Most Roundup® branded herbicides primarily contain three components – the active ingredient (glyphosate), water and a soap-like surfactant blend, which enables the active ingredient to adhere to and penetrate leaves. Application of a one to two percent solution of a Roundup® branded herbicide will provide effective weed control in most situations. This means that the vast majority of applications are more than 98 percent water.

Glyphosate is a 'non-selective' herbicide, meaning an application will kill most plants. It does this by preventing the plants from making three amino acids (components of proteins and vitamins) that are required for growth. Glyphosate stops a specific enzyme, EPSP synthase. This enzyme is found ONLY in plants and many bacteria.