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

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


Do you have limescale in your toilet bowl?

Wait, what is limescale? It’s a hardened build up of minerals that starts with a greyish cast and can turn an unsightly brown colour when rust develops on the outer layer.

I’d never dealt with toilet limescale before moving to Sydney. Our toilet developed this 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 would surely bother our rental agent when we eventually moved out, but furthermore, a brownish mark on the bottom of a toilet bowl looks unclean, no matter what the reason. Which is why I took a dramatic before picture, but ultimately decided against posting it.

But you know what bothers me more? Household chemical arsenals that could be mistaken for m#th labs. I resent the ease with which we can buy harsh chemicals when a few simple and inexpensive ingredients can do a fine job.

My approach to household cleaning

I strive for cleanliness, rather than sterility, the latter of which is a fool’s errand – nature hates a vacuum. I don’t buy commercially made surface cleaners, window cleaners, or toilet cleaners. Instead I use white vinegar, bi-carb (baking soda), castile soap, sea salt, and occasionally hydrogen peroxide. All are inexpensive and don’t irritate my respiratory tract. I refill everything but the hydrogen peroxide locally and, if motivated to, I could make vinegar, salt, and maybe even the castile soap myself.

These ingredients are fine for the outside of the bowl, but I struggled to figure out how to clean the hard scale on the bottom of the toilet bowl. Scrubbing harder wasn’t helping.

While searching some forums for tips, I came across a lot of dubious advice about how to remove the stains – use hydrochloric acid / WD40 / Coca Cola, use a chisel / screwdriver / sandpaper, replace the toilet, or my personal favourite bad idea: use a power washer….indoors. Our perception of the scale of the challenge frames the level of response we think it deserves. Looks like concrete? Try a jackhammer! Who knows, maybe these methods all work, but call me low-tech, it was this one infrequently mentioned solution caught my attention: citric acid.

What is citric acid?

Citric acid is found in citrus fruits, highest in lemons. It’s used in the kitchen for jam, tofu and cheese making, food dehydration, and more. It’s what makes citrus taste sour.

I was intrigued because it sounds gentler than chlorine bleach, and if the citric acid didn’t work on the toilet, 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 experimented by adding a tablespoon to the bowl and left it for about an hour. The size of the stain reduced, but it wasn’t the overall miracle I was after. For the next attempt, I upped the dose to 35 grams of citric acid (about a third of a cup, eyeballed) and let it sit overnight.

In the morning, I saw 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).

Zero waste toilet bowl cleaner

I should mention that in drought-prone Australia, low flow toilets are the norm and there is only a small amount of water in the bowl (as seen in the pic) compared to North American toilets.

Would lemon juice work instead of citric acid?

Yes, probably, but you’d need lots of lemon juice to get the equivalent amount of citric acid. An ounce of lemon juice only has about 1.5 grams of citric acid, and this will vary from fruit to fruit. If you live where lemons are abundant, go for it. 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 used kombucha vinegar to clean the toilet, I’d be curious to hear about your experience.

Is this really a Zero Waste solution?

I didn’t buy the citric acid in bulk or unpackaged, but that’s less of concern to me because a Zero Waste approach is more than a question of packaging, it’s an overall less is more approach.

  • The crystals are sold in crystallised form, which means less cost to ship around, and less plastic packaging to move the weight of liquid.
  • 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.

A word of caution on DIY and ‘natural’ cleaners

I subscribe to the idea that we should reduce the volume and breadth of industrial chemicals we produce and use everyday. However, please keep in mind……

Natural isn’t chemical free or non-toxic

‘Natural’ cleaners are still made of chemicals. The widespread use of the term chemical-free bothers me because it’s scientifically inaccurate and reinforces the pervasive and damaging belief that natural is always better, and never harmful. That belief is harmful. 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. Useful stuff.

Some cleaners don’t play well together

The normal rules of chemical reactions apply to DIY cleaners. 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. I would suggest labelling your cleaners with what is in the bottle what it shouldn’t be mixed with. You may know what’s in there, but your children, roommates, or partner may not.

Citric acid cleans toilets easily and cheaply

I felt over-the-top clever learning and applying this little hack and am excited to share it with you. Simple and inexpensive solutions are best, because Zero Waste should be accessible for everyone. Have you ever used citric acid for cleaning? I’d love to hear about it.

6 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 🙂

    1. Hi Meg, not sure. Is there a rubber gasket seal inside the cistern? I suspect that any commercial cleaners are at least as acidic (in fact, you might even find citric acid as an ingredient on toilet bowl cleaners), so I haven’t been concerned.

  2. THANK YOU THANK YOU THANK YOU for this!!!!!
    I have spent hours and hours scrubbing with a pumice stone over the last few years to only ever get a small amount off. We have been so close to replacing the toilet but the cost of doing it in a heated tiled bathroom had deterred us slightly!
    I was so skeptical but it WORKED!!!!
    Oh my goodness I just can’t thank you enough!

Leave a Reply

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.