Which of the following is NOT a critical item related to water that must be checked on a washer?

Water acidity is not considered a critical item that must be checked on a washer in the context of maintenance best practices. While water acidity can have an impact on materials and equipment over time, the more immediate operational concerns for washers typically focus on factors that directly affect the washing process itself.

Low water level is crucial because insufficient water can lead to a poor cleaning outcome. Water temperature is also a critical factor, as the effectiveness of detergents and the overall cleaning process often relies on the water being at the right temperature. Fill time is important to ensure that the washer fills adequately within a designated time frame, which impacts the entire washing cycle.

In contrast, while monitoring water acidity can be beneficial for long-term maintenance and performance, it is not one of the immediate critical items typically emphasized in washer operations and maintenance checks.