Short answer
The sink module carries the bowl, the trap and the waste outlet, and it is the module that forces the drainage decision. Where the waste goes — a drain, a soakaway, or a tank — has to be settled before the run position is fixed, because waste does not run uphill.
Why the sink module is different
It has to accept a bowl, a trap beneath it and a waste outlet through the side or the rear. The internal structure therefore differs from a storage module: less shelving, more clear space, and an outlet route.
This is also why the sink belongs at the working end nearest the door rather than at the far end where the waste route is usually ad hoc.
The drainage decision
Three routes. Connected to a house drain, which is best and needs the run within reach of one. A soakaway, which works where the ground allows and the volume is low. A tank or a bucket, which is honest for a bar sink that sees occasional use.
None of these can be solved after the run is positioned. A sink two metres from any drain is a problem that gets expensive.
What we supply and what we do not
We supply the cabinet with the sink opening and the outlet route. The bowl, the tap, the trap and the plumbing are supplied locally or quoted as separate lines.
Indoor taps are commonly used outdoors and commonly fail there — the cartridge is not frost-tolerant. A frost-proof outdoor tap is worth the small extra.
Winter
An outdoor sink in a frost area needs to be drained down and the trap emptied before the first freeze, or the trap and the cartridge will split. This is not a cabinet problem, but it is a reason people choose a simple trap-free bar sink for cold climates.
The drainage details that matter
The waste leaves below the shelf
A trap has to fit behind the cabinet, not under the shelf. On a 656 mm deep module that is roughly 120 mm of usable depth behind the back panel.
Fall matters more than pipe size
A short waste with a consistent fall drains; a long flat one silts up. The run to the gully is measured, not estimated.
A flexible hose keeps the module mobile
On a castor run the waste is a flexible connection to a local gully, so the module can still be rolled out for cleaning.
Drain the trap before winter
Standing water in a trap splits it. That is the single most common water damage inside an outdoor cabinet, and it is not a cabinet fault.
An outdoor-rated tap
Frost and UV are what a tap has to survive. The top is drilled and braced for a standard 35 mm tap, and the tap itself is chosen locally.
Questions we get about this
Where does the waste go?
That is a site question and it is the one to answer first: a house drain, a soakaway, or a tank. We build the outlet route; the connection is local plumbing.
Can I use an indoor tap?
You can, and it often fails outdoors because the cartridge is not frost-tolerant. A frost-proof outdoor tap costs a little more and lasts.
Does the sink module need a different depth?
No. The 656 mm depth is unchanged. The difference is internal — clear space for the trap instead of shelving.
Before you order anything
Send the grill model and the run length. You get the aperture, the module list and one itemised price back in writing — freight shown separately, valid 15 days.