Dishwashing detergent dissolves grease better than plain water because dishwashing detergent can be mildly alkaline, which helps break down and remove greasy dirt.

Verified by Lenz · May 18, 2026

The Short Version

Dishwashing detergent does remove grease better than plain water, and mild alkalinity can help loosen fatty soils. But the main reason detergents work is usually their surfactants, which let oil mix with water and rinse away. The claim is broadly accurate, but it gives alkalinity more explanatory weight than it usually deserves.

Caveats

Surfactants, not alkalinity, are usually the primary mechanism behind grease removal in dish detergents.
Many hand dishwashing liquids are only slightly alkaline or near neutral, so pH-driven fat breakdown is limited in many formulas.
Automatic dishwasher detergents are often much more alkaline than hand dish soaps, so their cleaning chemistry is not directly interchangeable.

The Receipts

Effects of alkalinity of household dishwashing liquids on hand skin
PubMedJan 1, 2001
Secret Science of Soaps & Detergents
American Chemical SocietyMay 1, 2023
Dishwasher Detergent Facts
Sub-Zero
Sodium lauryl sulfate
PubChem (NIH)
Chemistry and cleaning mechanisms of dishwashing detergents (relevant literature corpus)
PubMed Central
Detergent
ChemEurope
Glossary of Cleaning Product Terminology
American Cleaning Institute
When Water Won’t Work
Woods Hole Oceanographic InstitutionJan 10, 2017
Surfactants
American Cleaning InstituteAug 30, 2022
An alkaline liquid hand dish washing detergent composition
Google PatentsJul 13, 2011

+ 13 more sources — see the full list on Lenz