On January 14 2020, a Facebook post appeared advising readers to pour a cup of laundry detergent of fabric softener like Downy into their toilet tank, a supposed housecleaning “hack”:
Alongside a photograph of a person in yellow gloves pouring the fabric softener Downy into a toilet’s tank, the post read:
Using Laundry Detergent or softener: 🤷🏻♀️ Who Knew? 🤔 I will definitely be trying this
Pour a cup of laundry detergent in the tank of the toilet. The detergent will sink to the bottom and remain in the tank. Each time you flush, a sweet aroma will be released in the tank, and the whole bathroom will smell amazing; if you have gain fireworks as well, you can use that as well. It will slowly dissolve and will even last longer. It won’t damage your toilet or the septic system. (Credit to countrydiaries.com for the tip)
In the post, two very different housecleaning substances were suggested — laundry detergent (presumably of the liquid variety), which is used to clean clothes, and fabric softener, which is used to scent and soften clothing and linens. It wasn’t clear if the two substances would perform in the same manner when introduced to toilet tank water. In the photograph, the person shown was pouring fabric softener into the toilet tank. In just three days, more than 100,000 Facebook users shared the “tip” to their own pages or groups, spreading it rapidly.
Although the tip was presented as housecleaning advice, it didn’t actually purport to clean anything. The sole benefit of the practice supposedly involved bathroom scent, which could also be addressed through the use of scented candles, air fresheners, wax warmers, and related home fragrance products.
Another element of the claim is that it recommended either laundry detergent or fabric softener as an additive to toilet tanks. Laundry detergent is designed to be water soluble, with liquid formulas breaking down quicker than powder forms. Water temperature affects how quickly both dissolve, but even in cold water, laundry detergent wouldn’t “sink to the bottom of the tank” and continue scenting the bathroom:
Liquid laundry detergent will dissolve no matter what, although using too much of some brands might still leave blue globs or spots on your clothing. Powder detergent is designed to dissolve quickly, yet it doesn’t always do so in extremely cold water. If you wash your fabrics in the middle of a hole in a frozen lake, for instance, you may want to opt for liquid detergent. All jokes aside, unless your water is super cold, liquid and powder detergents can both perform equally well in various temperatures of water.
The advent and popularity of laundry detergent pods forced more people doing laundry to consider the mechanisms of machine washing. Many adopters of pod detergent discovered early on that in some situations, such as a large load of laundry, pods didn’t always dissolve and clothes required rewashing. Even surrounded by a harder-t0-dissolve membrane, most malfunctioning pods broke down to some degree.
In contrast, fabric softener is not designed to be water soluble in the same fashion, and it is designed to leave a residue on clothing — which is how it leaves fabrics scented. Fabric softener is also hydrophobic, in the same way that oil and water don’t mix. Advice about removing build-up of detergent and odor on clothing typically involves eschewing fabric softener despite its scent-imparting properties, for that reason:
Fabric softener doesn’t play super nicely with stretchy and moisture-wicking fabrics, as it leaves behind a coating that makes it difficult for water and detergent to fully penetrate the fibers.
Jolie Kerr of Esquire‘s popular column “Ask a Clean Person” frequently addresses the granular detail of laundry processes to readers, as most people (us included) tend to view washing machines and dishwashers as somewhat magical machines into which dirty items are inserted and clean items emerge. In actuality, detergents and additives have specific properties and behave in discrete ways, and understanding precisely how they do their jobs results in at least some level of optimized result.
While fabric softeners offer benefits, there are also some drawbacks. The emulsifiers that lend softness to clothes can also leave behind a coating that renders towels less absorbent, and that can trap odors in clothes, especially athletic gear. White vinegar can serve as a substitute for fabric softener, and has the benefit of also acting as a natural deodorizer, which makes using a half cup of it during the rinse cycle of the wash a great choice for both towels and gym gear, which tend to retains smells.
That underscores fabric softener’s best and worst traits. Most of it is highly and pleasantly scented, prompting us to want to use it whenever we can. Kerr pointed out that vinegar is a far more powerful deodorizer which both eliminates build up and doesn’t leave any, but people don’t get drawn to it the same way because it doesn’t smell like Downy.
As such, a primary issue about the “Downy in the toilet” tip was that it claimed “laundry detergent or fabric softener” should be added to a toilet tank for long-lasting clean scents. That claim was misleading, as detergent dissolves in water and fabric softener is hydrophobic, leaving a film on clothing and sometimes in washing machines or dryers.
Another objection raised by commenters involved pets like dogs who drank from toilet bowls, and claims that the practice might cause them to fall ill. If detergent or softener did leave residue in the tank, it was possible dogs might ingest some if drinking from a toilet.
As it turns out, Downy and other liquid fabric softeners were not the only laundry additives known for leaving buildup. A 2017 article on household information site HomeSteady advised readers on how to remove residue of both fabric softener and detergent from water pipes. Of note is that the article began by citing “low-temperature washing” as a cause of detergent or fabric softener build-up in pipes.
Toilet tanks are not just “low-temperature,” they are cold. Laundry is often done in warm or hot water, with some loads washed in cold or low-temperature water. Residue introduced by washers was interspersed with warm and hot water washes, whereas anything entering your pipes through the toilet is solely in cold water — likely exacerbating any problems with accumulating residue:
Low-temperature washing can cause liquid fabric softener and detergent to remain undissolved in washing machine outlet pipes. Eventually they will form a slimy substance, which may block drains, either partially or completely. Strong drain cleaner cannot be used in a washing machine and is not recommended for plastic pipes. Natural cleaners can solve the problem and are environmentally-friendly at the same time.
A separate 2017 article on the same site advises the use of fabric softener to break down adhesives and glues in wallpaper, a suggestion that points to fabric softener’s ability to loosen grip:
Several products on the market will take wallpaper borders off walls. You really don’t need them. All you need is a bottle of fabric softener, something you probably already have sitting in your laundry room. The same ingredients in this product that soften your laundry will loosen the adhesive that’s holding the borders to the walls. Once the adhesive has lost its grip, it’s easy to remove the borders.
Toilet tanks typically do not have wallpaper or borders, but they do have several plastic components, including seals and rings. Conceivably, long-term exposure to fabric softener specifically could loosen or degrade the plastic components of a toilet tank.
As for the mechanism of a flush toilet, engaging the flush mechanism typically causes the tank to almost entirely empty into the bowl. Even if the tip worked for one or two flushes, it didn’t seem likely to have a long-term effect:
A viral Facebook housekeeping hack claims that pouring a cup of laundry detergent or fabric softener like Downy in a toilet tank will scent the bathroom indefinitely, as the substances “sink to the bottom” of the tank, advice faulty for a number of reasons. First, laundry detergent is designed to dissolve in water of all temperatures, while fabric softener is designed to leave a film — the advice is inconsistent, at best. Toilet tanks empty almost entirely when toilets are flushed, so it is mechanically poor advice. Moreover, fabric softener can clog pipes over time even in washer pipes, which often carry warm water. Cold-water toilet plumbing is not designed to process fabric softener, and the substance can degrade or loosen their parts. Overall, the claim is faulty on numerous levels.