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How to Dispose of Spoiled Milk

When life gives you spoiled milk, dispose of it properly. Here’s what to do, and what to avoid.

Spoiled milk. It’s one of those problems that don’t go away by themselves if you ignore them. The question is, what should you do about it?

Let’s start with what you shouldn’t do. Don’t pour spoiled milk down the drain or flush it down the toilet. Not only can it clog your pipes, but it can also harm the environment in ways you never imagined.

In this post, we will talk about why that is, and what your best options for disposing of spoiled milk, in a way that doesn’t destroy the environment or your plumbing, are.

Milk Is a Bigger Pollutant Than You Think

Milk contains bacteria that feed on oxygen, European recycling and waste management company DS Smith writes in a post on its corporate blog, which is otherwise consumed by fish and other creatures in the water. So, when you pour milk into a body of water, you are basically helping to suffocate aquatic life. Yikes!

It turns out that milk is one of the biggest common pollutants in terms of the amount of oxygen consumed by the bacteria that it contains—called Biochemical Oxygen Demand (BOD)—bigger than pig slurry, cattle slurry, and raw sewage.

Think I’m exaggerating?

A study of milk wastewater published in the ScientificWorldJournal called dairy wastewater “of great concern due to the presence of high nitrogenous load.”

That’s nitrogen in the water that causes algae to grow in the lakes, clog water intakes, and block light in the water, killing the creatures that live on the bottom and making our waters unfit for fishing, swimming, and boating (United States Geological Survey).

Perhaps that’s why it is against federal and most state environmental regulations to dispose of milk in surface waters, as the Texas Animal Manure Management Issues (TAMMI) group at Texas A&M College explains on its website.

Even if you care little about the environment, you should care about the fact that it can clog your pipes, big time.

Can You Pour Spoiled Milk Down the Drain?

Don’t pour spoiled milk down the drain. It can clog the plumbing in your house or apartment building.

A reader from Florida emailed us to say she reached out to her local utility—and they told her that milk products are a main culprit contributing to sewage and drain line backups in their system.

The fat and protein, the utility had told her, can cling to the pipes like glue, collecting other things and causing blockages.

In other words, if pouring spoiled milk down the drain doesn’t clog the pipes in your home, it might as well clog the sewage in your neighborhood.

As we’ve already established, it also pollutes the environment, which is why, in the United Kingdom as well as in some U.S. states, it’s illegal for businesses to dispose of milk by pouring it down the drain.

Can You Flush Spoiled Milk Down the Toilet?

Don’t flush spoiled milk down the toilet. Just as it can clog the drain in your kitchen, it can trigger an emergency visit from the plumber in your toilet.

How to Dispose of Spoiled Milk

According to Permaculture, using milk in your compost or garden can create healthy soil. The nutrients that make milk good for us humans—namely, amino acids, carbohydrates, proteins, and enzymes—can also nourish healthy microbes and fungi in the soil, the magazine writes.

Tehrene Firman of Well + Good recommends mixing a 50/50 solution of milk and water, and either spraying your plants’ leaves with it or pouring it lightly around the base of the plants as a fertilizer.

But don’t use too much, Kerry Michaels warns The Spruce readers. Watering or spraying plants with too much milk can result in wilted growth or, even worse, a spoiled plant due to the bacteria contained in it.

Another reader emailed us to say that there’s a compost group in her area and, after connecting to them to ask about expired condensed milk, they had told her that they do accept it. So, for eco-friendly disposal of milk products, we recommend that you do as her and look for compost groups and collectives in your area and call them.

In the comments to a post on the Anchorage Water and Wastewater Utility’s Facebook page, an Anchorage, AK, resident asks what she should do with spoiled milk. The answer is, “I personally use an old can to put fats, oils, and grease in, and freeze it until trash day, then throw it in my trash can.”

As a last resort, and if you don’t happen to have a garden, you can double-wrap the milk in plastic bags and throw it in the trash. The drawback to this method is that you can’t recycle the carton.

Never put cartons full of spoiled milk in the recycling bin.

Can Spoiled Milk Make You Sick?

There are two types of bacteria that grow on our food: those that make it spoil and those that cause food poisoning. While the former alter the aroma, taste, and texture of the food, the latter are stealthy and cannot be detected by our senses.

The milk that we drink is pasteurized. But, as the good folks at the Missouri Poison Center point out, the pasteurization process doesn’t kill all the bacteria. And if there’s one thing that bacteria are good at, it’s replicating, very quickly at room temperature and slowly in the fridge.

The Centers for Disease Control and Prevention (CDC) estimate that 48 million people contract food poisoning every year. To put the numbers into perspective, that’s 1 in 7 Americans. Of them, 128,000 get hospitalized and 3,000 die.

Mild cases of food poisoning, the CDC reports, can give you nausea, stomach cramps, upset stomach, diarrhea, and vomiting; severe cases can lead to chronic arthritis, brain and nerve damage, and even kidney failure.

Can You Cook With Spoiled Milk?

It isn’t a good idea to cook with spoiled milk because you have no way to determine if it’s safe to eat or not.

If the milk is overgrown with pathogenic bacteria, heating or cooking with it won’t make it any safer to eat. While it’s true that the high heat kills the bacteria in the milk, it doesn’t inactivate the poisonous toxins that they left behind in it.

As Consumer Reports… err, reports, experts say that cooking with spoiled milk is probably not worth the risk.

Safety should always come first when it comes to the health of you and your loved ones. As the cook and the main person responsible for what goes into the refrigerator—and what stays there—the burden of that safety rests largely on your shoulders.

In Conclusion

Spoiled milk is a bigger polluter than most people think, and there are not that many ways to get rid of it. Use it in the garden or throw it in the trash, but never pour it down the drain, flush it down the toilet, or put it in the recycling bin.

Editor’s note: This article was first published on December 28, 2021, and mentioned the two options of pouring the milk down the drain or pouring it down the drain as acceptable. Thanks to feedback from our readers, we revised it on June 22, 2022, to give better advice.

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Jim is the former editor of Home Cook World. He is a career food writer who's been cooking and baking at home ever since he could see over the counter and put a chair by the stove.