Red Residue From Water (6 Possible Causes & How To Resolve)

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Noticing a red residue from your water? You’re right to be concerned – but thankfully, pink or red stains can usually be resolved easily.

In this guide, we’ve shared the 6 most likely causes of red residue from water, and the easiest ways to resolve these issues.

๐Ÿ“Œ Key Takeaways:

  • Red or pink water residue may be caused by iron, serratia marcescens bacteria, iron bacteria, potassium permanganate, sediments, or rusty pipes and water heaters.
  • You can address red residue in water by removing contaminants or preventing contamination that leads to red discoloration.
  • Vinegar and water make a great natural cleaner for red residue on bathroom and kitchen surfaces.

๐Ÿ”Ž 6 Causes Of Red Residue From Water

Here are the common reasons why you’ll notice red or pink residue from your water:

1) Iron

Iron is a mineral that occurs naturally in many groundwater supplies. It’s the fourth most abundant element in the world, so if you have a private well, there’s a good chance that it contains iron.

Depending on the type of iron in your water, it may turn your water a reddish-orange color, or it may be completely dissolved in your water, so you’re unaware of its iron content from appearance alone.

Insoluble ferric iron is the type of iron that you can see in water. Ferrous iron is invisible, but it may turn a rusty brown or yellow color after water is left standing.

Iron stains surfaces when it’s exposed to oxygen. You may notice reddish-orange or brown stains in your toilet bowls, sinks, bathtubs, shower stalls, any other bathroom surfaces that come into contact with water, and even in your pet’s water bowl.

If your water contains iron, you’ll likely also notice a metallic taste and smell. While iron isn’t harmful to health in the low concentrations found in well water, it does cause aesthetic damage to your plumbing fixtures.

Red water stains due to iron contamination

โœ… How To Resolve

The best way to resolve red or orange stains caused by iron is to install a water treatment system that can target this mineral.

First, test your water to see if it contains ferric iron, ferrous iron, or both. The type of iron your water contains will determine the most suitable form of treatment.

If your water contains low levels of soluble ferrous iron, consider installing a water softener. Water softeners remove calcium, magnesium, and low levels of ferrous iron, exchanging these minerals with sodium or potassium chloride ions. These systems prevent hard water scale, soap scum, and ferrous iron staining, but they can only be used to remove low levels of ferrous iron (around 1-2 PPM).

If your water contains ferric iron or a combination of both types of iron, install a dedicated iron filter, like an oxidation system. This system sends water through an oxygen bubble, which oxidizes any dissolved iron, manganese, and hydrogen sulfide. These oxidized contaminants are then filtered out of the water, typically with birm or manganese greensand media.

Water oxidation system, control app and sediment filter

2) Serratia Bacteria

Serratia bacteria is another possible cause of red or pinkish water. These bacteria occur naturally in soil, animals, and foods, and produce a characteristic red pigment in water. They thrive in environments with dust, moisture, fatty substances, and phosphates, and are very hardy, requiring very little to survive.

You may find that the pinkish film appears in your water when you’re renovating or constructing part of your home. The airborne bacteria in the dust and dirt produced by building work will eventually seek out moisture, which means it may end up in your drinking water.

Serratia marcescens was first thought to be a harmless bacteria, but recent research has found that these bacteria may have pathogenic effects in some people, especially those with weakened immune systems. In hospital environments, this bacteria has been identified as the cause of wound infections, urinary tract infections (UTIs), and pneumonia.

โœ… How To Resolve

The best way to avoid serratia marcescens bacteria in your water is to prevent moist or dusty conditions in your home.

First, check that the cause of the pink stains is serratia. The mysterious pink rings in your porcelain sinks, tile grout, shower curtain, and bathtub enclosures could also be caused by other contaminants, so test your water for serratia to double-check.

You should then work on reducing moisture and making it more difficult for serratia to grow in your bathroom. There are a few ways to do this:

  • Clean your bathroom frequently with a good bathroom cleaning solution. Pay particular attention to areas where you’ve noticed the bacteria growing, such as your shower stall or shower curtain, and your bathroom tiles.
  • Install an exhaust fan. If you don’t already have a bathroom exhaust fan, install one as soon as possible. Switch the fan on whenever you’re bathing or showering, and it’ll suck moisture out of the room to prevent bacterial growth. You can also open windows wide to achieve a similar effect.
  • Avoid stagnant water. Make sure there’s no standing water in your bathroom. Empty sinks and bathtubs as soon as you’ve finished using the water.
  • Keep renovation work localized. If you’re renovating a part of your home, close it off from the rest of the property to prevent the spread of airborne bacteria.
  • Be wary of using activated carbon filters. If you use an activated carbon filter to remove chlorine residual from a city water supply, serratia marcescens are more likely to grow. It’s best to use activated carbon filters at a point of use location (i.e. once water leaves your kitchen sink), rather than using a point of entry filter.
Removing pink stains cause by serratia bacteria in shower tiles

3) Iron Bacteria

Iron bacteria is another possible cause of reddish or pink slime in your toilet bowl, toilet tank, and other fixtures and other water-using appliances.

Iron bacteria are microorganisms that occur naturally in soils and groundwater supplies. When groundwater flows through soils containing these bacteria, they contaminate the water supply, resulting in iron deposits and slime.

