Detergent chemicals are commonly used in pressure washing. These include citric acid (for concrete driveways and stain removal), sodium Hydroxide (caustic), sodium Hypochlorite (disinfectant), ammonia, and oxalic acid. Two of these chemicals--sodium Hypochlorite and sodium Hydroxide--combine to make bleach, which is also commonly mixed with water, or used on its own, to make a cleaning/disinfectant solution. Using chemicals is required for pressure washing. There are soaps made of natural materials that are considered more eco-friendly.