How to Dispose of Old Milk?

Milk is essential in most of our pantries. Most of us love to start the day with a cup of tea or coffee, and they always taste better with a dash of milk. But sometimes you open the fridge, pick up the carton of milk and you immediately feel like something is not right. The carton feels heavier on the side and it feels like solid clumps are floating about in the milk. 

You open the carton and your fears are all true, it’s gone bad. Milk does not have a very long shelf life once you open the carton. Fresh milk, which is usually sold in glass jars, is pasteurized and has a shelf-life of 2-3 days in the fridge. Ultra-heat treated milk that comes in tetra pack packaging lasts much longer, all the way up to a week if you live in a cold climate. 

But once in a while, you will inevitably end up with bad milk. Now your first instinct might be to simply pour it down the drain, but I would advise against it. Milk is not good for your pipes or the water system. 

Milk is a type of food that can ruin your pipes and harm the environment if it is not disposed of properly. So how do you get rid of old milk? This article will answer all your questions and will explain in detail what kind of environmental problems milk can create if it is not disposed of properly. 

How to Dispose of Old Milk?

The best way to get rid of spoiled milk is to compost it. If it is not an option you should contact your local waste disposal facility to ask about the details of what you should do. Different municipalities have different systems and you have to make sure your disposal method is in line with your municipality’s guidelines. 

You cannot flush any dairy down the drain. Whether it leads to the septic system, kitchen drain, or stormwater drain. Most states in the USA and the UK have outlawed pouring milk down the drain, a criminal offense for businesses. For households, you may not be legally responsible, but as citizens, you do have the responsibility to take care of your community and the environment. 

Milk is a level-3 animal by-product in the UK, which means it should be disposed of by contacting a licensed contractor in your area. 

In the USA, in most states, you have to contact your local municipal solid waste management system to find out how you should dispose of milk. But as a general guideline, you are to put the waste in a heavy, black garbage bag, dispose of it in the trash and let your local solid waste management know. 

Difference between old, spoiled milk and sour milk: 

Be very careful about the difference. Some websites call spoiled milk sour and vice versa, this is incorrect. Spoiled as the name would imply is inedible. 

Sour milk is still edible. The smell and taste are very different. Old milk can turn sour sometimes, but in most cases, it spoils, so be careful not to ingest spoiled milk. 

The bacteria that spoil milk is very different from the bacteria that turn milk sour. Lactobacillus turns milk sour, it is also known for making yogurt. 

The bacteria responsible for spoiling milk are pathogenic and when they digest milk they release enzymes and toxins into the milk that give it that putrid smell and taste. Pathogenic bacteria can cause illnesses in humans and should not be consumed. 

Compost the milk: 

Composting milk or milk products is not ideal, and the strong odors it generates deters most community composting facilities from accepting milk. But you should still definitely contact the composting facilities around you to check if any of them accept spoiled milk. 

If you have your composting bin, you can throw your milk in it as well. Just keep in mind that milk and other dairies give off very strong odors when composting. And they have a high water content which may cause leaks. 

To avoid these issues, mix the milk with dry, fibrous matter like shredded newspaper, or sawdust. Then bury the mixture at least 18 inches below the surface of the compost surface so the smell does not leak out. You can learn more about the details of how to compost milk from this link

Why is milk bad for the environment?

Milk is a product that has a high oxygen demand, which means the bacteria that break it down require a great deal of oxygen to decompose it. If milk is poured down the drain and ends up in local water bodies, it will likely cause algal bloom on the surface of the water which will deprive the aquatic plants of sunlight. 

Moreover, the bacteria in milk converts the organic nitrogen into inorganic nitrogen, this makes it very easy for the nitrogen to turn into ammonia.

The fat from the milk can form films on the water surface, and block oxygen from the air from diffusing into water. 

Overall, milk once released into the water source has disastrous consequences for aquatic life and is a major pollutant. Under no circumstances should it be disposed of into the drain. 


Milk is a type of food that can ruin your pipes and harm the environment if it is not disposed of properly. So how do you get rid of old milk? This article answers all your questions and explains in detail what kind of environmental problems milk can create if it is not disposed of properly. 

Frequently Asked Questions (FAQs): How to Dispose of Old Milk

Is it OK to pour old milk down the drain? 

No, do not pour milk down any drain, neither stormwater drain nor the kitchen sink. Milk has a high-fat content that will stick to the sides of the pipes and clog the pipes later down the line, moreover, milk when it is washed to a water source will consume a lot of oxygen while being digested by microbes, this creates a lack of oxygen for aquatic life and kills fish and other small animals. 

Should I throw away expired milk? 

It depends, the expiry date is set to a time a few weeks to a month before the actual expiry date. You should open the carton and see for yourself if it is consumable. Make sure you finish it quickly once you open it. 

What can I do with spoiled milk? 

You can hand it over to the solid waste management facility, contact a licensed contractor who can take it off your hand, or compost it. 

Can I pour old milk on plants? 

Yes, old milk is very good for plants, but you need to make sure you follow the rules, just dumping old milk on the soil will not be helpful. 

What happens when you pour old milk down the drain? 

The fat from the milk clogs up the pipes, it may also get washed into a water source where it may cause the production of ammonia, algal bloom, and cause fish to die by using up too much oxygen in its decomposition. 

Is milk good for the soil? 

Yes, it is. It contains high amounts of calcium and other nutrients the plants benefit from. It also breaks down quickly giving plants easy access to these nutrients. But you need to use it smartly, and follow certain rules while doing so. 

Can milk be composted? 

Yes, it can be composted. It is difficult, however, and proper protocol should be followed. Milk is mostly water so it adds an incredible amount of water to the compost. If you want to compost milk make sure you first mix it with sawdust or shredded newspaper to soak it up, this way you can keep your compost at the right consistency. 


  1. How to Dispose of Spoiled Milk. (2022). Retrieved 13 February 2022, from
  2. Find Out How To Dispose Of Spoiled Milk In An Eco-friendly Manner. – Thinking Sustainably. (2022). Retrieved 13 February 2022, from–can-you-flush-spoiled-milk-down-the-toilet-
  3. How do I dispose of spoiled milk?. (2022). Retrieved 13 February 2022, from
  4. Ruelas, G. (2022). How To Dispose Of Spoiled Milk? Do’s and Don’ts! – How to Dispose of. Retrieved 13 February 2022, from
  5. NPR Cookie Consent and Choices. (2022). Retrieved 13 February 2022, from
  6. You Should Never Dump Dairy Down The Drain. Here’s Why. (2022). Retrieved 13 February 2022, from
  7. (2022). Retrieved 13 February 2022, from
  8. Pouring Milk Down the Drain is a Criminal Offence for Businesses. (2022). Retrieved 13 February 2022, from
  9. Make the most of Milk – Recycle Devon. (2022). Retrieved 13 February 2022, from
  10. Dairy researchers identify bacterial spoilers in milk | Cornell Chronicle. (2022). Retrieved 13 February 2022, from

Leave a Comment