How do I use the prewash option on my washing machine?

Not necessarily. Start by checking the manual for your exact washer model: controls and the order of steps vary. Prewash may be an option added to a selected cycle, or it may work differently on another machine. Samsung notes that Pre Wash is available on some washers, not every model, and advises checking the control panel or the specific model’s manual. [S2]

Look for a section titled “Prewash,” “Pre-Wash,” or “prewash option.” Confirm whether your selected cycle permits it, what the controls do, and which detergent compartment the manual specifies. Don’t rely on instructions for a similar-looking machine.

Use the exact sequence printed for your model. As a specific example—not a universal procedure—the LG WM8000 manual says to press Power, choose the desired cycle, press PRE-WASH, and check that its indicator light is on. It describes a 15-minute prewash for heavily soiled items; afterward, choose any other desired options and press Start/Pause. [S1]

A practical way to apply that example is to pause after selecting PRE-WASH and check the indicator before starting. If the light does not come on, or the controls differ from the manual, don’t assume the feature has been selected. Recheck the manual’s instructions for your model rather than trying a guessed button combination.

Follow the detergent-compartment directions in your washer’s manual. The details matter: Samsung describes a prewash feature on some machines that uses cold water and detergent from the compartment’s Pre Wash section before the selected cycle, but that does not establish a universal detergent procedure for other washers. [S2]

Before starting, identify the compartment marked for prewash, if your machine has one, and check the manual for what it says to put there. Don’t assume the main-wash compartment is the right place or that every machine has a separate prewash section. If the manual does not specify a separate prewash compartment, avoid guessing and verify the model-specific instructions.

Use this model-specific checklist:

1. Identify the washer’s exact model from its documentation or markings.
2. Open the manual for that exact model and find its prewash instructions.
3. Check whether prewash is available and whether it is an added option or controlled another way.
4. Follow the stated cycle-selection and button sequence; confirm any indicator the manual says to check.
5. Put detergent only where that manual directs, and choose any additional options it specifies.
6. Start the washer as instructed. If the control panel or compartment markings do not match, stop and verify the instructions before starting.

For instance, if your machine is the LG WM8000, its cited manual gives the button sequence in the second answer. That example does not tell you how to set up a different LG model—or another brand. The sources here establish model variation and describe the named examples; they do not establish one preparation method that works for all washers.