What is a common sign of a failing septic system?

Pooling water in the yard is a common sign of a failing septic system because it indicates that the wastewater is not being properly treated or absorbed into the soil. A functioning septic system relies on the effective dispersal of effluent into the drain field, where it is filtered and treated naturally by the soil. When the system fails, the effluent can rise to the surface, creating pools of water in the yard. This not only represents a sign of system malfunction, but it can also pose health hazards and environmental risks due to untreated wastewater coming into contact with the surface.

In contrast, the other options indicate more positive or non-problematic conditions. Strong chemical smells may suggest an issue, but they do not specifically signify failure. Healthy grass growth could suggest adequate drainage and nutrient presence from the septic system, while high-quality effluent discharge indicates that the system is functioning well, rather than failing.