Household bleach is a common product found in most homes, primarily used as a disinfectant and a potent laundry whitener. The active ingredient responsible for its cleaning and germ-killing properties is a chlorine-containing compound. This concentration is precisely measured for both effectiveness and safety, and understanding it is important for proper dilution and application.
The Chemical Identity of “Chlorine” in Bleach
The name “chlorine bleach” can be misleading, as household liquid bleach does not actually contain elemental chlorine gas (Cl2). The active substance is a chemical compound called sodium hypochlorite (NaOCl) dissolved in water. This compound is the sodium salt of hypochlorous acid, and its chemical formula includes one atom of chlorine, one of oxygen, and one of sodium.
The product is referred to as “chlorine bleach” because the hypochlorite ion (ClO-) readily releases a form of chlorine that acts as a strong oxidizing agent. This oxidation process effectively destroys germs, neutralizes odors, and removes stains by breaking down the chemical bonds of organic materials. The concentration is measured by the percentage of sodium hypochlorite present by weight.
Typical Concentration in Household Bleach
For many years, the standard strength for household bleach was 5.25% sodium hypochlorite by weight. Today, manufacturers have increased this concentration, and most standard liquid bleach products now contain between 6.0% and 6.15% sodium hypochlorite. This percentage represents the amount of the active ingredient relative to the total volume of the solution, which is mostly water and small amounts of stabilizing agents.
The concentration is chosen to optimize both the stability and the effectiveness of the product for general consumer use. To prevent the sodium hypochlorite from decomposing too quickly, a small amount of sodium hydroxide is added, which helps maintain the solution’s alkalinity. Even with these stabilizers, the bleach concentration will slowly degrade over time, particularly when stored in warm conditions or exposed to light.
How Bleach Concentrations Vary by Product Type
The concentration of sodium hypochlorite can differ significantly depending on the product’s intended purpose. “Concentrated” bleach formulas, which are now widely available, often contain a higher percentage of the active ingredient, typically around 8.25%. This higher concentration means the consumer needs to use less product to achieve the same level of disinfection.
Specialty products, such as “splash-less” or gel-based bleach, may have different formulations that affect the available concentration. Industrial or commercial-grade solutions used in water treatment or specialized cleaning can be much stronger, reaching concentrations of 10% to 15%. Color-safe bleach products do not contain sodium hypochlorite, relying instead on hydrogen peroxide or other non-chlorine ingredients.
Practical Application: Dilution and Safe Use
The concentration of the bleach dictates the proper dilution required to achieve an effective sanitizing or disinfecting solution. For general sanitizing of non-porous surfaces, a simple dilution of about four teaspoons of household bleach (at 6% to 8.25% concentration) mixed into one quart of water is often sufficient. This mixture yields a solution of approximately 500 to 800 parts per million (ppm) of available chlorine.
A stronger dilution is required for high-level disinfection, such as cleaning up bodily fluid spills or disinfecting surfaces during an outbreak. This typically involves a ratio of one part bleach to nine parts water. For the bleach to work properly, the diluted solution must remain on the surface for a specified contact time, usually one to ten minutes, before being rinsed away. Since the active ingredient quickly degrades once mixed with water, diluted solutions should be prepared fresh daily for maximum effectiveness.