Oil spills are often associated with large-scale catastrophes like the 2010 Deepwater Horizon spill that stretched the Gulf of Mexico. Images of a thick black layer coating the ocean with oil-soaked birds and sea lions stranded on the shore fill our minds and the impact of these disasters feel somewhat detached from our world.

But an oil spill doesn’t have to consist of thousands of gallons spilling into the oceans to have serious and devastating consequences. And they’re probably far more common than you’d think. It’s these little, but consistent oil spills—that occur on land and rivers as well as oceans—that can often prove the biggest threat to our environment, wildlife, and health.

When these small oil leaks happen—especially on asphalt and concrete— they are often hard to detect. Usually, the first telltale sign of an oil leak is the “rainbow” effect on the affected surface following rainfall.

rainbow like reflection from oil spilt on tarmac

Causes of oil spills

It is said that 80% of all hydrocarbon (oil is a hydrocarbon fuel) spills happen on land due to failure of vehicles, heavy duty equipment, and recreational boats.

Spills of this type collect on concrete, asphalt, and other hard non-porous surfaces. And when it next rains, this collection of oil can soon find its way into waterways, the drainage system, and surrounding soil. Not only can this have a devastating impact on the local wildlife and ecosystems, it could also affect human health with the potential to contaminate our drinking water.

Oil spills on both land and water can be caused by a variety of different causes including a lack of maintenance of vehicles and/or equipment, the malfunction of vehicles/equipment, accidental or malicious damage to vehicles/equipment, and even the illegal dumping of oil.

There are common culprits for causing oil spills and leaks. And places such as substations, power plants, refineries, and mariners are particular hotspots. With a constant need for maintenance, the ability to control and contain oil before it becomes a problem is paramount.


Diesel spills are the most common on highways—whether that be consistent leaks from faulty vehicles or large spills following an accident. As with other types of oil spill, they shouldn’t be taken lightly. In March 2018, a lady from Chislehurst in Kent was fined £1,000 after oil was found to be leaking from her car. Transformers, degraded engine gaskets, oil pans, overfill, and oxidised fittings, holes in hoses, or seal incompatibility are just some of the common faults that can cause oil spills or leaks.

Domestic Oil Tanks

It’s easy to assume that most oil spills are the responsibility of commercial or industrial incidents. However, in recent years, there has been an increase in the number of pollution incidents caused by faulty or badly maintained domestic central heating oil tanks.

Some of these incidents have caused drinking water to become contaminated, putting health at risk. Other spills have led to houses being evacuated due to the odour and fumes which have made it impossible to live in the neighbouring properties.

In either case, the work to investigate, rectify, and restore the areas following an oil leak or spill can very quickly begin to run into the tens of thousands of pounds.

It’s easy to assume that your insurance company would cover the cost of an oil spill or leak on a domestic central heating oil tank, but this isn’t always the case. If you’re unsure as to what you are and are not covered for, speak to your insurers.

Nature and Oil Seeps

But let’s not forget nature’s role. Natural disasters such as hurricane Katrina caused a significant amount of oil to affect the Atlantic Coast. It is estimated that eight million gallons of oil spilled onto the ground and into the waterways, making this the worst oil spill in American history. This was later surpassed in 2010 by the BP disaster which affected much of the same areas along the Gulf Coast.

It is said that as much as one half of the oil that enters the coastal environment comes from natural seeps of oil and natural gas. The lighter compounds rise to the water’s surface and evaporate or get caught up in the ocean currents. Heavier compounds fall to the seafloor where they collect over hundreds or thousands of years.

So with this in mind, you may be wondering why there’s such a big concern about the occasional oil spill such as those mentioned above. It’s mostly due to the nature and rates of oil input.

Natural oil seeps are generally very old and flow at a very low rate. While they’re mostly still toxic, it’s likely that the nearby organisms are climatised and adapted to the conditions in which they live. There’s even a few unique species of animals who are able to use the hydrocarbons and other chemicals released at seeps as a source of metabolic energy. Additionally, the oil generated from seeps is often heavily biodegraded by microbial action, deep beneath the seafloor.

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Damage caused by oil

Oil spills on land can be just as devastating as those in the ocean, although they are often somewhat simpler to clean up and restore. However, oil spills which are ignored can go on to cause a lot of damage to the surface it’s spilled on, the neighbouring ecosystems, environment and wildlife, and your reputation as a business.

An oil spill on concrete—if left—will begin to break and weaken the concrete itself. Oil spills spread faster in wet weather and if not contained and controlled quickly, can rapidly start costing into the thousands to remediate.

