Water is supposed to be crystal clear, not only from side to side but also from top to bottom. So why do you see a rainbow on the top of your water caused by an oily film?
Why Is My Water Oily? An oily film in your water may be caused by fuel or oil spills, animal fats, blacktop road oil runoff, decomposing organic material, naturally occurring hydrogen sulfide, iron bacteria, or oil leaking from your well-water pump.
Since oil, fuels, petroleum-based lubricants, and other oily substances are all around us, sometimes it is hard to tell one from another. If you are experiencing an oily film on top of your water, here are the most likely causes.
Reasons why you have an oily film on top of your water.
Oil or fuel leaking from a storage tank or mechanical device:
Oil or fuel is usually safe and secure when stored in a proper storage tank. But even a quality storage tank will weaken as it ages. Often a leak will occur at an opening or a seam of the tank, and sometimes a leak will develop where a leg or support for the tank is attached.
Oil tanks that are buried beneath the ground can pose a serious problem when a seam separates or any major leak develops.
The fuel in a buried storage tank can leak for years before the problem is discovered. By the time the problem becomes apparent, there could be enough fuel loss to saturate the ground and contaminate a water well for many years to come.
An old car, truck, lawnmower, or any other type of machine that has an engine could have fuel and oil left in them which can eventually work its way into the earth, and then into your well water supply.
Even a fuel leak miles away can make its way into the water that ends up in your well.
Decomposing animal fats containing high levels of oils:
Wild animals are all around us! And of course, wild animals don’t live forever. Sometimes when an animal passes away, their body fat will break down and end up in shallow water supplies.
This sounds a little unpleasant, and it is! But it is simply the way nature works. The oils left in your water supply from animal fats will generally not be harmful when consumed, but it may add an odd smell to the water which some people might find undesirable.
Decomposing plant life:
We use oils made from plants all the time. Corn, vegetable and sunflower oils are just a few of the types of oils that can come from common plants.
All kinds of plants have oil in them, and this oil can get in groundwater that will make its way into your well. Water traveling under fields or farms can pick-up plant oils as it passes.
This oil is not considered to be harmful, and should not cause any problems with your plumbing, or water fixtures. But it may settle on the top of your water when you pour yourself a glass of water.
Iron Bacteria:
Iron bacteria in water consume iron that is present in the water. If the iron in the water also contains minerals like limonite or hematite, the iron bacteria will cause the minerals to dissolve in the water.
These minerals will stay dissolved in the water when they are in an enclosed space, like the plumbing of your home.
But when these minerals come out of your faucet and become exposed to air, these fine minerals will come out of the water and settle on the surface of the water, giving it an oily look.
Hydrogen Sulfide:
Hydrogen sulfide is most commonly known for its unpleasant rotten egg odor when it is found in water. Hydrogen sulfide is a gas that comes from sulfide reducing bacteria that can be found in water that has been exposed to decaying organic material.
Most of the time, hydrogen sulfide levels are minimal, only causing a rotten egg smell, and little else.
But at moderate to high levels, hydrogen sulfide can cause odd tastes in the water and black discoloration on the water fixtures in your home.
Hydrogen sulfide also contains a small amount of oil which can become noticeable on the surface of the water.
This oil is often not noticed during regular use of your water because it is often so minimal, that soap and detergents eliminate it before it is discovered.
Oil leaking from your well water pump:
The pump in your well is submerged in water 24 hours a day, 7 days a week. Because it contains moving mechanical parts, they require oil to keep them lubricated so they can operate properly.
A well water pump is sealed tight to keep the oil in and the water out. But sometimes the seals of the pump can fail and allow the oil from inside of the pump to slowly seep out.
Naturally, this oil will end up in your well water. Often, if you notice an oily film on the surface of your water practically overnight, it is caused by the well water pump seals failing.
These are the most common causes of an oily film on the surface of your water, but if you have other appliances that interact with your water, they could also introduce oil or grease to your water.
To resolve this oily water problem, a whole house filter may be installed to capture incoming oily substances and other impurities in the water.
If the oily substance is due to sulfur bacteria, or iron bacteria, a backwashing carbon filter should do the trick.
My well water in kerala is showing white oily substance for the past 15 days. we have given the water for testing at 3 places and awaiting the result. Is there any particular reason for this sudden change in my wll water which was clear all these years.
Hello Sonia and thank you for the question.
Without actually being there to see the oily substance, it is impossible for me to give a proper analysis of what it might be but if you have a well, it could be oil leaking from your submerged well pump inside of the well.
If you have municipal water, you should contact your municipal water provider and report the problem immediately.
Unfortunately, you probably have to wait for the test results to come back. Make sure you ask the laboratory any questions that you may have about the substance.
I hope this was helpful.
Paul