What could be a sign of a failing septic system?

The presence of green grass over the drain field can be a strong indicator of a failing septic system. This phenomenon occurs when excess nutrients from the septic effluent promote lush plant growth, signifying that the effluent is surfacing rather than being adequately processed by the soil. Under normal conditions, the effluent should be filtered by the soil and should not create noticeable green patches. If the grass is greener and denser over the drain field compared to the surrounding areas, it may suggest that the system is not functioning properly, allowing effluent to leak or pool above the ground.

The other options imply various conditions that typically don’t correlate directly with septic system failure. For example, consistently high water bills may indicate usage patterns but not necessarily a failing system. No odor around the system often suggests proper functioning rather than failure, and dry soil surrounding the tank usually indicates effective drainage and absorption, which is a sign of a healthy system.