All manufacturers of conventional or single stack solutions for drainage systems claim performance levels in litres of discharged water per second without a system failure.  But can we believe this data and can we compare the system of one manufacturer versus another based on a performance claim?

The problem is that there are no harmonised performance test protocols that exist today for high-rise drainage solutions. This means that the test design set-up (e.g. trap size and shape), the testing procedure (the set-up used to extrapolate testing results to a much higher high-rise) and the failure criteria (e.g. escape of one bubble of air or empty trap) are different from one manufacturer to another.

It matters because the lack of harmonised testing methods makes it impossible for engineers to truly understand which solution from which manufacturer would best fit their needs. An engineer can’t simply fall back to existing standardisation, as this was written for low- to medium-rise buildings several decades ago. As an example, if testing is conducted with a 70 mm trap instead of a 50 mm trap, the performance claim in litres per second can be as much as 20% higher. But if the product is then installed in a building with 50 mm traps and discharge of water reaching the claimed level of performance, the system will undoubtedly fail.

In short: The lack of harmonised test protocols is putting the safety of high-rise inhabitants at risk.