On the picture the dishwasher will go on the right hand of the cabinet where the water and waste pipe is. Where should I drill the cabinet . On the bottom of the cabinet ? Or on the lower part of the back panel?
High up on the back right-hand side (in the hardboard back panel not the MFC backrail)- the drain hose should rise to the level of the underside of the worktop to prevent your sink draining into the dishwasher sump. Cut a 'U' into rear edge of the side panel & corresponding hole into the back panel - large enough to feed the anti-flood head through.
I'd normally route them up through the void a the back of the unit then exit high up on the back panel. I don't think that you've enough space to get the head of the supply pipe past the two runs of copper clipped to the wall.
Thinking about it, it might be worth checking that there is sufficient space behind the machine (at high level) to run the waste/supply as I suggested. If not then cut the back panel of the adjacent unit below the copper pipes, bring the d/w pipework up through the void to enter the unit through the back panel. I'd try to avoid cutting holes in the base of the unit mainly because it looks cr*p and things inevitably end up falling into the hole. Whatever you do, make sure that the waste pipe runs as high as possible inside the unit to prevent grey water from the sink running into the d/w.
Out of interest, where is the mains (power) supply for the machine?
I would fit the sink and the waste first, and then see where the trap and connectors are set. I normally drill towards the top, so that water doesn't sit in the bottom of the pipe and then stagnate - although it'll allways sit somewhere in the pipe. If you drill it into the very rear of the unit, you then have to feed it through the back panel, but if you drill the hole forward of the back panel, then the dishwasher may not go back as far as it could. This is a very subjective situation, and there's no hard and fast rule, but I can see the flexibility of coming up through the bottom of the unit.
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