What can happen if a septic tank is pumped during a wet period?

Pumping a septic tank during a wet period can lead to the tank floating out of the ground due to the hydrostatic pressure exerted by the surrounding saturated soil. When the ground is wet, moisture content is high, and the buoyancy effect can become significant. If the tank is emptied of its contents, the weight that normally anchors it in the ground is reduced. This can cause the tank to displace enough soil and water to become buoyant and potentially rise to the surface, which is a serious issue that can lead to damage to the tank, plumbing and the surrounding area.

The other scenarios, such as overflowing or cracking, may occur under different circumstances, but the unique combination of factors during a wet period primarily predisposes the tank to floating if it is pumped. As it floats, it may not only come out of the ground but can also disrupt the septic system's overall function and repair can be costly and complicated. Therefore, it is crucial to consider the condition of the soil and groundwater before deciding to pump a septic tank.