rusty dirty water pours from the tap into a glass

Why Is My Tap Water a Strange Color?

Turning on your water tap and expecting clean, clear water to come out only to see a rainbow color can be puzzling.  While they may look unappealing to drink, some colored waters are harmless and pose little potential for issues while others are dangerous and toxic. Check out our guide to different colored tap waters which discloses the causes, implications, and easiest ways to fix colored water coming out of your faucets.

Pile of potassium permanganate crystals and glass a water on a wooden table

Potassium permanganate is used extensively in the water treatment industry.

Pink or Purple Tap Water Caused by Potassium Permanganate

In 2017, residents from the town of Onoway, Alberta, Canada, woke up to a surprise from their water taps: bright pink water.  This unexpected surprise would make just about anyone concerned about the safety of their water. The culprit, potassium permanganate, is a chemical compound that’s added to just about every purified drinking water supply, including well water, within the United States.

The Purpose of Potassium Permanganate

Potassium Permanganate is used during the pretreatment processes of purification.  Its purposes include:

  • Controlling bad odors
  • Removing colors
  • Removing certain contaminants
  • Limiting the formation of disinfection byproducts (DBPs)
  • Controlling iron bacterial growth in wells

During pretreatment, potassium permanganate first manages the smell and color of the water to make them more appealing.  Then, it oxidizes contaminants including iron, manganese, sulfides, and other toxic compounds.  Oxidizing the contaminants forms them into larger particles which makes them easier to be removed from the water during filtration.

Why Potassium Permanganate Turns Water Pink

While potassium permanganate usually goes unseen in your tap water, it can cause it to turn pink when certain problems hit either your municipal water supply or well including:

  • Water treatment system mechanical problems
  • Improper dosing

First off, if your city or well water purification system breaks down, potassium permanganate could be released in excessive quantities into the water causing it to turn pink.  Second, potassium permanganate needs to be regularly re-supplied to a water purification system; if the wrong dose is added, then an excessive (or insufficient) quantity could slip into the water supply and cause it to turn pink  Even very small amounts of excessive potassium permanganate can cause water to turn pink.

Not only can potassium permanganate cause water to turn pink, but it can also turn it purple. Similar to the incident in Canada, in 2019 the people from the town of Coal Grove, Ohio awoke to purple, not pink, water coming from their faucets.  According to the city, it was the result of a water pump malfunction in which an excessive amount of potassium permanganate was dumped into the water system.  On this occasion, the compound made the water look more purple than pink.  If you see purple coming out of your taps, the most likely culprit is potassium permanganate.  

Safety and Problems Caused by Potassium Permanganate 

Whether you’ve ever heard of it before or not, you most likely already have potassium permanganate flowing through your home’s water system.  The plus side of this is that it helps manage the contamination levels in your water.  On the downside, when it’s added in excessive quantities, then it has the potential to cause problems including health risks.  Side effects of too much potassium permanganate include:

  • Skin irritation and burning
  • Pink stains in sinks and bathtubs

Potassium permanganate is considered an acute contaminant, meaning that it doesn’t pose any immediate risks to your health.  Therefore, you shouldn’t generally worry about the safety of the compound in your water.  But, if you have sensitive skin conditions such as eczema or psoriasis, then you should steer clear of water high in potassium permanganate as it can cause increased irritation to already sensitive areas.

Potassium Permanganate

What to Do if Your Water Turns Pink From Potassium Permanganate 

If your water randomly turns pink, then you shouldn’t be too worried; most likely, your city is already aware of the issue and on to fixing it.  If you rely on well water, then call a plumber to come and fix issues related to your well’s purification system. Avoid drinking the water until it returns to its normal color.  Run your taps every so often until the pink has gone away.  Once the pink is gone, then you can resume drinking, cleaning, and bathing in the water.

Pink Water Caused by Serratia Marcescens

A second cause for pink water is Serratia marcescens, a species of Serratia pathogenic bacteria that occurs naturally in water and soil.  In room temperature water, it causes a pinkish red pigment.  When water is not properly decontaminated, the pathogen can cause different infections, although it is not particularly dangerous to most people. In addition to pigmentation in water, the bacteria have the ability to survive on surfaces and toilet bowls forming what looks like a sludgy, pink slime.  You’re more likely to see the pigmentation on moist surfaces than you are in your drinking water.

What is Serratia Marcescens

Serratia Marcescens is an airborne bacteria implicated in numerous infectious diseases.  It loves damp places in your home including your bathroom and kitchen surfaces.  Generally, any surface in a moist environment where phosphorus and/or fatty substances are found is a typical place where you’ll find the bacteria.

