What is the outcome when chlorine treatment efficiency decreases?

When chlorine treatment efficiency decreases, it means that the process of disinfecting the water is not as effective as it should be. Chlorine is used to kill or inactivate pathogens in the water, ensuring that it is safe for consumption and use. If the efficiency of chlorine treatment plunges, it can lead to a situation where harmful bacteria, viruses, or other microorganisms remain in the water supply.

In this case, the overall effectiveness of the water treatment system is compromised, resulting in inadequate disinfection. This can pose health risks to consumers, as the water may still harbor harmful contaminants. Hence, when the efficiency of chlorine treatment decreases, water treatment becomes less effective, making this the correct answer.

The other options reflect misunderstandings of the chlorine treatment process. Water remaining contaminated directly relates to the ineffective disinfection process but does not fully encapsulate the broader issue of treatment efficacy. Similarly, water treatment not improving (which is implied in the third option) is not indicative of a situation where the system has failed instead, it is about the overall inefficiency. Higher chlorine levels (as suggested in the last option) are not a direct outcome of decreased efficiency; rather, it indicates a potential overcompensation for the inefficiency.