Ask the Builder: Cleaning the inside of a toilet tank

Ed subscribes to my free weekly newsletter. He lives in western North Carolina, as does his son. His son’s house was flooded by a portion of the trillions of gallons of water Hurricane Helene unleashed on the interior Southeastern USA.

Ed’s son thought he was doing the right thing by asking one of the artificial intelligence (AI) engines the best way to clean and sanitize the inside of his toilet tank. Ed sent me the computer-generated answer, and it made me grimace.

The best analogy I can offer is the following instructions on how to bake a cake: Turn on your oven. Mix some flour with sugar and a few eggs. Stir these up and pour into a pan or two. Bake until a toothpick doesn’t have batter on it when you pierce the center of one of the pans. Remove from the oven, let cool, and slather on some icing.

If you’re a pastry chef or know a thing or two about baking cakes from scratch, my step-by-step instructions above would lead to a culinary disaster. So too the AI instructions about cleaning and sanitizing the inside of a toilet tank.

Ed’s son was most interested in sanitizing the toilet tank. Flood water is almost always polluted. The AI instructions said to use vinegar to sanitize the tank. The U.S. Environmental Protection Agency doesn’t recognize vinegar as a household disinfectant. Chlorine bleach is a powerful sanitizer and disinfectant. The chlorine ions can achieve a 99 percent bacteria kill in less than 60 seconds if you use the right solution.

The parts inside a standard toilet tank make it difficult to clean. The fill valve, overflow tube, flapper valve and flushing handle can get in the way of your cleaning efforts. My recommendation is to remove and discard the fill valve and flapper valve as part of this cleaning and sanitizing project. Both are very easy to replace.

Before you take everything apart, the first thing to do is to fill several five-gallon buckets with clean water. Do this if you only have one toilet in the house. You can use this water to flush the toilet should you have to use it as you work on the tank. If you only have one bucket, you can refill it with water from your tub spigot, shower head or garden hose.

I’ve cleaned and sanitized my own toilet tanks in the past without removing the parts. I turn off the water supply to the tank and then flush the toilet holding down on the handle. This keeps the flapper valve up and gets most of the water out of the tank. Let go of the handle once the water has drained from the tank.

I then fill up a bucket with very hot water. I fill the toilet tank up to the top of the overflow tube in the center of the tank. The next step is to add two cups of powdered oxygen bleach to the water in the tank. It should immediately begin to bubble. The oxygen ions are starting to clean the tank and all the parts without your help.

High-quality oxygen bleach is also a great sanitizer. It’s not on the official EPA list because it can’t get the 99% bacterial kill as fast as the standard requires. That said, if you let the oxygen ions bubble in the tank for 45 minutes, you’ll get the desired 99% kill rate.

You can flush the toilet after an hour. The tank will fill with clean water. You may want to flush it a second time. The inside of the tank may be stained from years of bacteria growth, iron stains, etc.

To get the inside tank surface as clean as the day it was installed, it’s best to remove the fill valve, the flapper valve, and the flushing handle arm. It’s very simple to do this. There are many online videos showing you how this is accomplished.

The cleaning process is now easy because you can get your hands and different brushes into the tank with minimal interference. Liquid dish soap should do a great job at getting most of the stains off the china.

Iron staining can be cleaned by spritzing the inside of the tank with an oxalic acid solution. Oxalic acid is a dry powder you can purchase online. You can also fill the tank with water and add the powder.

Install the new flapper valve, making sure the valve seat that’s part of the overflow tube is clean. With the flapper valve in place, you can fill the tank again with clear cold water. Add a cup of oxalic acid powder, stir it up, and let it sit for hours. You’ll be stunned at how the rust stains disappear with no scrubbing.

Neutralize the oxalic acid with baking soda before you flush the toilet. You don’t want an acid solution harming your septic system or creating havoc in your city sewer system.

When working with any chemicals, stop and read all the safety instructions that come with the product. Wear goggles and gloves, be sure the room is well ventilated, and by all means don’t mix two chemicals together!

You’ll undoubtedly have to scrub the inside of the tank to get the best results. It’s no different from taking a shower. Your hands rubbing your skin are the primary reason you get clean. Cleaning requires mechanical agitation for the best results.

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