The damage caused by an oil spill will differ depending on various factors, including the chemical composition of the oil, the affected area, the time it remains in the environment, and the cleaning method applied.

Oil spills don’t just pose a slip and fire hazard, they can have much further reaching consequences…

Damage to the environment and wildlife

Oil spills can be extremely harmful to the environment, neighbouring ecosystems, and the local wildlife. Oil can contaminate water and release harmful contaminants, significantly affecting surrounding vegetations and habitats. These adverse effects on the environment can be both short and long term.

The chemical constituents within oil are poisonous. They can affect organisms from internal exposure to the oil (via ingestion or inhalation), and from external exposure (such as through skin contact).

Oil can be deadly to wildlife. If an animal comes into contact with oil, they can suffer immensely. Oil can penetrate into the structure of the plumage of birds, and the fur of mammals. If this happens, it can significantly reduce their ability to insulate (keep themselves warm), making them vulnerable to temperature fluctuations, as well as making them far less buoyant in the water.

For those animals who rely on scent to find their mothers or babies, being coated in oil is virtually a guaranteed death sentence. With the smell of oil overpowering an animal’s natural scent, a mother will be unable to find her babies, and vice versa. Ultimately, this will lead to the babies being abandoned and eventually starving to death.

Animals can be blinded by oil, leaving prey even more vulnerable and defenceless, and predators unable to hunt. Digestive systems are impaired by the ingestion of oil and it can also cause dehydration. The animals themselves may suffer from the poisonous properties of the oil, or their organs can fail—for example, if oil enters into their lungs or liver.

Damage to your business

Your business can not only suffer financially, but your reputation can suffer significantly. As the size of the spill increases, so does the labour cost, material cost, disposal cost, clean up cost, potential environmental fines and potential legal fines. And if the spill enters into the soil or waterway, there will be even more added cost.

Indirect costs can include damage to your reputation. From bad publicity and consumer bias, to a decrease in positive feedback and association by big clients and customers. If the spill is big enough, or mishandled, you could find your company as the target of added public scrutiny. This damage to your reputation can have a significant impact on your bottom line.

The worst kind of oil

Not all oil spills are equal in their potential for damage. It will largely depend on the type of oil spilt (heavy or light), the type of environment it enters, how long it remains in said environment, and what methods are used to remediate it.

The type of oil spilt makes a big difference; they behave differently in the environment, and they also affect animals and the ecosystems differently. So let’s take a look at the differences between the two: light and heavy.

Light oil—such as fuel oil like gasoline and diesel—are very volatile, meaning that they evaporate quickly. As a result, they do not tend to stay in the environment for very long, particularly in marine or aquatic environments. If a light oil spreads out onto a body of water, it still usually evaporates relatively quickly.

It would be easy to assume that the risk of light oil spills is low. But unfortunately, that isn’t the case. Despite evaporating quickly, light oil poses significant risk while in the environment. For a start, it’s extremely flammable, causing another huge risk altogether. Moreover, light oil is incredibly toxic. It can not only kill animals and birds that come into contact with it, it’s also incredibly dangerous to humans who inhale the fumes or make skin contact with it.

Unlike light oils, heavy oils—such as bunker oils used to fuel ships—can stay in the environment for months, even years if not dealt with. Often black and sticky, they are actually commonly less toxic than light oils. Rather than posing a risk from their toxicity, their threat comes from the short term associated with the spill and their ability to smother plants, animals, and wildlife. This smothering can cause significant side effects like those listed previously, as well as causing tumours in some organisms.

If birds come into contact with heavy oil, it can get into their feathers and cause hypothermia which is often fatal. After a few days to a few weeks, heavy oil hardens and becomes similar to asphalt. In this hardened state, the heavy oil is less likely to cause harm to animals or plants it comes into contact with.

Dealing with an oil spill

If you experience an oil spill, it’s vital that action is taken as soon as possible to firstly contain it, and secondly, to clean it up. Failure to do so can result is a more expensive cleanup operation as the oil begins to seep into the surrounding environment, and if this happens, you could find yourself facing hefty fines.

Oil spills are classed as pollution, and all pollution incidents should be reported to the appropriate authority as soon as reasonably possible to mitigate damage. If life and/or property is threatened, then emergency services should also be called.

If an oil spill is likely to affect rivers, lakes, or groundwater, then it should be reported via the Environmental Agency’s website or via phone on 0800 80 70 60.

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