When we conduct workshops and discuss inspecting and installing sewage tanks, we always stress that they need to be watertight. This usually leads to quite a discussion of what constitutes watertight, why it is important, and what happens if tanks are not watertight.Watertight means water does not leak into or out of the tanks. If the leakage is from the tank out, sewage escapes into the soil. Since it is introduced as saturated flow, it can move into shallow groundwater or through bedrock fissures and become a source of contamination.If water leaks or flows in, excess water is introduced to
