How to clean tough toilet stains (the zero waste way)

Here is a beautifully straightforward Zero Waste method to descale your toilet bowl easily and inexpensively without using bleach, a chisel, or a power washer indoors. 

Raise your hand if you have limescale

Wait, what is limescale? I’d never had to deal with it before I moved to Sydney. It’s usually caused by the minerals in hard water, so it’s a bit of a mystery, as Sydney has soft water. Perhaps not as soft as Vancouver.

Anyway, our toilet rather unfortunately developed a cement-like stain in the bottom of the bowl and at the water line, over a period of about a year, in spite of regular cleanings. It starts with a greyish cast, but can turn an unsightly brown colour if rust also develops. I don’t have to tell you, a brownish mark on the bottom of a toilet bowl looks gross and unclean, even if it’s just mineral buildup from the water itself. Which is why I took a dramatic before picture, but ultimately decided against posting it. It was bothering me, and would no doubt bother our rental agent upon our eventual departure.

But you know what bothers me more? Household chemical arsenals that could rival a m#th lab. I resent the ease with which we can buy this stuff when a few, simple and inexpensive, ingredients can do a fine job.

My permaculture-ish approach to household cleaning

I strive for cleanliness, rather than sterility, the latter of which is a fool’s errand – nature hates a vacuum. It should surprise no one to hear that I don’t buy commercially made all purpose cleaners, window cleaners, or toilet cleaners. What I do buy is vinegar, bi-carb (baking soda), castile soap, sea salt, and hydrogen peroxide. I can refill all but the hydrogen peroxide locally. If motivated, I could make vinegar, salt, and maybe even the castile soap myself.  Bonus points for all these being super inexpensive.

Now these are all fine for the outside of the bowl, but I struggled to figure out how to clean this hard calcification on the bottom of the toilet bowl. Elbow grease wasn’t doing it. While searching some forums for descaling tips, I saw a lot of dubious advice – use hydrochloric acid/WD40/coca cola, use a chisel / screwdriver / sandpaper, replace the toilet, or my personate favourite, use a power washer….indoors. It seems our perception of the scale of the challenge of the task really frames the level of response we think it deserves. Looks like concrete? Try a jackhammer! Who knows, they probably all work, but there was this one infrequently mentioned ingredient that caught my attention: citric acid.

What is citric acid?

You might recognize the name from the kitchen context, where it’s used in jam, tofu and cheese making, food dehydration, and more. Citric acid is found in citrus fruits, highest in lemons. It’s what makes citrus taste sour. If you dehydrated lemon juice, you’d be making citric acid crystals. I was intrigued because on the whole it sounds gentler at least than chlorine bleach or an acid we donned safety goggles for in high school science lab. At least if the citric acid didn’t work, I could use it in the kitchen.

citric acid from lemon

The test: can citric acid clean my toilet?

I bought a small amount of citric acid crystals from the supermarket to test. I first experimented with a tablespoonful and left it for about an hour. This seemed to work at the edges only – the size of the patch reduced. It held promise but it wasn’t the overall miracle I was after. So next I added 35 grams (about a third of a cup, eyeballed) to the toilet bowl and let it sit overnight. The crystals sunk to the bottom to do their work.

In the morning, there were some greyish patches of debris floating on the water’s surface. A flush revealed the miraculous result: ceramic perfection. It worked! All the cement-like rock solid crud was completely gone, dissolved. And there was no scrubbing, chiseling, or power washing required. All this for a total cost of $1.40 (AUD).

I should mention that in drought-prone Australia, toilets are mostly low-flow, meaning there is only a small amount of water in the bowl (as seen in the pic) as compared to in North America (and the flush action still works fine, if not better). For the latter, a full bowl might be better partially emptied, or the amount of citric acid increased. Next time I will try using less and let it stand for a longer period. However, now that I know the secret, I’ll probably use a dabs here and there to prevent the issue in the first place.

