If you work on your car from time to time, proper disposal of automotive chemicals is a definite priority. Should leakage occur, it’s only natural to wonder the effects, so with that in mind, does brake fluid kill plants?
Where plants are concerned, brake fluid is probably the most toxic automotive fluid there is and will definitely kill your plants. In one study, comparing the effects of different fluids on plant life, brake fluid was the worst, with antifreeze being a close second, and automatic transmission fluid taking 3rd place in toxicity to plants.
In today’s article we’re going to explore the question in a little more detail, so that you’ll know why it’s so toxic to plants, what effects occur with exposure, what brake fluid does to grass, and it’s overall environmental impact. Read on and we’ll tell you all about it!
Why Does Brake Fluid Kill Plants?
Brake fluid is toxic largely due to the diethylene glycol that is present in its composition. This chemical, which is used most often with polyester resins and for making plasticizers, can do a lot of damage when enough of it is spilled on a plant.
It can also get into the soil, so that it becomes contaminated and will not be fit for growing plants until it has been sufficiently diluted or otherwise dispersed. As such, you’ll need to be very careful with how you dispose of brake fluid – the stuff is definitely deadly to plants.
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What Is the Effect of Brake Fluid on Plants?
In the study that we mentioned in the opening of this article, various automotive fluids were tested in order to determine the potential effects of a fluid spray following an automobile accident in regards to plant life.
Brake fluid was found to have the worst effects, often killing the plants in as little as 4-days time, and basically reducing them to what was described as ‘a thin, ‘almost-spiderweb’ string’.
Another study provides a little more information as to why this is the case, by focusing on the primary brake fluid ingredient diethylene glycol. Plants that were exposed to this chemical first experienced an enormous decline in their ability to process water. This resulted in chlorosis, wilting, and eventual necrosis of plant tissue.
The LD50, which is a term used to describe an amount that was fatal to approximately half of the plants (lethal dose 50%), was found to be 6238 milligrams, but you need to keep in mind that this was an experiment to see if plants could help decontaminate a large wastewater area on a construction site.
So even in very small amounts, a brake fluid spillage has a very high chance of killing the plants that it is spilled on and contaminating the soil against new growth until it may be properly cleaned or otherwise diluted.
What Does Brake Fluid Do to Grass?

Brake fluid, when spilled on grass, is likely to kill the grass within 2 – 4 days and will also contaminate the soil. This means that you will not simply be able to reseed the contaminated patch.
Your best approach would be to dig up the affected area in order to dispose of the dirt as you would any hazardous waste.
By replacing the soil, this helps to ensure that rains do not come and further contaminate the soil and you can also immediately reseed the patch or transplant new grass in its place.
While it seems a bit extreme, replacing the soil is really your best option – diethylene glycol is quite toxic and once it’s in the soil, it is extremely difficult to properly clean it out to make it fertile again.
Is Brake Fluid Bad for the Environment?
Yes. Brake fluid is bad for the environment due to its toxicity to plant and animal life when it is spilled. As it is necessary for proper brake function, it is good to know how to dispose of it safely and properly.
The best thing to do with brake fluid that you are disposing of is to take advantage of the absorbent qualities of kitty litter. Get a large metal tray and fill it so that there is an even ½ inch of kitty litter inside and then you’ll want to pour the old brake fluid into the litter.
After that, you’ll want to leave the pan sitting out for a period of 3 to 4 days, until it is fully absorbed into the litter.
This should basically ‘clump’ it up in sections, so that you can scoop it up into trash bags and then dispose of it in accordance with your local laws.
Another easy alternative is to take it to a local recycling center or to an automotive body shop and they may also be able to assist you, although the latter option may charge a modest fee for proper disposal.
The ‘auto body’ method is often the best route to take, as they will be familiar with proper disposal laws and much better equipped to comply with them.
As toxic as brake fluid really is, proper disposal is an excellent habit to get into, and it will also help you to avoid any expensive fees or damages caused by an accidental spillage or improper disposal methods.
Final Thoughts
Today we’ve answered the question ‘does brake fluid kill plants’ and the answer is a definitive ‘yes’. Brake fluid contains chemicals that can quickly kill plant life and contaminate the soil, with diethylene glycol being the primary culprit.
When it is spilled on plants, they cannot process water, and wilting, chlorosis, and necrosis will soon occur, all while the brake fluid soaks deeper into the soil and prevents replanting without completely removing it.
With proper disposal habits, you can help to reduce the chances of spillage, and this may be done with kitty litter or even a trip to the local body shop. While brake fluid is currently a ‘necessary evil’, responsible disposal can definitely help to reduce the environmental impact until a more eco-friendly replacement becomes available!