Because the bacteria is airborne, it spreads very quickly and can easily jump from one surface to another.  It has also become more common in recent years as more people make the choice to not chlorinate their water or use chlorine bleach to clean their homes.  Those who do use chlorine in their water system and for cleaning are less likely to see outbreaks of the bacteria.

Safety of Serratia Marcescens

Despite the fact that Serratia bacteria is implicated in many different infections, it poses little to no harm to most individuals.  For those with compromised immune systems, the bacteria could be more harmful. Some of the diseases implicated by the bacteria include:

  • Pneumonia
  • Lower respiratory infections
  • Urinary tract infections
  • Bloodstream infections
  • Meningitis

What to do if Your Water Turns Pink From Serratia Marcescens

If pops of red or pink pigment or slime start showing up in your toilet water or surfaces, don’t be too alarmed.  You can clean the slime off yourself without the help of a professional. To clean infected surfaces, scrub with an abrasive cleaning tool and apply chlorine bleach to the surface.  Allow the bleach to rest for 10 to 20 minutes before wiping the surface down. 

To clean infected toilets, add ¼ cup of chlorine bleach to your toilet tank and scrub your toilet with an abrasive toilet brush and chlorine bleach.  Allow the bleach to sit in the toilet for 15 minutes before flushing.  To prevent the bacteria from forming in the first place, be sure to regularly clean off and dry your bathroom surfaces and always flush your toilet after use.

Green Tap Water Caused by Algae or Copper

There are two likely causes for green or greenish-blue water coming out of your faucet: 

  1. Algae buildup in the water system
  2. Corrosion of copper pipes

Unlike potassium permanganate, neither algae nor copper are added to your water supply and are toxic to humans.  If you see a green or greenish-blue color coming out of your faucets, then you should stop drinking the water immediately.

Causes of Algae Buildup and Copper Pipe Corrosion

The first most likely cause of green tap water is algae buildup in your home’s water system.  It’ll most likely be found in your water or toilet tank.  If you have a rainwater storage tank, then your tank is especially prone to algae buildup. Algae are tiny organisms that contain chlorophyll, a green pigment that makes plants and leaves green. 

Chlorophyll grows through the process of photosynthesis in which it absorbs light energy, carbon dioxide, and water. So, in order to prevent algae from growing, you’ll need to ensure that your water tank is completely opaque so that no light can get through.  You can also add small amounts of chlorine bleach to your water system in order to kill algae before it grows out of hand.

The second most likely cause of green tap water is the corrosion of your home or water treatment plant’s pipes.  Corrosion is the deterioration of your pipes so much so that the metal material of the pipes begins to dissolve into the water flowing through them.  Pipe corrosion is caused by:

  • High or low water wpH levels
  • Buildup of bacteria, minerals, or chemicals
  • High water velocity

So, when copper pipes corrode, tiny pieces of copper make it into your home’s water supply and can cause it to change color.   

Safety of Algae and Copper in Water

If your water begins to turn blue or bluish-green, you should immediately stop drinking it.  Algae and copper can cause both mild and dangerous health issues. To begin with, some types of algae are highly toxic and you should avoid any type of contact with them.  Do not drink, bathe in, or even wash your clothes or dishes in water that you know is contaminated with algae.  Mild health problems caused by algae include:

  • Fever
  • Vomiting
  • Skin irritation

Some more serious, long-term health problems caused by consuming toxic algae include:

Another important note: Be sure that your household pets do not consume algae-contaminated water as it has the potential to cause severe and life-threatening illnesses in animals.

Copper contamination poses perhaps an even worse safety threat than algae.  It is one of the most dangerous contaminants in water today.  Mild health effects of copper contamination in water include:

  • Nausea and vomiting
  • Headaches
  • Stomach cramps

Serious, long term effects of copper contamination include:

  • Liver damage
  • Kidney diseases
  • Developmental problems in children

For people with certain medical conditions, long-term exposure to copper-contaminated water can cause copper toxicity or poisoning.  Cancer or Wilson’s disease are just two of the conditions that increase one’s vulnerability to copper toxicity. 

What To Do if Your Water Turns Blue

If you believe that your water is turning green due to algae or copper, immediately stop using the water and call a plumber.  The plumber will be able to locate either the algae in your home’s water tank or corrosion in your pipes.  If there is no corrosion in your home’s pipes, then your city’s water line may be degenerating.  In this case, call your city immediately.

Only once you’ve addressed and fixed the blue coloring concerns in your water can you drink it again.  Allow your water to run for 30 to 60 seconds before using and run a toxicity test on it to ensure it is safe. To prevent algae or copper contamination in the first place, have your home’s water tank and piping system inspected regularly.

Dirty dark gray running water falling into a sink from tap

Black water coming out of pipes and faucets is pretty common in old houses.

