Water-based drilling mud most commonly consists of bentonite clay (gel) with additives such as barium sulfate (barite), calcium carbonate (chalk) or hematite. Various thickeners are used to influence the viscosity of the fluid, such as glycol, carboxymethylcellulose, polyanionic cellulose (PAC), or starch.

In turn, deflocculants are used to reduce viscosity of clay-based muds; anionic polyelectrolytes (e.g. acrylates, tannic acid derivates, lignosulfonates (Lig), polyphosphates) are frequently used. Red mud was the name for a Quebracho-based mixture. Other components are added to provide various specific functional characteristics as listed above.