no comments by anyone else on whether they find this washing machine connection good ? to avoid sink feedback
Need the tube to loop far higher. Our dishwasher is plumbed in like this and goes up under the work top. The sink has two bowls and the connection is to the smaller draining sink.
Issue is that water from an emptying will find the easiest path. Also check the sink for constriction (fat, hair, etc).
Lastly - the Mrs uses Calgon in each wash and the plumber on the kitchen refit commented that the washing machine and dishwasher looked like new tablets (the dishwasher gets a finish clean pack on an intense 70degC wash every 3-6 months)