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I drew on my background as a chemical engineer to offer insight into the effectiveness of these controversial chemicals. In my experiment, I tested eight of the most commonly available chemical drain cleaners: six alkaline and two acidic. I performed dissolution tests to evaluate how well each of them could dissolve drain blockages. I had one goal: determine which products, if any, would work effectively against the most common clogging materials.
For this roundup, I headed to CNET’s product testing lab in Louisville, Kentucky, to conduct a comprehensive batch distillation experiment with eight of the most widely used chemical drain cleaners on the market. My primary goal was to determine each product’s efficiency at dissolving various types of clogging materials, including organic matter, grease, paper products, and pet hair (the same pet hair we used for our tests of robot vacuum, in fact). Throughout the experiment, I also noted the pH levels of the cleaning solutions when mixed with water and monitored any temperature changes. Additionally, I considered the chemical composition and versatility of use of each product when comparing them to each other.
Acids vs. bases
Before conducting experiments with these substances, I separated them into acids and bases. As you may remember from high school chemistry, acids are compounds that donate a hydrogen ion (H+) when mixed with water and have a pH less than 7. On the other hand, bases are compounds that accept those ions (or hydroxide, oh- ions) and have a pH greater than 7. Understanding this distinction is crucial, due to two important factors associated with these products: corrosivity and causticity.
Corrosivity refers to a chemical’s potential to cause rust and deterioration of the materials that make up your plumbing system. Causticity, on the other hand, relates to how a chemical reacts when it comes into contact with organic matter, specifically breaking down proteins and other organic molecules, which can lead to tissue destruction or chemical burns.
To determine the acidity or basicity of each compound, we measure its pH. In simple terms, the more acidic or basic a compound is, the greater its potential for corrosivity and scarring.
Sample pH reading from one of our test subjects. 11.38 pH corresponds to an alkaline solution.
Acidic drain cleaners, particularly those with high concentrations of acid such as sulfuric acid drain cleaners, are more dangerous compared to their basic or alkaline counterparts. In chemistry, the order of addition does matter. Normally, you would gradually introduce an acid into the water, slowly increasing the concentration of the acid. Never add water to an acid As this reaction is known to generate a significant amount of heat and release dangerous smokes. See for yourself in the GIF below (and don’t try this at home).
Adding water to this beaker of sulfuric acid creates an immediate exothermic reaction, boiling the water on contact and releasing dangerous smoke into the air. Don’t try this at home!
To ensure safety during the experiments, I took necessary precautions by wearing personal protective equipment, including safety glasses, gloves, long-sleeved clothing, and a mask. The dissolution test was performed in a well-ventilated laboratory area to minimize exposure to any hazardous vapors that may be released.
Dissolution test
To begin the experiment, I weighed specific amounts of the clogging materials into separate 1,000 mL beakers:
- 4 grams of hair
- 20 grams of organic matter (10 grams of apple peels and carrot peels)
- 40 grams of butter for fat
- 14 grams of paper products (7 grams of toilet paper and paper towels)
Using a graduated cylinder, I carefully measured and added 200ml of each basic drain cleaner and 70ml of each acidic drain cleaner to the respective beakers, stirring the mixtures with a glass rod and ensuring thorough mixing with no spills. Following the instructions provided with each product, I allowed the solutions to repeat for the recommended time, usually between 15 and 30 minutes.
A crucial step in my testing was the inclusion of water, a component often overlooked in similar experiments found online. Chemical drain cleaners are designed to work in the presence of water, making it easier to transport the cleaner to the clogs and evenly distributing the solution over their surfaces, allowing the dissolving process. After the designated time had passed, I added tap water to each beaker containing the cleaner solutions and clogging materials. For basic drain cleaners (pH > 7.0), I used 500 ml of hot water at 46 degrees C, while for acidic drain cleaners (pH < 7.0), I used 700 ml of cold water at 19 degrees C.
To allow enough time for the chemicals to work, I left the samples to sit overnight and resumed testing the next morning. At this point, the samples had transformed into loba and viscous mixtures.
Hair dissolution test in progress
To continue the experiment, I employed a vacuum filtration process using a Buchner funnel connected to a 1,000 ml filter flask equipped with a pump. The contents of each beaker were carefully poured into the funnel while the pump was activated. Once the majority of the chemical drain cleaner had been removed from the funnel, I performed a water wash to remove any residual chemicals from the surface of the debris samples, ensuring that only wet solids remained in the Buchner funnel.
Our Buchner funnel, made of chemically resistant borosilicate glass, featured a perforated plate with 2 ml openings, allowing only the smallest particles to pass. In my test logic, “If a substance, solid or liquid, could pass through the 2mm openings in the filter, it was very likely to cause pipe clogging.”
On the left, our vacuum filtration setup. Liquid and dissolved solids pass through 2 mm holes in the Buchner funnel plate on the right, anything that does not pass is considered potential clogging material.
Finally, I separated the samples and subjected them to a fan drying process for a few hours to evaporate any remaining water from the wash. I recorded the final weight of each sample and compared it to its initial weight. The ratio of final weight to initial weight gave us the dissolution efficiency of each drain cleaner product.
