The Best Chemical Drain Cleaners for 2025
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 commonly used chemical drain cleaners on the market. My primary goal was to determine the effectiveness of each product in dissolving various types of clogging materials, including organic matter, grease, paper products, and pet hair (the same pet hair we use to our robotic vacuum testsactually). During the experiment, I also noted the pH levels of the cleaning solutions when mixed with water and observed any temperature changes. I also 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 divided them into acids and bases. As you may remember from high school chemistry, acids are compounds that give off a hydrogen ion (H+) when mixed with water and have a pH lower than 7. On the other hand, bases are compounds that accept these ions (or hydroxide, OH- ions) and have a pH higher than 7. Understanding this distinction is critical because of two important factors associated with these products: corrosivity and corrosiveness.
Corrosivity refers to the potential of a chemical to cause rust and deterioration of the materials that make up your piping system. Causticity, on the other hand, refers 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 any compound, we measure their pH. In simple terms, the more acidic or basic a compound is, the greater its potential for corrosiveness and corrosiveness.
An example pH reading from one of our test subjects. 11.38 pH corresponds to an alkaline solution.
Acidic drain cleaners, especially those with high acid concentrations such as sulfuric acid cleaners, are more dangerous than their basic or alkaline counterparts. In chemistry, the order of addition matters. Typically, you gradually add acid to the water, slowly increasing the concentration of the acid. Never add water to acid as this reaction is known to generate a significant amount of heat and emit hazardous 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, boiling the water on contact and releasing dangerous fumes into the air. Don’t try this at home!
To ensure safety during the experiments, I took the necessary precautions by wearing personal protective equipment, including safety glasses, gloves, long-sleeved clothing, and a mask. The dissolution test was conducted in a well-ventilated laboratory area to minimize exposure to any hazardous fumes that may be released.
Dissolution test
To begin the experiment, I weighed certain amounts of the plugging materials into individual 1000 ml beakers:
- 4 grams of hair
- 20 grams of organic matter (10 grams each of apple peels and carrot peels)
- 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 to the respective cups, stirring the mixtures with a glass rod and ensuring complete mixing without spillage. Following the instructions provided with each product, I let the solutions sit for the recommended time, usually between 15 and 30 minutes.
A crucial step in my test 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, which facilitates the transport of the cleaner to the blockages and evenly distributes the solution over their surfaces, enabling the dissolution process. After the allotted time was up, I added tap water to each cup containing the cleaning solutions and plugging 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 give the chemicals enough time to work, I let the samples sit overnight and re-evaluated the next morning. By this point, the samples had turned into muddy, slimy concoctions.
A hair dissolution test is performed
To proceed with 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 cup were carefully poured into the funnel while the pump was activated. After most of the chemical drain cleaner was drawn from the funnel, I performed a water flush to remove any residual chemicals from the surface of the debris samples, making sure that only wet solids remained in the Buchner funnel.
Our Buchner funnel, made of chemically resistant borosilicate glass, featured a perforated plate with 2 mm holes allowing only the smallest particles to pass through. According to my test logic, “if a substance, solid or liquid, can pass through 2 mm holes in the filter, it is very unlikely to cause a tube blockage.”
On the left, our vacuum filtration setup. Liquids and dissolved solids pass through 2 mm holes in the Buchner funnel plate on the right — anything that doesn’t pass is considered potential plugging material.
Finally, I separated the samples and subjected them to a fan drying process for several hours to evaporate the remaining water from the wash. I recorded the final weight of each sample and compared it to the initial weight. The ratio of final weight to initial weight provided us with the dissolution efficiency of each drain cleaning product.
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