Potential smell issue with regards to previous tundish question?

Question from Steve Lumb, via email:
Looking at your answer to the tundish issue, would the smells not come back as this should be trapped with a waterless trap?

Answer from Martyn Bridges, director of marketing and technical support at Worcester, Bosch Group:
If the waste water system is connected to the household soil and vent system then there is no real way around this other than having a service regime whereby the trap you have created is periodically “topped up” with water.

If the waste water system is rather like a singular or even basin waste that empties over an open drain and then onto the main sewerage system then it would be unlikely you would encounter any smells etc…