I drew on my experience as a chemical engineer to offer insight into the effectiveness of these controversial chemicals. In my experience, I tested eight of the most commonly available chemical drain cleaners: six alkalines and two acids. I performed dissolution tests to evaluate how well each of them could dissolve pipe blockages. I had one goal: to determine which products, if any, would be effective against the most common clogging materials.
For this overview, I traveled to CNET’s Product Testing Lab in Louisville, Kentucky, to conduct a comprehensive batch distillation experiment with eight of the most commonly used chemical drain cleaners on the market. My main goal was to determine how effective each product was at dissolving various types of clogging materials, including organic matter, grease, paper products, and pet hair (the same pet hair we use to our robot vacuum testsin reality). Throughout the experiment, I also noted the pH levels of the cleaning solutions when mixed with water and monitored any changes in temperature. Additionally, I took into account 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 these 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: corrosiveness and causticity.
Corrosivity refers to the potential of a chemical substance to cause rust and deterioration of the materials that make up your piping system. Causticity, on the other hand, concerns how a chemical substance reacts when it comes into contact with organic matter, specifically degrading 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 their pH. Simply put, the more acidic or basic a compound is, the greater its potential for corrosiveness and causticity.
Example of pH reading from one of our test subjects. A pH of 11.38 corresponds to an alkaline solution.
Acidic drain cleaners, especially those with high acid concentrations like sulfuric acid drain cleaners, are more dangerous than their basic or alkaline counterparts. In chemistry, the order of addition matters. Normally, you gradually introduce an acid into the water, slowly increasing the concentration of the acid. Never add water to an acid because this reaction is known to generate a significant amount of heat and release dangerous fumess. 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, causing the water to boil 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 hazardous fumes that may be released.
Dissolution test
To begin the experiment, I weighed specific amounts of clogging materials into separate 1000 ml beakers:
- 4 grams of hair
- 20 grams of organic matter (10 grams each of apple peel and carrot peel)
- 40 grams of lard for fat
- 14 grams of paper products (7 grams each 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 into the respective beakers, stirring the mixtures with a glass rod and adding ensuring complete mixing without spills. Following the instructions that came with each product, I let the solutions sit 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 unblockers are designed to work in the presence of water, making it easier to transport the cleaner to the clogs and evenly distribute the solution across their surfaces, enabling the dissolving process. Once the allotted time was up, I added tap water to each beaker containing the cleaning solutions and clogging materials. For basic unblockers (pH > 7.0) I used 500ml of hot water at 46 degrees C, while for acidic unblockers (pH < 7.0) I used 700ml of water cold to 19 degrees C.
To allow enough time for the chemicals to work, I let the samples sit overnight and resumed the evaluation the next morning. At this point, the samples had turned into muddy, gooey mixtures.
Hair dissolution test in progress
To carry out the experiment, I used a vacuum filtration process using a Buchner funnel connected to a 1000 ml filter flask equipped with a pump. The contents of each beaker were carefully poured into the funnel while the pump was activated. Once most of the pipe cleaning chemical was removed from the funnel, I performed a water wash to remove any residual chemicals from the surface of the debris samples, ensuring that that only wet solids remain in the Buchner funnel.
Our Buchner funnel, made of chemically resistant borosilicate glass, featured a perforated plate with 2ml openings, allowing only the smallest particles to pass through. In my testing logic, “if any substance, solid or liquid, could pass through the 2mm openings of the filter, it was very unlikely to cause pipe clogging.”
On the left is our vacuum filtration setup. Liquids and dissolved solids pass through 2mm holes in the Buchner funnel plate on the right – anything that does not pass through is considered potentially obstructing material.
Finally, I separated the samples and put them through 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 between the final weight and the initial weight provided us with the dissolution efficiency of each unblocking product.
