Why Your Whole House Water Filter Turns Black

by Jay | Posted on January 18th, 2023

Your water filter filters out mercury, arsenic, lead, and other harmful substances. Hence, your home’s water filter protects your family’s health.

Unfortunately, with time, your home’s water filter may turn black. This isn’t necessarily a negative thing, but it does suggest that you should change your water filter and keep your filtration system maintained at all times.

black water

Should the black particles found in my water be a cause for concern?

Although the black particles in your water have an odd appearance, they do not pose any health risks. Hence, these are not harmful. The black stuff you see could be iron or manganese flakes. These minerals won’t be harmful in any way.

However, if you find the water from your tap has an unpleasant flavor, you should report this to your water provider. You can determine if your water has excessive amounts of iron or manganese by testing it. If your water contains one of those minerals, it’s possible that your filter needs to be replaced.

Reasons that could cause your whole house water filter to turn black

The filtering medium is usually the main reason your filtering system is turning black. For instance, if you are using carbon particles, due to their small nature, they pass through the filtering system. To make matters worse, these granular particles become lodged within the cartridge, giving it a gray-black hue. The cycle continues until the cartridge filter is completely black. Here are also reasons why the water filter is turning black.


Your home’s ancient pipes or iron-rich well water may be to blame for the iron or rust in your water.

Silt and sand (black sediments)

If you use well water, you can experience issues with black sediment. This can be silt and sand. Although they are not extremely dangerous, sand and silt can lower your water quality. Sand and silt are frequently found in well water because the water travels past rocks and dirt. Over time, this could accumulate and turn your filter black.

Organic substance

Your well water may occasionally get contaminated by organic stuff that has begun to disintegrate, such as bacteria or algae. This might clog your pipes and whole-house water filter over time, turning your water murky or dark.


Manganese can be found in well water, just like iron. This is another frequent culprit of black water filters. High manganese levels may be dangerous since they may cause health issues.

Mildew or mold growth

Another reason for the water filter turning back is that it could be because your home doesn’t have enough ventilation or has excessive humidity levels, which encourage mold or mildew formation.

Activated carbon

The black hue is most likely caused by the activated carbon itself and should not be a reason for alarm when a water filter employs it. The carbon will eventually have to be changed since it will become overloaded with contaminants.

Damaged well

Your well may have sustained damage due to a strong storm or an earthquake, allowing dirt and other impurities to contaminate your water supply. Your whole-house water filter may become clogged by this and turn black.

Septic system malfunction

Your water filter may potentially turn black if your septic system malfunctions. Sewage leaking from the septic tank can enter the groundwater, which is then filtered by your whole-house water filter.

Corrosion in the water pipe

Ask a plumber to come out and look at all of the pipes in your house. Your home could sustain significant damage from a corroded plumbing system or fail suddenly in the spring.

You need to check for corrosion because iron is mostly used to create water pipes. Over time, the iron particles rust and produce corrosion all around the surface. These iron particles are transferred to your filtration by the current when water flows past the corrosion area, pushing up gobs of black gunk.

How to identify the reason why your whole house filter is turning black

Water crown splash. On black background. Side view.

Here are some steps you can take to identify the reason for your whole house filter turning black.

Test your water

Test your water to determine the cause as a good starting step. There are various water test methods, but you should check for manganese and iron. You have two options to do this. You can get a kit for do-it-yourself testing from a hardware shop or hire a pro to do the testing for you.

Check for buildup or leaks

Inspect your carbon filter to see if it has built up too much grime or is leaking. Sometimes, you need to update your whole house’s carbon filter.

Check the health of your septic system

To ensure that your septic system is operating properly, you should have a professional inspect it at least once a year. It is because your entire house water filter will turn black due to impurities released in your water system by a failing septic system.

Inspect your well’s water level

Inspect your well to see whether the water level has dropped. If the water is low, this could mean that your well is drying up and sediments are making their way into your water supply.

Look for signs of corrosion

Pipes typically made of iron are susceptible to rust and corrosion. Look for corrosion in your water heater and pipes. Ensure that they are checked and fixed as necessary.


A water filter in your house is crucial for health and hygiene reasons. This ensures that hazardous pollutants are removed, providing safe and potable water. Sadly, most water filters eventually become clogged and black. If you do not know what causes your water filter to turn black, you can test for any of the possible reasons we mentioned above.


Jay is a health and wellness enthusiast with expertise in water quality and nutrition. As a knowledgeable advocate for holistic well-being, Jay successfully manages Type 2 Diabetes through informed lifestyle choices. Committed to sharing reliable and authoritative insights, Jay combines firsthand experience with a passion for enhancing health."