I have seen a lot of posts about how to plumb in both a dishwasher and a washing machine, before and after the sink trap.

What is stopping me installing the following:

1. a simple shallow bottle trap underneath the sink to make use of the cupboard space http://tinyurl.com/jubtf

2. the 2 appliance waste pipe connect after the trap using http://tinyurl.com/jn25n

3. a running trap is then installed down the run, to potentially stop drain smells coming out of the appliances http://tinyurl.com/geiz

Would you actually need the trap below the sink if I have a running trap further down the run?