Iron bacteria aren’t typically harmful to health. However, they do have damaging aesthetic effects and may clog your shower heads, drains, and faucet aerators.

โœ… How To Resolve

Iron bacteria may simply be naturally present in your tap water, but there are several reasons that may increase the likelihood of iron bacteria contamination, including poor well construction, a lack of well maintenance, or work carried out on a well with contaminated equipment.

So, you can often prevent iron bacteria by properly maintaining your well and repairing cracked casing or damaged seals, and making sure that any tools or equipment used are clean and bacteria-free.

๐Ÿ‘จโ€๐Ÿ”ง To thoroughly remove iron bacteria from your well, we recommend shock chlorinating your well with a strong chlorine bleach solution. Here’s our guide on how to shock a well.

You can also install a whole home water treatment system that will remove iron bacteria and improve your water quality. A chlorine injection system is the best solution. Measured amounts of chlorine bleach are injected into the water, which kills microorganisms, including iron bacteria.

Adding chlorine to chemical injection pump

4) Treatment With Potassium Permanganate

If you use a chemical injection system or a filtration system that treats water with potassium permanganate, there’s a small chance that your water’s pinkish tinge is caused by this chemical.

Potassium permanganate is an oxidant that’s used to remove iron, manganese, and hydrogen sulfide from water. It turns water slightly pink, even at low doses.

โœ… How To Resolve

If your tap water has only a pink tinge, you probably don’t need to worry about the effects of potassium permanganate. Your water shouldn’t leave pink stains, and low levels of potassium permanganate are safe to drink.

However, it’s worth checking your user manual or contacting the manufacturer of your water treatment system if you’re unsure. Sometimes, noticeably pink water is a sign that you’re using too much potassium permanganate, which could have health effects in the long term.

5) Certain Sediments

Certain sands, silts, and other sediments could also cause your water to take on a reddish-brown color or leave red, orange, or pink residue on your surfaces.

Sediment is another common contaminant in well water. You’re especially likely to have sediment in your water if your well is drying up or your well pump is positioned too close to the bottom of the aquifer, causing it to draw sand and silt a well as water.

โœ… How To Resolve

First, check that sediment is the cause of your water’s red residue. Fill a glass with water from your tap, then wait five minutes. If a layer of sediment has settled at the bottom of the glass, and the water at the top looks clearer, sediment is the problem.

You can remove sediment from your water with a whole-home sediment filter. Sediment filters can trap sediments as large as 100 microns – sometimes even larger – all the way down to 1 micron or less. Spin-down sediment filters are best suited to remove large particulates, while cartridge sediment filters are best for smaller particulates.

Sediment filter next to a water tank

6) Rusty Pipes

Finally, rusty pipes or water-using appliances might be the reason why your water produces a red residue.

Rust can accumulate in old, corroding pipes and water heaters, and flowing water causes rust particles to break off and enter the water supply.

If your pipes or water heater are rusty, you’ll notice that your water has a red residue, and you might also notice flakes of rust in your water.

Other signs of rusty pipes include:

  • A metallic or earthy odor
  • Stains on laundry, sinks, bathtubs, and other fixtures
  • Reduced water pressure due to the accumulation of rust particles

You might also notice signs of corrosion on the outside of your pipes, although your pipes may be corroding internally with no sign of external damage.

โœ… How To Resolve

You can resolve a rusty pipes or water heater issue by hiring a professional to inspect your plumbing system and advise you on the next steps.

Sections of your plumbing may need to be replaced, or it might be time for a new hot water heater.

You could also install a sediment filter to remove the flecks of rust from your water, but this won’t prevent your plumbing system from continuing to corrode, and you will likely need to address the root cause of the issue.

Checking main water pipe in home

๐Ÿงผ How To Clean Red Water Stains

So, now you know how to identify and prevent red residue, but what can you do if you already have red, orange, or pink stains on your appliances?

Our top cleaning advice for removing red or pink residue from surfaces is to use one-part vinegar and one-part water. You can use lemon juice in place of vinegar if that’s more convenient.

Add the solutions to a spray bottle, shake, and spray onto your surfaces. Use a sponge or a soft-bristle brush to scrub off the stains. Be careful not to scrub too hard, as bacteria may accumulate on gouged surfaces.

For more stubborn stains, combine equal parts white vinegar and baking soda to form a paste. Apply the paste on the stain, then let it sit for up to 30 minutes before scrubbing with a sponge and rinsing with clean water.

๐Ÿ”š Final Word

Red water stains are unpleasant to look at, but thankfully, they’re usually easy enough to deal with.

If you don’t know what’s causing your water stains, start by testing your water for the most likely contaminants. A good testing laboratory should be able to advise you on what to test for based on the appearance and color of the residue you’ve noticed.

Once you know the cause of the red or pink residue in your water, you can address the issue with the most effective water treatment solution.

  • Jennifer Byrd
    Water Treatment Specialist

    For 20+ years, Jennifer has championed clean water. From navigating operations to leading sales, she's tackled diverse industry challenges. Now, at Redbird Water, she crafts personalized solutions for homes, businesses, and factories. A past Chamber President and industry advocate, Jennifer leverages her expertise in cutting-edge filtration and custom design to transform water concerns into crystal-clear solutions.

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