depends on where you have your tapware..if you have your tap from the wall then your plumbing is hidden.

if you have your tap on the basin itself then the plumbing is on the outside..ie waste trap and water connections..

this is one where it's a wall connection much neater and nicer looking.

this is when it's a tap on the basin itself more messy looking..

I'm of no help then as I've got both going in two different homes..the first I've lived in for 4 years no problems as yet the second only recently no problems either :)

this is my Reno photo..it shows where they hook the chrome bottle trap on.

so logically your bottle trap is what you see in your cupboard anyway just the prettier version..as your waste will then go into the wall or underneath into the floor..no difference

Kazawa

This bathroom has all the hallmark of a designer, if you have engaged a designer keep quality throughout, don't try to get the renovation on the cheap.

Your designer has created a duct for services, modern plumbing is designed to last,

the the majority of patented joining of copper pipes have a 25 year warranty.

If you want perfection to last 25 yr +, Architects and quality bathroom renovations specify silver soldered ( brazed ) copper water pipes, and new pvc drainage pipes.

It really is a case of you get what you pay.

A plumber may take 8 hrs to rough in a bathroom with

copper, silver soldered x $ 90/hr = $ 720 + materials= $ 1000

Or copper/ plastic with fittings $ 5 hrs x$ 90=$ 450 +materials $ 400 =$ 850

Only use taps/mixers with 15 year warranty e.g Grohe, Sussex, Methvan from $ 300e

Bath steel Kaldewei Eurowa $ 400, 15 yr warranty

A quality tiler will cost approx $ 3,000+--

Waterproofing , get it done professionally, to waterproof a bathroom exceeding Building Code of Aust usually takes 3 visits from waterproofer and will cost approx $ 1250 to $ 1500 with waterproofing certificate. and take 5 days, waterproofing is considered a structural component for home warranty insurance

Only buy tiles from reputable tile shops, a tiler can only do his beat with quality tiles, if you give him rubbish tiles you get a poor job.

Tilers in Sydney buy their less expensive tiles at Sefton

A bathroom of the quality in the photo renovated properly/ professionally would set you back all up approx $ 30K + depending on vanity/ bench top, toilet suite

Ken Evers Beach Bathrooms

You haven't said why you are choosing this type of basin set up. I have worked hard to find a similar thing, needing a wheelchair accessible basin where the pipes underneath don't get in the way of knees and also allows room for the feet section on a wheelchair. We have chosen the Opal 900 twin wall basin, which has the added advantage of sides. We have a double wall so did not need to consider the issue you have, but I would suggested a hinged false wall, under the basin only, that is not tiled, just painted. It could also double as a skinny cupboard for things you don't need to access often.