Water in Your Oil Tank – What to do about it?

If water has got in your oil tank, your fuel system and operation could be in big trouble as it can wreak havoc with your machinery, equipment and vehicles.

With the unpredictable British weather and its ability to change very quickly, if there is water in your oil tank, it will freeze and block supply pipework, causing damage and eventually a halt in operations.

This blog looks at exactly how water gets in your oil tank (mainly through rainwater and condensation), with advice on how to detect it and how to remove it.

How does water get into oil tanks?

We tend to think of oil tanks as sealed units, but the reality is that water is a natural element of the atmosphere, and unfortunately, oil tanks are not fully resilient to water.

There are two main sources of water contamination: condensation and rainwater.

Condensation calamity

Condensation is more common during the spring and summer months and in partially filled tanks. It occurs when cold water vapour meets a warmer surface. So as the weather starts to warm up, your tank’s internal temperature is cooler than the outside temperature.

Moist air cools down inside of the tank and causes water vapour in the air to form water droplets. These droplets form on the inner walls and, as water is heavier and denser than most fuels, a layer of water eventually settles on the bottom of the tank.

Allowing your tank to run low on fuel leaves more space for air which means there’s a higher chance of humidity and condensation.

A few water droplets are harmless, but as water accumulates over time, they can:

  • Cause corrosion in an oil tank
  • End up in the engine which can result in corrosion
  • Freeze in the fuel line end, preventing oil from reaching the engine

Risky rainwater

Ageing structure and a lack of maintenance can result in a number of factors that allow rainwater ingress to enter a tank, including:

  • Damaged vents
  • Faulty/corroded seals
  • Cracks or holes in the tank
  • Ill-fitting filler caps

People often suspect that water gets into a tank during an oil delivery. However, when your fuel is topped up, this disturbs any water or sludge on the bottom of your tank and causes it to become unsettled. This can disrupt the flow of oil through your pipework and lead to a blockage.

So long as you purchase fuels and oil from a reputable supplier such as Crown Oil, it’s highly unlikely that any fresh fuel you receive will be contaminated with water.

What happens if water isn’t removed from an oil tank?

It’s bad news for bacteria. While water wreaks havoc on your fuel system, it also creates the ideal breeding ground for bacterial microbes, which decrease your system’s efficiency.

Bacteria release acid that corrodes your tank, fuel lines, filter and burners, and sludge that settles on the bottom of your tank and fouls your oil.

If it rises to a level that reaches the fuel supply line, it could prevent a boiler or piece of equipment from operating at its best or even worse, lead to complete failure.

Corrosion commotion

If water is left in an oil tank for a long period of time, the inside of your tank will begin to corrode. So unless you get regular checks, you won’t be aware of the problem until operational problems begin to occur.

Corrosion is one of the most common culprits of injector problems. Sediment, water and bacteria will then form at the base of your oil tank and create a build-up of sludge.

This will eventually lead to leaks and other serious problems that will shut your system down, including damaged burner components, disturbed combustion and costly repairs, or even a full tank replacement.

To read more on the problems of tank corrosion, read this article – Avoid a Fuel Tank Corrosion Catastrophe with our 8 Easy Steps.

Rusty rascal

A rusty tank means a decrease in integrity. Water produces iron oxide (rust) when it comes into contact with iron and steel surfaces. These particulates cause abrasive wear to machinery and equipment parts.

Ice ice baby

Water freezes at just 0°C. If your fuel is contaminated with water, during the winter months, it can freeze and create ice crystals that act like any other hard particulate. These can create wear in fuel systems, cause blockages in fuel filters, and exacerbate existing corrosion damage by expanding inside larger cracks.

A filter’s role is to protect the engine by preventing hard particulates from passing through. But engines and filters cannot distinguish between sediment and ice, so problems caused by ice can be tricky to correctly identify as the ice will melt long before a lab inspection.

Angry abrasion

Water has a lower viscosity than diesel fuel, which therefore offers a lower lubricating cushion between the opposing surfaces of moving parts which causes abrasive wear.

How to check for water in your oil tank

At this time of year, we receive a lot of enquiries about problems with tanks; normally when a boiler, piece of equipment or machinery has started to play up.

It’s almost impossible to detect water contamination from an external inspection alone. So, it’s likely that you’re not aware of any water in your tank until external problems manifest.

Why is it difficult to detect water in an oil tank?

Water and oil don’t mix together; and water is heavier than oil, which causes it to sink to the bottom of your tank.

So, looking into the top of your oil tank won’t tell you much, which can lead you to think your oil is free from contamination.

How can contamination issues be prevented?

Conduct regular tank checks

Frequent planned tank inspections by a qualified and reliable company will give you peace of mind that your fuel’s in supreme condition and help you avoid huge expenses to repair or replace your damaged tank or oil.

Test your tank using water-finding paste

A water-finding paste during routine checks will alert you if water is present or give you confidence that your tank’s free from water. You can apply the paste using a dipstick or rod that’s long enough to reach the bottom of your tank.

How to prevent water from building up in your oil tank

The most palpable way to prevent water from entering your oil tank is to keep it in good condition. A proactive approach here is key; however, if you suspect or are told that there is water in your tank, it’s best to act quickly – a stitch in time really can save nine.

If left untreated, contaminated fuel can cause mayhem in machinery’s internal components, bringing operations to a halt and resulting in huge expenses.

  • Keep your tank topped up to avoid any empty space for air where condensation can form.
  • Have your tank inspected at least every six months by an OFTEC registered engineer. This will ensure your tank is in sound condition and able to withstand adverse weather conditions, as well as protect yourself from an expensive callout when something goes wrong.
  • Keep lids shut on your tank which may seem obvious, but it’s vital to make sure they are not loose to prevent rainwater from getting inside.
  • Shelter your oil tank to protect it from cold and windy weather conditions. This will stop ice forming on the exterior of the tank or snow sitting on or around it which can both reduce the temperature of the oil inside.
  • Tank dewatering at outlet pipes, through a bung, for example, will identify any liquid interfaces between the oil and water. A bung should be fitted 0.25 inches from the bottom of the tank, to provide an outlet for any water to escape whilst containing the oil. Your tank should be dewatered every six months to prevent water from collecting and causing severe corrosion.

If you believe you have issues with your stored fuels or oils in your storage tank, get in touch with our expert team at Crown Oil Environmental as soon as possible to avoid high expenses. We have a wide range of environmental services on hand to help you prevent water and microbial bacteria contamination and can help you tackle any problems if they have already transpired.

Ready to learn more and wish to discuss your options including industrial tank cleaning, fuel polishing and fuel uplifts for any fuels you no longer need. Simply call our fuel experts today on 0330 123 3399 to find out more and get started.

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