10 Things You Should Never Put Down the Drain

kitchen sink

Story at-a-glance -

  • Most of the plumbing in your home is out of sight, beneath your sink or behind walls; however, these bits of pipe can be costly when not cared
  • Specific items down your drain may increase pollution and costly plumbing repairs, such as grease, flushable cat litter, paper towels and coffee grounds
  • Not only will you make a significant difference to your plumbing when you stop using it incorrectly, but there are simple ways to keep those pipes draining smoothly without harsh chemicals

By Dr. Mercola

Your kitchen sink consistently rates as one of the dirtiest places in your home. According to NSF International, a public health and safety organization, your dishrag and kitchen sink top the list of places in your home with the most germs.1

Even worse than the bathroom or toilet seat, your sink is the ideal place for illness-causing microbes to thrive.

Your kitchen sink may be a source of frustration when it becomes clogged, or may be an area through which you inadvertently are polluting the environment. The plumbing in your home may seem like a mystery since it's usually hidden behind walls and under the sink.

However, once you understand how it works in your home, and how it's treated when it leaves your house, you'll have a greater ability to maintain your plumbing pipes and reduce your impact on environmental pollution.

How Plumbing Works

The plumbing in your home is a little like the arteries and veins that transport nutrients and oxygen around your body.

The term plumbing is actually used to describe any system that moves fluids from one area to another. Plumbing may be used for sanitation, heating and cooling and water supply, but isn't limited to those functions.

In your home, most of your plumbing pipes are located under your sinks or in your walls as they transport wastewater out of your home and deliver drinking water into the house. Fluid is transported using a system of pipes, fittings and tanks, any of which may become obstructed with bits of whatever is going down your drain.

Plumbing follows the laws of gravity, and has two subsystems that don't cross. One delivers clean water and the other transports wastewater out. When water enters your home, it's under pressure. As it exits, water drains through pipes that are angled downward.2

When the pipes become caked with grease, bits of food or other objects, it impedes the flow of water out of your home.

This is what happened in the city of Madison, Mississippi, where Canton Municipal Utilities (CMU) officials claim the DeBeukelaer cookie company was washing excess cookie dough down the drain when cleaning the equipment at their cookie factory.3

CMU General Manager Kenny Jones said the corporation denied the problem was on their end, but also said they were often at the plant to address poor drainage and had photos of cookie dough settled on the bottom of the plumbing lines.4

CMU commissioners have given Jones and an attorney the task of mediating a resolution to the disposal of the dough that won't impact the lines. The cookie company wasn't just dumping waste down the line, but rather cleaning their equipment prior to being stored for the evening.

The same thing may happen in your own home as you clean your dishes after dinner or wash equipment from doing a hobby or craft. The extra bits of food, grease, chemicals and compounds are flushed down the drain.

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Don't Flush These Items Down the Drain

As what you put down your drain has an impact on both plumbing in your home and the environment, it's important to understand how your plumbing works and how to reduce damage done to your own property and the environment.

You may accomplish these goals by never putting the following items down your drain. And you may reduce your financial risk, as plumbing repairs can be costly.


Grease sticks to the inside of your sewer pipes, both on your property and in the street. Over time it can block the entire pipe. Instead, scrape grease into the trash.

Any oils are a major contributor to drain clogs, which includes mayonnaise, salad dressing, butter, cooking oils and fats from cooking meats, such as bacon, beef and pork.5 Motor oil and transmission fluid shouldn't go down your sink drain or toilet either.

Egg Shells

Egg shells are composed of a hard outer shell and a thin membranous inner layer. The shells are hard on the blades of your garbage disposal, reducing the overall life of the appliance.

The thin membranous layer may wrap around the grinding apparatus and slow the motor until it burns out. The shells may compound the development of other blockages.

Coffee Grounds

These don't harm your garbage disposal and may help absorb odors, but they do accumulate in your pipes and increase the risk you'll experience a clogged drain.6 Coffee grounds do make an excellent addition to your compost pile.

Expandable Foods

Foods like pasta and rice continue to expand as they soak in residual water in your garbage disposal and drain pipes. Pastas are often made with semolina flour, which becomes sticky and easily gums up your pipes.7


Have you mixed flour and water together? Basically, this produces glue, sticking to the sides of the drain pipes and capturing any other little bits of garbage along the way. This is essentially the problem Madison County is facing after disposal of cookie dough from the cookie company in town.

Produce Stickers

You wouldn't think of using your sink to dispose of your grocery list, but those produce stickers often fall off when you're washing fruits and vegetables.

They often include bits of plastic and are coated with adhesive, neither of which are water-soluble. They may be caught in grease coating your drains, get caught in pumps and hoses or block the screens and filters at your water treatment plant.

