Selecting the correct commercial washing machine drain trough sizing is critical for preventing facility flooding and ensuring plumbing code compliance. While standard dimensions exist, most commercial laundry facilities require specific volume calculations to handle the surge discharge of modern high-extract washers.

Commercial Drain Trough Dimensions

Here’s a baseline for matching trough dimensions to common washer capacities. Keep in mind that requirements may vary based on your facility’s specific plumbing layout. For instance, trough length typically increases by about one foot for every 30 pounds of additional washer capacity.

If your washer capacity is:

• 70 pounds, the recommended trough dimensions are 3′ x 16″ x 12″.
• 120 pounds, the recommended trough dimensions are 4′ x 18″ x 12″.
• 200 pounds, the recommended trough dimensions are 7′ x 18″ x 12″.
• 400 pounds, the recommended trough dimensions are 14′ x 18″ x 12″.

Factors Influencing Drain Trough Sizing

You can calculate volume management to prevent overflow when finding the correct size for a trough.

• Surge volume: Modern high-G-force washers release water rapidly. For example, a 165-pound commercial washer can discharge water at rates exceeding 150 gallons per minute (GPM). Standard 3-inch or 4-inch floor drains cannot accept this volume fast enough. The trough serves as a reservoir, holding the surge and allowing it to drain at a controlled rate.
• Pipe diameter: If your facility uses smaller drain piping, the trough must be sized with greater depth or width to compensate for the slower drainage speed. 
• Code compliance: According to IPC Section 802, commercial laundry equipment must discharge through an indirect waste connection to prevent sewage backflow. This requires an air gap, typically twice the diameter of the effective opening, between the discharge pipe and trough. The trough must be able to accommodate this vertical distance while containing splash-back.

Drain Trough Sizing Factors: Why Custom Is Better

While standard sizes work for new construction, retrofitting a laundry room often requires a custom approach to ensure long-term performance:

• Irregular layouts: Basements and back-of-house areas often feature structural columns or tight corners that standard rectangular metal troughs cannot navigate. Custom fabrication allows for unique shapes that maximize floor space.
• Material longevity: Stainless steel troughs often corrode at the welds when exposed to harsh laundry chemicals. In contrast, chemically welded polypropylene offers excellent resistance to bleach and alkalis, ensuring the trough maintains its integrity over decades of use. 
• System integration: Custom sizing allows you to align outlets perfectly with existing floor drains without expensive concrete trenching. 

Get a Custom Quote for Your Facility

Get a guaranteed fit for your specific equipment. H-M Company can calculate the exact surge volume capacity required for your washers and fabricate a solution that fits your floor plan perfectly. Contact us today to discuss your project or request a custom quote.