The pH scale is a measure used to describe how acidic or alkaline a substance is, with a range that goes from 0 to 14. A neutral substance, like pure water, sits exactly at the middle with a pH of 7. Anything below 7 is considered acidic, while anything above 7 is considered alkaline, also known as basic. Many common household items, from lemon juice to baking soda, fall somewhere on this spectrum. Dish soap is a frequent subject of curiosity because of its effectiveness in removing tough grease and food residue. Understanding the pH of dish soap can offer insight into its cleaning power and its potential effects on the skin.
The pH Range of Common Dish Soaps
Most standard liquid hand-washing dish soaps fall into a range that is neutral to slightly alkaline, typically between pH 7 and 10. Many popular grease-cutting formulas are slightly more alkaline, often landing around pH 8 to 9. This mild alkalinity is a deliberate choice made by manufacturers to balance cleaning performance with safety for household use.
Some specialty or “gentle” formulas are specifically designed to be closer to neutral, sometimes registering between pH 7 and pH 8. True high alkalinity (pH 11 or higher) is uncommon in products intended for hand-washing dishes. These higher pH levels are typically reserved for heavy-duty industrial cleaners or automatic dishwasher detergents.
How pH Impacts Cleaning Effectiveness
The slightly alkaline pH of dish soap plays a direct role in its ability to remove food residues, particularly fats and proteins. Alkalinity assists in the process of saponification, which is the chemical reaction that converts fats and oils into soap. This reaction is important because most common kitchen grease is fat-based, and the alkaline solution helps to chemically break down these stubborn oils.
The alkaline environment helps the surfactants—the main cleaning agents in soap—work more efficiently. The detergent molecules are more effective at lifting and suspending oily particles when the water is slightly alkaline. While acidic cleaners are effective at dissolving mineral deposits, dish soap’s mild alkaline composition ensures it is optimized for cutting through the organic matter left on plates and cookware.
The Effect of Dish Soap pH on Skin Health
The skin has a natural protective layer called the acid mantle, which maintains a slightly acidic pH, typically ranging between 4.5 and 5.5. This acidity is a defense mechanism that helps maintain the skin barrier function and supports the growth of beneficial microorganisms.
When dish soap with a pH above 7, even a mildly alkaline one, comes into contact with the skin, it raises the surface pH. This shift temporarily disrupts the delicate balance of the acid mantle.
Using alkaline soap can interfere with the skin’s natural barrier repair functions and increase transepidermal water loss (TEWL). TEWL is the measure of how much water evaporates from the skin’s surface, and an increase indicates that the skin’s moisture barrier has been compromised. This disruption can lead to feelings of dryness, tightness, and potentially cause irritation or dermatitis with frequent use. Manufacturers address this by formulating “gentle” dish soaps closer to a neutral pH, sometimes including moisturizers to help mitigate the drying effects of even mild alkalinity.