Paper Products

Toilet paper is developed to eventually break apart in water. Other paper products do not break apart after being flushed down the toilet or after going through the garbage disposal in your sink. Products like paper towels, feminine hygiene products and cotton balls should go into your garbage can instead.  

Each of these items have a high absorbency rate, making them perfect for clogging your pipes.8

Biodegradable or 'Flushable' Products

Many of the products advertised as flushable or biodegradable may meet specific standards for the term, but often increase your risk of drain clogs.

For instance, flushable cat litter continues to be highly absorbent in the drain. Cat feces may carry the parasite that causes toxoplasmosis, which is not destroyed in water treatment and is a threat to marine animals.

Wet wipes are another serious problem in your sewer drain. They don't disintegrate properly and often combine with other products to produce a large super-knot. New York City has spent more than $18 million in five years to repair equipment problems triggered by so-called "flushable wipes."9

Paint and Cleaning Products

While they are in liquid form, these products both increase your risk of developing a drain clog and pollute the environment. Your city will have different requirements for latex and oil paint, so it's important to get that information from your municipality.10

Conventional cleaning products often contain phosphates, antibacterial agents and other compounds that don't often get removed at your water treatment plant. Instead, make your own cleaning products at home with environmentally safe vinegar, baking soda and essential oils.11


It might seem logical to flush your expired or unused medication down the toilet or crush it in your garbage disposal, but research demonstrates that a high number of those medications do not get removed at your local wastewater treatment plant and then enter the environment.

Even your tap water likely has a small amount of medication you're drinking every day, as neither wastewater treatment nor clean water treatment before it gets delivered to your home is able to remove medications.12

Keep Your Garbage Disposal Running Efficiently

Almost all of the items mentioned above have the potential to damage your garbage disposal unit as well as clog your drains. You can increase the life of your disposal and reduce any odor emanating from your sink by making these changes:13,14

  • Keep it clean. By keeping the disposal clean you'll reduce smell in your home, reduce the growth of germs in your sink and extend the life of your unit. Pour some dish soap down the garbage disposal and run it with cold water for a minute or two each night after washing the dishes. The consistent use of a product that breaks down grease will also help remove clogs.
  • Prevent jams in the disposal. Cut up larger pieces of food, run the disposal consistently and don't jam the disposal with food before running it will all help the unit to run more effectively.
  • Use cold water. Running the disposal with cold water keeps the motor cool during use and congeals any grease that may have made it down the drain. This will help solidify the grease and get it chopped up before running down the pipes. Run water for about a minute after running the disposal that had food particles so the refuse can reach the street pipes.
  • Run it regularly. Running your disposal regularly will prevent the buildup of rust and corrosion on the parts and your disposal running well.

What Happens When Water Leaves Your Home?

While the environment has an amazing ability to reduce small amounts of water waste, sewage from human use must be treated before being released into the environment as there are billions of gallons which would overwhelm nature.15 When not properly cleaned, water may carry bacteria, disrupting the health and growth of fish, plants and marine life.

The process of treating wastewater goes through three steps. First a mechanical treatment is used to remove solid waste products that are suspended in the water. A screen is used to remove solid objects and then the water is allowed to settle and sedimentation is removed. Although it's referred to as a mechanical removal, many times chemicals are added to speed the sedimentation rate.16

The second part of the process is biological, and designed to remove organic material dissolved in the water that escaped the mechanical treatment. This is followed by another pass through the sedimentation tank. The third step is much like the second, followed by disinfection with chlorine if the water is not being released into the environment.17 While chlorine is effective in killing organic matter and preventing the spread of disease, it carries additional risk.

When chlorine comes in contact with organic carbon-based objects, like plant material, it produces disinfection byproducts which are hundreds of times more dangerous to your health than the original chlorine.18

Keep the Pipes Clean

Keeping the pipes in your home clean is easier and less expensive than treating a problem later. In this demonstration video you'll learn how to remove a clog from the pipes under your sink. Following the strategies outlined above will help prevent a clog. There are also a few things you can do to clean your pipes without chemicals, reducing the risk of a buildup over time.

Bathroom sinks are notoriously slow as most people rinse the results of shaving down the drain with shaving cream or other products used to prevent nicks and cuts to the skin. Kitchen sinks may also benefit from some preventive maintenance.

Use a mix of white vinegar and warm water in your sink once a week to keep your drains clear. Fill the sink with the water and vinegar mix and release the water. The combination of vinegar and pressure from a full sink helps to flush your pipes. If this isn't enough you may pour several tablespoons of baking soda down the drain followed by white vinegar. Let this sit for up to an hour or more and then fill the sink with hot water and then release it to flow out all at once.

Reduce buildup of sediment in your hot water heater and shower head. Remove the shower head and soak it in white vinegar every six months. This may also improve your water pressure. Draining your hot water heater and removing sediment every six months may improve efficiency, improve the life of the appliance and reduce the amount of sediment that drains down your pipes.