can i use bleach or vinegar in my greenworks gpw1804 pressure washer to clean my patio?

Diagnosis

You cannot use bleach or vinegar for cleaning your patio with this pressure washer. The Greenworks GPW1804 is a consumer-grade electric pressure washer with a detergent injection system designed only for specific, mild cleaning chemicals. Bleach (an alkaline) and vinegar (an acid) are chemically aggressive and will corrode the internal seals, pump components, and plastic detergent reservoir, causing permanent damage and voiding the warranty.

How to Fix It

To safely and effectively clean your patio, follow these steps:

1. Use only detergents specifically formulated for pressure washers. Look for products labeled as safe for electric pressure washers and for use on concrete or stone.
2. Dilute the detergent according to the manufacturer's instructions in the machine's detergent tank, using only cold or lukewarm water (never exceeding 104°F/40°C).
3. Use the low-pressure soap nozzle or setting to apply the detergent. Let it dwell on the surface for the recommended time.
4. Rinse thoroughly using the high-pressure nozzle, ensuring all detergent is washed away.

If That Didn't Work

If you need a stronger cleaning solution for tough stains like mildew or algae:

1. Purchase an oxygen-based, "oxygen bleach," or "green" pressure washer detergent that is explicitly labeled as safe for pressure washer pumps. These are effective yet much less corrosive.
2. For spot treatment, apply a dedicated outdoor concrete cleaner with a brush, let it sit, and then rinse with plain water using only the high-pressure nozzle on your washer (do not draw it through the detergent system).
3. For internal maintenance of the detergent system to remove mineral deposits, you may run a solution of distilled white vinegar and water through the detergent siphon tube and tank, followed by a clear water rinse. This is strictly for machine maintenance, not for surface cleaning.

Heads Up

Never exceed the maximum inlet water temperature of 104°F (40°C), as hotter water can damage pump seals. Always flush the detergent system with clean water after each use to prevent chemical residue from degrading internal parts. Using unauthorized chemicals risks severe damage to the pump and creates potential safety hazards from chemical reactions or spray-back.