Would lemon juice work instead of citric acid?

Yes, but you’d need lots of it to get the equivalent amount of citric acid. An ounce of lemon juice only has about 1.5 grams of citric acid, but of course this will vary from fruit to fruit. If you live where lemons are abundant, go for it, and also consider that as a general rule later in the season the lower the acid level, meaning you’d need more of them. I could probably only buy two or three lemons for the same price, so citric acid is more cost effective.

Ultimately citric acid is not the only solution. The trick is using an acid on the limescale, so probably vinegar would work too. If you make kombucha, you can easily make vinegar. If you’ve done so and used this to clean the toilet, I’d be curious to hear about it.

Is this really a Zero Waste solution?

I want to clarify that I didn’t actually buy the citric acid in bulk or unpackaged. However, I’d still consider this part of a Zero Waste approach, because…Zero Waste is an approach.

  • Compared to the commercially sold limescale removal alternatives (CLR for example), I significantly reduced the plastic in the packaging, and, in fact, the volume of packaging.
  • I needed to use only a small amount to work.
  • I didn’t need to buy rubber gloves or a face mask to protect myself from chemical burns or respiratory damage.
  • If I needed to, I could actually make this substance myself, which fits in with a permaculture approach.

Since I have a bit leftover, I’m also interested to experiment with a citric acid solution as a shower glass cleaner. The water marks on the glass are likely caused by the same mineral buildup, and while my bi carb scrub followed by vinegar spray works okay, what if I didn’t have to scrub? Have I mentioned I’m lazy?

A word of caution on DIY and ‘natural’ cleaners

I subscribe to the idea that we should, as a society, reduce the volume and breadth of industrial chemicals we produce when we’re really not all that clear on their interactive and cumulative effects in the ecosystem. However, please keep in mind……

Natural isn’t always better

The widespread use of the term ‘chemical-free’ and irks me, not only because it’s scientifically inaccurate, but because it also suggests no harm, and reinforces the pervasive and damaging belief that natural is always better, and never harmful. That belief is harmful. ‘Natural’ cleaners are still made of chemicals. Essential oils can be toxic, asbestos is a natural substance, etc. Chemicals are not by definition harmful and natural is not by definition safe. Science is not a religion, it’s just controlled testing, and believe it or not, some science people are testing things like the impact of vinegar on microbes. Good people. Useful stuff.

Some cleaners don’t play well together

Given that we’re still using chemicals when we DIY, it means the normal rules of chemical reactions apply. I don’t own bleach, but if you do, keep in mind that you should never, ever mix acids with bleach. Citric acid and vinegar are both acids. If there are any chemists stopping by, feel free to comment below if there are any other bad combos I should add. I would definitely suggest labelling your concoctions at the very least with what it is and what it shouldn’t be mixed with. You may know what’s in their, but your children, roommates, or partner may not.

Citric acid cleans toilets easily and cheaply

I really felt clever learning this little hack and am excited to share it with you. I love it when a solution is simple and inexpensive, because Zero Waste should be accessible for everyone. Have you ever used citric acid for cleaning? I’d love to hear about it.

2 thoughts on “How to clean tough toilet stains (the zero waste way)

  1. I laughed out loud when I read your comment “…use hydrochloric acid/WD40/coca cola, use a chisel / screwdriver / sandpaper, replace the toilet, or my personal favourite, use a ***power washer***….indoors. ”
    Because I actually tried using my UK imported Karcher K4 Power Washer full blast and it did NOTHING… except I got soaking wet covered in splashes from the …toilet…. lovely it was!
    Fortunately I live in Singapore where the bathroom is fully enclosed, fully tiled and right next to the shower… after I gave up, needless to say the next thing I did was to have a hot shower!
    I have yet to try an acidic chemical floor cleaning fluid I have (for fear it may damage the enamel… For a couple of dollars spent on Citric Acid – its got to be worth a try!
    Thank you for making me laugh – have a great day 🙂

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