Walk-in shower drain options, linear strip versus tiled centre drain

Ask this question in any renovation forum and you get a split room. Half the replies say linear drains look fantastic, the other half say they are revolting to clean. Both camps are right, which is why the decision is harder than it looks.

Here is what actually decides it, and it is probably not the thing you are weighing up.

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Your tile size has already chosen for you

This is the part people discover too late, and it overrides almost every other preference.

A centre drain needs the floor to fall towards a single point from all four directions. That means each tile around the drain has to twist slightly, which is only possible with small tiles. With a 600 by 600 tile, you physically cannot create a four-way fall without cutting the tile into wedges, and it will look like you tried.

So the rule of thumb is simple. Large format tiles push you to a linear drain. A centre drain wants mosaics or small format tiles in the shower floor, which is a look you either want or you do not. Our wastes and outlets ranges cover both.

The compromise worth knowing

You can run large format tiles through the rest of the bathroom and switch to a small format inside the shower, which keeps the centre drain option open and reads as a deliberate design decision rather than a compromise. Plenty of good bathrooms do exactly that.

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What you cannot do is choose 600 by 600 everywhere and then ask for a centre drain. Decide the tile and the drain in the same conversation, because they are one decision wearing two hats.

The cleaning reality, honestly

We would rather say this plainly than let you find out in month two.

Linear drains collect hair. Not a little, a lot. The channel is long, it sits flush with the floor, and everything that goes down the shower ends up lying along it. People who have them describe weekly cleaning as the realistic minimum, and the phrase that comes up over and over is lovely in theory, disgusting in practice.

A centre drain collects the same hair, but in a smaller spot, and the grate lifts out in one piece. It is less to clean because there is less of it. The round chrome floor grates and square tile insert grates are the two common centre-drain finishes.

That said, this is a maintenance preference rather than a defect. Everyone who owns a linear drain and cleans it regularly is perfectly happy. The people who regret it are the ones who did not expect the job.

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Side by side

Note the screeding row, because it runs against the usual assumption. A linear drain is easier to get right since the floor falls one way in a single plane. A centre drain asks more of your tiler, and a mediocre centre drain is far more obvious than a mediocre linear one.

V channel or flat bottom

If you go linear, this is the one spec worth caring about.

A V-shaped channel funnels water to the outlet and holds very little standing water once the shower stops. A flat-bottomed channel retains a thin film along its length, which is where smell and biofilm come from.

So the V profile is the better choice, and it is usually the cheaper one to live with even where it costs a little more to buy. Ask which profile you are being quoted, because it is not always stated.

Whichever you choose, insist on WaterMark certified product, which confirms a plumbing item has been assessed as fit for purpose and authorised for use in a plumbing installation. Channel drains are exactly the category where cheap uncertified imports turn up.

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Falls, and the number to hold your builder to

Same requirement for either drain type, and it is not a matter of opinion.

A floor waste must be installed in the shower area, with a minimum fall to the waste of 1 in 80 and a maximum of 1 in 50 under clause 10.2.12 of the Housing Provisions.

In site terms, 1 in 80 is about 10mm of drop over 800mm, which is the figure experienced tilers quote from memory. There is a maximum as well, so you cannot simply pile on more fall to be safe. Too steep feels wrong underfoot and shows up as lippage along a linear drain.

For the construction detail behind it, the code gives you two routes. NCC 2022 reinstated the construction details into the code itself, with AS 3740 retained as an option, and AS 3740-2021 is the current edition of the waterproofing standard for domestic wet areas.

The step-down question, settled

This one causes genuine confusion, and you will see both 2mm and 25mm quoted confidently by different people.

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Here is the actual position for a doorless shower. A water stop must be placed at least a 1500mm horizontal radius from the shower rose connection of an unenclosed shower, with the waterproofing running from the water stop back to the waste, and the waterstop termination for unenclosed showers must be flush with the finished floor level at the perimeter of the shower area.

Read that carefully. For an unenclosed shower the water stop is required, and it terminates flush with the finished floor. So the thing you need is not a step you can trip on, it is a correctly installed waterstop angle at the right position with the membrane bonded to it.

Why people remember a step

Hobs and step-downs are a traditional way of containing water in an enclosed shower, and plenty of older bathrooms have one. They are a legitimate approach, just not the only one, and not what the unenclosed shower provisions call for.

The other thing worth knowing is where that waterstop lands. The 1500mm radius is measured from the rose, not from your glass panel, so on an open shower it will often sit further out into the room than you expect. Several people end up waterproofing the whole bathroom simply because it is easier than chasing a curved line across the floor, and that is a perfectly sensible call.

State variations apply here, so confirm with your own building surveyor or certifier before anyone screeds.

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Getting it installed properly

Both options are unforgiving of poor workmanship, and the failure mode is expensive.

• Use a plumber who has done the specific drain type. Linear drains in particular reward experience.

• Set the drain position against the tile layout. A linear drain should align with a grout line or a wall, never land mid-tile.

• Confirm the falls with a level and water. Not by eye, and not after tiling.

• Check the waterstop position before waterproofing. Moving it afterwards means starting again.

• Insist on a membrane inspection with photos. This is the last time it is visible.

• Get the compliance paperwork. In New South Wales that means a certificate of compliance for notifiable work, with equivalents elsewhere.

The drainage connection itself is licensed work. AS/NZS 3500.2 covers sanitary plumbing and drainage, and a shower drain connection sits inside it.

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So which one

A straight recommendation rather than a shrug.

Choose a linear drain if you want large format tiles, you want the clean modern look, and you are honestly fine with a weekly clean. Position it along the glass line or against the wall rather than mid-floor.

Choose a centre drain if cleaning is your priority, you are happy with small format tiles in the shower, and you have a tiler you trust to get a four-way fall right.

If you are still torn, the cleaning question is the one that predicts regret. Nobody has ever regretted a drain being easier to clean.

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The short version

• Tile size usually decides the drain, not the other way round.

• A 600 by 600 tile cannot form a four-way fall to a centre point.

• Centre drains need small format tiles or mosaics in the shower floor.

• You can switch tile format inside the shower as a deliberate detail.

• Linear drains collect hair and need frequent cleaning.

• Centre drains are less to clean because the area is smaller.

• Linear drains are actually easier to screed, since the fall is one plane.

• A V-shaped channel holds less standing water than a flat bottom.

• Falls must sit between 1 in 80 and 1 in 50.

• 1 in 80 is roughly 10mm of drop over 800mm.

• For an unenclosed shower the waterstop terminates flush with the finished floor.

• The waterstop sits at a 1500mm radius from the rose, not from the glass.

• Many people waterproof the whole bathroom because it is simpler.

• Use WaterMark certified drains and a plumber experienced in that type.

• Align a linear drain with a grout line or wall, never mid-tile.

Both options work when they are installed properly, and both fail badly when they are not. If you want to see the grate profiles in person and work out what suits your tile choice, come and see us in Adelaide or book a showroom appointment and bring your tile sample.