Is a U-bend required for the waste hose?

[WashingMurchine]

My washing machine drainage hose stretches and just joins (with the aid of elbow grease and a jubilee clip) to the under-sink drainage point. Therefore, from the sink attachment, the hose makes its way to a hole in the unit that is slightly lower than the connection point. Behind the unit, it then drops down to the base of the machine at its regular exit point. Included with the hose is a U-bendy thing that holds the hose in a U shape. I have taken this off to allow connection to the sink. Does the hose require an upside down U-bend in it for any reason or am I okay to proceed with the way I have it connected?
Without this, I am thinking that there may be problems with sink waste travelling down the washing machine pipe.
Furthermore, I have had the machine for two days and I am beginning to get a sore ear. I have located the problem for this though and have had a chat with my wife.

[tiredengineer]

If you get any restriction in the drain under the sink it will definitely back up into the washing machine.



Unplug your appliance before working on it.