Table of Contents:
Question: How do you remove black stains from inside of the toilet tank? The water is clear and the bowl stays clean.
Over 
time, minerals in the water can leave a build-up inside of the toilet tank. Though often these are not harmful, they can be annoying when trying to clean. A simple acid-based cleaner will quickly remove any mineral deposits and leave the tank looking clean and fresh.
You Will Need:
- Vinegar
- Coca Cola
- Bar Keepers Friend Powder
- Soft Scrub with Bleach
- Scrub Free
- Scrubbing sponge or toilet brush
Steps to Clean the Tank:
- Begin by turning off the water and flushing the toilet to drain the tank completely.
- Next, fill the tank with vinegar or Coca Cola. The acid in either of these will loosen the mineral deposits and make them easier to remove.
- After allowing it to set overnight, flush it away.
- Use the scrubbing sponge to scrub the sides of the tank to remove any remaining stains.
- Repeat as necessary.
- A second method involves applying a series of cleaners. If the stain is removed early in the process, there is no need to continue with the remaining cleaners.
- Start by turning off the water and flushing to empty the tank.
- Use the scrubbing sponge to apply a layer of Soft Scrub. Allow it to soak and then scrub.
- Rinse away with water and flushing.
- Next, apply a layer of Scrub Free. Again, allow it to soak and then scrub the stain.
- Rinse away with water and flush it away.
- Last, apply the Bar Keepers Friend Powder and scrub with the sponge.
- Allow it to set on the stain and then rinse and flush away.
- Repeat any of the above steps if necessary until the stain is completely removed.
Additional Tips and Ideas
- If you have a private septic tank, avoid using too many bacteria-killing cleaners (such as bleach). These septic systems require bacteria to effectively destroy the waste. Instead, use cleaners such as Rid-X that keep the needed bacteria in the system.
- If rust is a problem, there are rust removers available at nearly every store that sells toilet bowl cleaners.
- If there is a built-in shelf or other item that prevents you from scrubbing the tank, drop in a few denture tablets. The fizzing will scrub off most stains.
- If the toilet is vitreous china, you can scrub the stains away with a pumice stone. Do not use these stones on colored, enamel or plastic toilets.
- It is recommended that you clean the inside of the toilet tank twice a year.
Fill the WHOLE cistern with vinegar? (That would be a LOT of vinegar.) Would pouring some on the bottom, and srubbing some into the walls be OK?
Amen to Merc’s comment (2011) about all that vinegar! What was the answer? My tank is old and horribly discolored (the lid has weird orange stains that won’t come off even with an SS scrubber). The tank has dark patches, including a blue line from a blue sticky “pod” someone put in a long time ago. The blue line is above the current water line. HELP!
The toilet tank can hold about 5 gallons. Vinegar is sold by the gallon at most stores (as well as in smaller quantities).
You can place a milk jug or even an empty vinegar jug in the tank to take up space and use less vinegar or soda. Clean the label from the bottle, fill the jug with water and place the jug in the tank.
Another idea: you could try using the vinegar as a poultice. Cut a brown paper bag into strips, soak the strips with vinegar, place the strips against the walls of the tank and wrap a layer of plastic wrap over each wall of the tank.
Source: Savvy Practicality – Is Your Toilet Efficient?
Source: wikiHow – How to Convert Any Toilet to a Low Flush Toilet
Source: Hella Delicious – Vinegar and Brown Paper Poultice