into their fuel tanks.
How To Get Rid Of Water In Diesel
Excess water in a passenger vehicle is pretty rare unless unregulated biofuel is used. Often, the first sign of trouble is when a mechanic finds water in the fuel filter. Misfires can happen if injectors get damaged, but that’s usually a sign of a bigger issue.
If water is found in the tank, it’s best to drop the tank and clean it out. If there’s significant damage, replacing the tank might be necessary. Using antibacterial agents can help remove any rust or gunk-causing microbes.
Finding free water in a new diesel vehicle is a red flag. It’s likely coming from a poorly maintained filling tank. Most water will mix into an emulsion, passing through the engine without causing harm.
Additives To Remove Water From Diesel Tank
There are additives out there designed to tackle water in diesel. Popular ones include brands like CRC Diesel Dry and ISO-Heet Water Remover. These don’t exactly remove water; they contain isopropanol, which bonds with water molecules, allowing them to pass through the engine as part of a combustible liquid.
After adding the isopropanol, give it some time to work—usually a few hours. It’ll sink to the bottom of the tank and bond with any water. Just make sure to follow the right ratios.
Can You Add Rubbing Alcohol To Diesel To Get Rid Of Water?
When considering rubbing alcohol, it’s essential to choose the right type. Most off-the-shelf rubbing alcohol is diluted with water, which defeats the purpose. Adding that to diesel just adds more water—definitely not the goal.
