White Slime in Sink Drain: 9 Ways To Easily Fix It

Your sink drain is heaven for bacteria, mold, and other nasties to flourish and prosper. It’s damp. There are old pieces of food collecting in there. It’s their ideal environment.

One thing in particular that likes to appear in our drains is a kind of white slime, otherwise known as ‘bio slime’ or ‘biofilm.’ Not to be confused with regular mold, this slime is much more challenging to get rid of.

While technically, this biofilm is less hazardous to your health than regular mold, it’s still unsightly, smelly, and not exactly something you want hanging around your sink drains.

So in this article, we’ll look at what is causing this white slime to form and how to get rid of the stuff once and for all!

Why is there white slime in your sink drain?

Believe it or not, the bacteria that comprise this biofilm are already present in the air that we breathe and the water we drink. The difference is it’s in such low quantities it’s completely unnoticeable and inconsequential to our health.

However, when an area stays damp and has a food source nearby for a prolonged period, these micro bacteria and fungi can multiply, and more importantly, they like to stick around the edge of the pipes.

Once it’s stitched around the pipes, it’s tough to get rid of, as a generic household drain cleaner isn’t aggressive enough to get the job done.

This white slime is widespread in damp drain pipes, so don’t worry if this has happened to you. It’s not something you’ve done wrong. Here are the primary factors contributing to white biofilm forming in your drains.

Water presence

The number 1 reason this film starts to form in the first place is due to the presence of water. As water sits there for a prolonged period, it gives the micro bacteria and fungi a chance to propagate and attach to the drain lining.

This is why you’ll often see this film forming in places such as in a shower head, around taps, or even inside a dehumidifier.

It loves the damp, so whenever something stays moist for a long time – expect this white slime to follow.

Food source

It’s not just the presence of water that promotes biofilm growth. It also likes to have a source of ‘food’ nearby that it can consume to grow.

This is another reason drains are such a common place to see white slime because even if you try to throw leftovers on your plate into a trash bin beforehand, some small amounts of food will inevitably be made into the drain. This alone is enough to propagate the white slime.

However, an important thing to note is that when we say ‘food’ source, we don’t just mean food in the sense of things we might eat as humans. For bacteria and fungi, many other things can constitute food, even when they contain chemicals.

Example alternative ‘foods’ for white slime include:

  • Shampoo
  • Soap
  • Hairspray
  • Deodorants

So, in addition to the food you dispose of, be aware of what other products are making their way into your drain, as they may also be feeding the slime.


For white slime to get a foothold in your drain, it needs to attach itself to the sides of the pipe, and it’s pretty good at doing this, as you can probably tell from how resistant it is to being washed away with even boiling water.

One of the things that can contribute to or promote white slime growth in your drain pipe is the presence of limescale.

This provides the white slime with a rough surface to cling to, and you will notice it grows considerably faster on limescale than an ordinary smooth drain pipe.

Plumbing fixture materials

There are quite a few plumbing fixtures that are in use around our kitchen and bathroom sinks. Certain materials will tend to promote the growth of white slime more than others.

An excellent example of this is rubber washers which are in the taps, the biofilm will grow much faster on this kind of surface as opposed to a different material, such as a ceramic or silicone washer will help deter the growth of bio slime.

In-line filters and water softeners

It’s common to install an in-line filter or water-softening segment that your tap water will pass through before reaching the faucet.

As the water tends to sit in these filters for a long time, they can also help promote the growth of the white slime, which is then easily carried forward into your kitchen sink drains.

You shouldn’t avoid using these by any means, but making sure they are well maintained, so the slime doesn’t get a chance to propagate can help reduce the white slime in your sink drain.

How to remove white slime in your sink drain

Ultimately you still need to use your kitchen sink drain daily. It’s essentially impossible to avoid the presence of food and water without simply never using the drain.

But don’t worry. There are plenty of methods to moth remove a high buildup of white slime and prevent it from coming back in the future.

1. Removing it with a cleaning product

One of the reasons why people have so much trouble getting rid of biofilm is that it’s often resilient enough to withstand essential cleaners such as a standard disinfectant spray.

Here you need to kill the bacteria and remove it from the drain pipe. A mild bleach or other product such as Bioclean does an excellent job at this, and if you’re able to get something down into the drain to give it a good scrub, too, that will help!

However, just removing the slime buildup is only the first step. There are other measures you can put in place to help prevent it from coming back.

2. Lower the amount of available food

As we mentioned, ‘real’ food is not the only food source for biofilm. Shampoo, soaps, hairspray, deodorants – you name it are all types of food that white lime will feed off of to grow.

Knowing what you put down the drain and flushing it down with water or a mild cleaner can go a long way to making the environment more inhospitable for bacteria and fungal growth.

3. Low the amount of water

On the flip side, sometimes it can work out better to not always ‘chase’ something down the drain with hot water if you don’t immediately need to.

This will often work against the natural instinctual thought of “I need to wash this food down the drain with hot water, or it will get moldy.” Usually, not using water and keeping the drain bone dry is better to dissuade bacteria growth.

4. Ventilation

Fresh air is not suitable for mold and bacteria in the air. They like it to be stagnant, humid, and muggy to propagate.

So if you’ve taken a hot shower in the bathroom, or boiled a lot of water in the kitchen, try to aerate the room and keep a nice fresh supply of air circulating the kitchen. This will also play a role in reducing bacterial and fungi growth.

5. Dehumidify

Similarly, suppose you naturally live in a place with high temperatures and humidity. In that case, you will no doubt be running into problems with biofilm as they love this kind of environment.

Consider purchasing a dehumidifier to help keep the humidity around the kitchen low and further dissuade biofilm growth.

6. Clean regularly

Bleach is usually your first port of call when removing a pre-existing white slime buildup. However, you don’t want to bleach your drain pipe every day.

So make sure you keep up with cleaning the drain line by remembering to spray a little bit of cleaner regularly to keep things friendly. More mild sprays that contain bleach, such as Chlorox, work well for this too.

7. Change plumbing fixtures

Certain plumbing fixtures, such as rubber washers or other materials, tend to promote white slime growth.

You can consider swapping to many alternative materials, which are far less hospitable to bacteria. These can include things like

  • Silicone rubber
  • Neoprene rubber
  • Neoprene sponge
  • Ceramic
  • Cork

Of course, the materials available for each component will depend mainly on what you’re swapping out. Research what’s available and swap things out where you can.

8. Remove limescale

White slime loves to use limescale-coated drain pipes to grip and grow much faster than average. So, removing the limescale makes it much harder for the bio slime to take root and easier to clean.

To remove the limescale, you can use a solution of sodium bicarbonate (baking soda), clear/ white vinegar, and some regular cleaning product to loosen the limescale, which can then be easily scrubbed away.

9. Copper line

You have to be careful not to clog your drain line with it, but copper has many antibacterial properties and can kill certain viruses.

Any copper in your kitchen drain will make it difficult for white slime to grow. So try introducing a bit of wound-up copper line, and you may need to clean the drain less often!

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