Black Tap Water From Faucet

Black water is the exact opposite of what many people would expect to come out of their faucets.  However, it is not all that uncommon to occur as black water can be caused by a handful of different culprits.  Some of the causes of black water include:

  • Mineral deposits
  • Outdated pipes or water systems

Although it may look frightening, black water caused by either of these culprits isn’t usually exceedingly harmful.  However, in order to properly diagnose the cause of the black water, it’s best to seek out the help of a plumber or call your municipal water supplier before drinking or using the water.

Black Water Caused by Minerals

The first and most likely cause of black water from faucets is mineral deposits.  Water is naturally high in minerals including magnesium, manganese, and iron.  These minerals are usually colorless in water but can turn black when they are oxidized.  Mixing these minerals with oxygen at some point during the water purification process can cause it to turn black.

If oxidized minerals are the cause of your black water, then little to no safety concerns exist. Oxygen is regularly added to water supplies during disinfection and adding in more than usual doesn’t directly pose any health threats. There is little you can do to prevent minerals from oxidizing in your water because the oxygen supply added to the water is typically in the hands of your city’s water disinfection system. 

Therefore, if you believe that the cause of your black water is due to oxygen, the best thing to do is call your city and ask if their disinfection system is running properly. If black water from minerals becomes a regular occurrence, you can purchase a thorough home water filter to filter out the oxidized minerals.  A water filtration system such as a reverse osmosis filter or a water softener should do a good job to remove the minerals and prevent black water.

Black Water Caused by Outdated Pipes or Water Systems

Degradation in either your city’s or home’s piping and treatment systems can cause water to turn black.  Specifically, black water can be caused by:

  • Rusty or galvanized pipes
  • Water softener or water system degradation

First off, if your water pipes are old and not regularly inspected or cleaned, they can rust and the rust will make its way into your water.  When rust oxidizes, it turns black.  As a result, your water will turn black. A defective water softener is another likely cause of black water.  Some resin beds in softeners are colored black and when they age they can break down and cause your water to turn black. 

Also, carbon filters made out of activated charcoal can cause your water to turn black if they’re not regularly replaced.  Little particles of charcoal can run off into your water and cause it to turn black. If you think that your water is black due to pipes, then call a plumber to have them cleaned or replaced.  You’ll want to do this quickly as drinking rusty water poses potential health risks.  If you think that your water is black due to a rundown softener or water system, then you can simply replace their defective filters on your own.

Yellow Bath Water

After a long day, a warm bath can brighten just about anyone’s spirits.  However, if you turn on the bath faucet and yellow water comes out, it can be quite the mood buster.  There are a handful of probable causes for yellow water including:

  • Iron bacteria
  • Sediments in water heater
  • Rusting water systems

Yellow Water Caused by Iron Bacteria

Iron bacteria colonies are most commonly found in well water systems.  They pose little to no threat to your health but can lead to costly damage to your water system and foul-smelling water. The two best ways to prevent the formation of iron bacteria include:

  • Regular chlorination disinfection
  • Reducing water stagnation

In addition to obvious disinfectants such as chlorine, you can also prevent iron bacteria by reducing water stagnation.  Bacteria tend to thrive in still water; you can prevent still water in your well by inputting a system that keeps the water moving.  A looping water or periodic flushing system are both systems that prevent water from stagnating. If iron bacteria have already begun to form in your well, you can treat it by scrubbing out your well and then applying a chemical treatment.

Yellow Water Caused by Sediments

Through many years of use, water heaters can accumulate sediments including rust, dirt, and minerals.  The sediments will settle onto the bottom of your heater tank and cause the water to turn yellow. Sediment buildup is generally harmless and an easy fix that you can do on your own.  Simply clean out your water heater tank and the water should go back to normal.  

Yellow Water Caused by Rusty Water Systems

Just like rust in your water system can cause water to turn black, it can also cause it to turn yellow.  In this case, do the same as you would do if your water was black and have your pipes and water system checked for corrosion.

Fixing Colored Water

Colored tap water can be quite the turn-off.  To reduce the likelihood of ever having colored water or other water quality problems, regularly clean and inspect your water and water system for potential defects.  This way, you can ward off potential health issues and high-cost fixes to your water system.

Bonus tip: One of the best things you can do to help keep your water and water system colorless is to have one of the top home water filter systems!

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Joshua Perkins

Joshua spent ten years as a water systems technician in California before settling down with his wife and two young children in Nashville in 2018. Through all of his experience, he learned the benefits and shortfalls of so many different types of water filtration systems, from pitchers to whole-house installations. He started Water Filter Authority in 2019 to empower other families to make the right decision for their long-term health and wellness.