Commercial Kitchen Drainage: Floor Wastes & Grates

Mop out a commercial kitchen for a few nights and you'll spot it straight away — some floor drains were fitted with care, others weren't. Three things have to line up before the drainage will actually work. Before any fixture gets picked, the trade waste agreement for the grease arrestor needs sorting first. Next, the floor wastes must match the pipework in size. Finally, position clear outs so a licensed plumber can get to the line without tearing up tiles.

An independent plumbing educator explains why installing clean-outs above certain drain fittings eases future unclogging, relevant background for commercial kitchen drainage access and maintenance.
Video Credit: gregvancom

Commercial Kitchens: Why Drainage Matters

Water, oil, debris and constant wash-down hit a commercial kitchen floor much harder than any residential bathroom floor ever would. Wash-downs happen often, water and oil and debris land on the floor all through trading hours, and the floor has to be dry again before the next service — small wonder designers and health inspectors both treat drainage as a priority.

Get the drainage design wrong and whoever runs the kitchen day to day pays for it — slow floor wastes, blockage call-outs, the lot. Get a licensed plumber involved early, sort the layout and fittings properly, and most of that hassle simply won't happen.

Three stainless steel floor drains with square grates and circular clamp fittings

Trade Waste and Grease Arrestors

Before a floor waste can be installed, the food business needs to obtain authorisation from the relevant water authority to discharge wastewater to sewerage systems. This usually comes in the form of a trade waste agreement or permit, and will typically include a grease arrestor of a size determined by the water authority in your area. Sydney Water, for example, says if you prepare or serve hot food you need a grease trap and trade waste agreement. Requirements differ between water authorities, so check with your local water authority or plumber for the rules in your area.

Your licensed plumber will take care of this on your behalf well before you choose any fixtures. Sanitary drainage connections, drain falls and vent sizes for commercial projects follow the Australian plumbing standard, AS/NZS 3500.2. Plumbing on all commercial projects is done by licensed plumbers in accordance with the plumbing legislation in your state or territory and this is certainly not a DIY job.

Worth repeating: a strainer basket floor waste is NOT a grease trap. Grease trap installation is a separate matter, handled by your licensed plumber and the water authority.

Long stainless steel slotted drainage grate set into grey stone-tiled floor

Wash-Down Areas and Floor Wastes

With the necessary permissions in hand, you can turn to picking which commercial floor wastes suit your wash-down space. Commercial floor wastes from our range suit either 100mm or 150mm pipe sizes, though some point drains run to a 50mm outlet instead — check each item description to confirm the pipe or outlet size before ordering.

The arrestor versions include a removable strainer basket that catches debris before the drainage line, but it's still no substitute for a grease trap. We also stock vinyl floor wastes, which come fitted with a vinyl clamp for sheet vinyl flooring jobs. Ask your designer or tiler which slip-resistant flooring finish suits a commercial wash-down area.

Your licensed plumber is the one to ask about sizes and locations that fit the kitchen's drainage needs.

Square stainless steel floor waste grate with angled slotted drainage pattern

Picking the Right Stainless Steel Floor Waste

Next up: what material should the floor waste itself be made from? Most people underestimate how much the grade matters here. Commercial kitchens deal with constant wash-down and moisture day in, day out, so a grate has to stand up to corrosion and general wear. We stock stainless steel floor wastes in both grade 304 and grade 316, with round or square grates and anti-slip designs for busier areas.

Grade 316 is more corrosion-resistant than grade 304, but neither is completely corrosion-proof, so please check the product description to confirm the grade, and remember that even with the highest-grade stainless steel, grates still need regular cleaning. You should ask your licensed plumber if the floor waste or clear out you're buying needs WaterMark certification for your specific project.

Plumber kneeling beside open floor drain in commercial kitchen, tools in hand

Keeping the Lines Accessible

A floor waste alone will not prevent issues caused by blockages elsewhere in the drainage line, and in a busy kitchen environment, that is simply a matter of when, not if. Installing clear outs gives the licensed plumber direct access to the drainage line without needing to remove the floor.

Position clear outs so they are easily accessible and not hidden behind permanent installations or bench tops. Fixing a blocked drainage line, like all commercial kitchen drainage work, is a job for licensed plumbers in all states and territories.

References

AS/NZS 3500.2:2025 Plumbing and Drainage — Sanitary Plumbing and Drainage, Standards Australia

AS 4586:2013 Slip resistance classification of new pedestrian surface materials (incorporating Amendment No. 1:2017), Standards Australia

WaterMark Certification Scheme, Australian Building Codes Board

Plumbing licensing requirements, state and territory plumbing regulators

FAQs

So how often, realistically, should clear outs and floor waste baskets get cleaned?

Most commercial kitchens pull the strainer baskets at close each night — leave food scraps sitting overnight and you'll get morning odours plus sluggish drains. Clear outs don't need opening that often, but it's better to follow a schedule your plumber sets than wait for a blockage to force the issue.

Can an existing floor waste be upgraded without retiling the whole kitchen floor?

In most cases, yes — provided the new unit matches the existing outlet size and pipe position, which your plumber can confirm on site. Swapping grade or grate style is usually straightforward; however, moving from a 50mm outlet up to 100mm or 150mm typically means floor and drainage work too.

What's the real-world difference between heel-proof grates and standard ones?

Heel-proof grates are built to lower the chance of staff catching a shoe or heel when moving quickly on wet floors; check the product description for the specific design. Ask your designer where heel-proof grates are worth the extra cost; busier walkways and pass areas are the usual spots.