Water Treatment Operator-in-Training (OIT) Practice Test 2025 – The Complete All-in-One Guide to Success!

A cross connection refers to any physical connection between a potable (safe drinking) water supply and a non-potable source, which could lead to contamination of the drinking water supply. The scenario involving a connection between a boiler and a domestic water line is an example of a cross connection because, in this case, there is potential for water from the boiler, which may not be safe for consumption, to enter the drinking water supply. This type of connection poses a significant risk of backflow, where contaminated water could flow back into the clean water system, compromising the safety of the potable water.

In contrast, the other examples listed do not represent a cross connection in the same way. For instance, the connection between a water source and a fountain typically involves pressurized water intended for consumption and would not inherently create backflow risks. Likewise, the connection between a sink and a dishwasher is usually designed to ensure that waste water from the dishwasher does not contaminate the clean water supply. A connection between a water main and a fire hydrant is typically regulated and designed to prevent backflow as well, ensuring that the fire protection system does not adversely affect the potable water system. Therefore, the correct answer highlights a scenario that poses a true risk of contamination within a water