Texas Commission on Environmental Quality (TCEQ). Class C Water License Exam

What is the primary cause of main line failures in a distribution system?

1. Heavy rains

2. Internal and external corrosion

3. Poor water quality

4. Inconsistent flow rates

The correct answer is: Internal and external corrosion

The primary cause of main line failures in a distribution system is internal and external corrosion. Corrosion occurs when metal pipes react with water or environmental elements, leading to deterioration of the material. Over time, this process weakens the pipes, making them more susceptible to leaks and ruptures. Factors such as the composition of the pipe material, water chemistry, and soil conditions can all contribute to the rate of corrosion. Heavy rains may lead to increased pressure on the pipes or flooding, but they are not typically the root cause of the degradation of the pipe material itself. Poor water quality can cause issues, but it usually manifests as secondary effects rather than being the direct cause of line failures. Inconsistent flow rates can cause water hammer or other pressure fluctuations, but these usually do not lead to main line failures as directly as corrosion does. Therefore, internal and external corrosion remains the primary concern when examining the integrity and longevity of distribution system infrastructure.