The approximate pH of a drain cleaner like Liquid Plumber, which contains sodium hydroxide (NaOH) as the main ingredient, typically ranges between 13 and 14. This high pH indicates that the solution is very alkaline.
Sodium hydroxide is a strong base, and when dissolved in water, it dissociates completely into hydroxide ions (OH–) and sodium ions (Na+). The significant concentration of hydroxide ions results in a high pH value.
In general, pH values below 7 are considered acidic, pH values around 7 are neutral, and pH values above 7 are alkaline. Hence, a solution with a pH close to 14 is extremely caustic and effective for dissolving organic matter that can clog pipes.