If a lead-in to a building supplies a header or manifold serving 4 systems, how many main drain tests are required?

In this scenario, where a lead-in supplies a header or manifold serving multiple systems, only one main drain test is required for the entire assembly. This is because the main drain test is designed to assess the flow and functionality of the system as a whole rather than testing each individual system separately.

The testing involves examining the header or manifold's capacity to deliver an adequate amount of water to all connected systems simultaneously. If the manifold has been appropriately sized and configured, it should allow for a sufficient flow rate that meets the demands of all four systems when tested together. This approach simplifies the testing procedure and ensures efficiency in evaluating the overall performance of the water-based system.

In contrast, conducting multiple tests for each individual system may be redundant, as the primary purpose of the main drain test is to verify the coverage and effectiveness of the entire system configuration interconnected through the manifold. Therefore, requiring just one test is both practical and appropriate in this context.