Drain Cleaning Classifications

Drain cleaners may be categorized into four major groups, which include: acids, oxidizers, caustics and enzymatic. Let’s take a look at the attributes of each.

An acid is generally defined as any substance that increases the concentration of hydronium ion ([H₃O+]) in solution.  Acid drain cleaners work because a chemical reaction occurs between the hydronium ion and whatever material is blocking the drain and the heat that is released as the solution itself mixes with the water in the pipes. For example, if grease is clogging a drain, it is necessary that the reaction created in an acidic drain cleaner be sufficient enough to liquefy the grease so that it will drain. This simplistic example explains the acidic reaction needed to clean drains. Simply, the lower an acid’s pH (on a scale of 0 to 7), the higher its acidity. The more acidic the drain cleaner, the higher the likelihood of a “vigorous reaction.” This is of course, completely dependent upon the chemical composition of whatever is blocking the drain, as well. But you get the idea…

Oxidation (the loss of electrons) and reduction (the gain of electrons) are associated chemical reactions. In general, whenever one substance loses electrons, another substance picks them up.  Oxidizing agents include nitrates, chlorates, perchlorates, hypochlorites and peroxides.  When organic compounds (plants, vegetables, paper, etc…) make up the material that is blocking the drain, they may react strongly to the oxidizers in the drain cleaner and create heat and gas that subsequently help clear the drain. Oxidizing materials such as sodium hypochlorite are often added to caustic drain cleaners to dramatically increase their effectiveness.

A caustic, or base, is basically a substance that increases the concentration of hydroxide ion ([OH-]) in solution that contains water. Caustic drain cleaners react similarly as acid drain cleaners, except hydroxide ions provide the driving mechanism for the reaction.

Caustic drain cleaners can be either liquid or granular in form. Generally, aqueous solutions are composed of dissolved sodium hydroxide, and are therefore denser than water. Granular forms are usually composed of sodium hydroxide and often contain aluminum particles. These particles react with water to release small amounts of hydrogen gas which generates more heat and adds force to the unblocking effect of the drain cleaner. In order to perform well, caustic drain cleaners must be very close to the blockage and must react with the material that is blocking the drain.

Enzymatic drain cleaners use biological/enzymatic forms of chemical reactions to "metabolize" materials in the blockage and therefore clear the blockage. These reactions generally are:

Enzymatic drain cleaners usually contain dried products consisting of enzyme preparations, bacterial cultures, and fillers. They are not corrosive and do not cause disease. However, past surveys have detected the presence of salmonellae in these drain cleaners.  Many enzymatic drain cleaners originated in the biological treatment industry (e.g., septic tank treatment, waste water treatment) and have only recently entered the consumer market place.