Why Is My Toilet Tank Water Dirty? |BROWN|

Toilet Tank

Dirty toilet tank water is an infrequent occurrence. However, when it occurs, it is quite upsetting. Usually, the tank is closed from the top, due to which you cannot peep inside effortlessly. It is only when you open the tank to see how the water or tank condition is.

It is wise to lift the lid from time to time, as you may be stunned by the visuals inside. One of the common visuals you tend to come across is the water discoloration, which does not necessarily get transmitted at the time of flushing.

However, seeing such water through the bowl is the only way to know about this water issue if you do not open the tank frequently to check its internal health. Seeing that alarming orangish or brownish water can put you on high alert.

However, there is no need to be on such an alert, as this nasty water is just not unsafe or harmful. It is just an indicator that you have a normal pipe issue. Fortunately, this issue is resolvable by a plumber. At times, discolored water from the toilet tank may be a sign of a plumbing emergency.

What Discolors the Water in the Toilet Tank?

Discolored water in the toilet tank could be an indicator of clogged sewer pipes. If you fail to discard the clogs soon, the plumbing pipes are then at a higher risk of bursting or cracking than before due to the clogs-induced pressure inside.

Moreover, the hard water minerals are likely to form the clogs or blockages to accumulate inside the tank. The usual sources of filth in the toilet tank are water minerals, algae, mold, metal parts inside the tank, and pipe corrosion itself.

At times, the water supply itself is contaminated due to well issues or some work being carried out at the local water purification system. In this case, even the faucets will tend to show discoloration.

The color of the tank water is likely to differ from reddish to brown, depending on the kind of mineral accumulation. For instance, the presence of calcium and magnesium converts the natural watercolor into brown upon mixing with the tank’s oxygen.

On the other hand, manganese turns the appearance of water into dark black when exposed to air. Further, minerals such as iron are likely to darken the water by generating rust on the metal fixtures and internal tank parts, splitting and floating in the water, and sticking to the tank’s bottom to form a thick coat.

These minerals most likely harden inside are difficult to remove. Generally, iron in the water is the most common culprit behind brown discoloration. This water indicates that there is rust on the old galvanized pipes or the water supply is full of iron compounds.

Iron, by itself, is not an issue, as it is not harmful or toxic. However, it is an issue when it stains the internal sides of the tank. This not only discolors the water but also promotes bacterial growth. Even though, do not panic if you find yourself drinking tap water rich with iron.

This is because the discoloration you see is only rust, which is analogous to what you observe on a bike or bicycle left outside for too long in the rain.

Although it sounds unpleasant, it is just not necessarily harmful. Nevertheless, it gives rise to serious issues such as less water flow due to its deposit or leaky pipes as its metal is significantly destroyed due to too much rust.

In case the water source is a well, the tank water’s brown color is likely due to the dissolved organic content. Usually, the residue accompanies this discoloration. No matter which of the two is present, it could mean that you need to pay attention to it. It may have been so that landscaping works or storms might have breached the well.

How Hard Water Minerals Become a Part of Water Supply?

Hard water minerals such as iron, magnesium, calcium, and manganese typically come from the chemicals or cleansers you rely upon for cleaning your toilet, sink, and tubs. However, several chemicals of toilet cleaners do not drain down the toilet bowl fully when you flush it.

A few chemical gels cleansers tend to form a firm layer on the toilet bowl’s surface for many days. These chemicals only leave fully when you flush several times and reach the sewer line attached to the base of your toilet.

When these chemicals accumulate in large quantities inside the sewer line, they result in hard blockages or clogs. These blocked sewer lines are likely to push back the wastewater up to the plumbing pipes of your bathroom.

This is where the wastewater mixes with the plumping pipes’ clean water. The assorted water then goes across the plumbing system of your toilet and finally reaches the tank. When it comes inside the tank, the minerals are pulled from the water, which then sticks to the tank’s surface.

What about the Mold in the Tank?

As a toilet tank remains closed, it is an ideal breeding ground for mold and algae. The presence of these microorganisms is likely to make the water cloudy or green. Further, a few types of bacteria also grow in these tanks, especially if the water has a significant number of iron compounds. These organisms are typically white or pink.

What You Can Do?

It is simple! You can discard any type of algae, mold, or bacteria by thoroughly cleaning the tank. You start by emptying the tank with the gloves-covered hands and wash the tank’s sides along with all internal parts using a disinfecting cleaner.

Finally, rinse the tank, allow it to dry, and then fill it water. To this water, just add a cup or more of vinegar and allow the mix to settle overnight before you flush.

If after this treatment the water appears discolored, it is time to check the other water sources in your house, including the pipes. This is where you will need a plumber.


The water in a toilet tank can be dirty due to mold, algae, and hard water mineral deposits. To avoid it, consider cleaning the tank frequently with vinegar. 

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