Selecting a Car Wash Drainage System

Choosing a car wash drainage system should be top of mind as a significant amount of water runs through the shop every day. A well-designed system can save money and time. More importantly, it keeps your customers and staff safe.

Many shops are built with a trench/grated linear drainage system. Trench grates have a tendency to bend or even break and you have to replace them eventually. The problem with many systems is they can corrode/break down, smell, and generally have poor performance handling car wash chemicals. Grates need to be replaced, are difficult to remove, clean and can be expensive.

Safety is often an issue in a car wash. The fact is your car-wash staff and customers often walk around the vehicle. Safety is always a consideration before you build your drainage system in the shop.


Properties to Consider

  • Flow Rates

Depending on the traffic your car wash needs to handle, the average flow rate of a professional car wash needs to be minimum 3GPM (gallons per minute).

  • Easy to Clean

Grates trap mud and other sediment, which is difficult to clean as grates need to be pulled out and cleaned. Having a system that minimizes maintenance, labor will have a big impact on your bottom line.

  • Safe to Walk On

To make sure the drainage system is safe for your staff and customers to walk on, it is necessary to follow certain guidelines.

  • Material Selection and Guidelines
  • Cleaning Chemicals

Some cities have regulations and guidelines in terms of using cleaning chemicals. It is suggested to use pH of 6.0 to 10.5 to minimize dissolving metals, which should be taken into consideration when you choose the material for your drain channel.

  • Local bylaws may stipulate a list of substances that may not be introduced into the storm water system. For example, soap, odorous materials, greases and waste are a few to consider under most Car Washing Regulations.

Why Use Slot Drain in Your Automotive Facility?

Slot Drain is the most durable drainage system available. The only parts of the drain exposed are the surface angles, which are made of stainless steel. The rest of the drain is embedded into the concrete and can handle weight beyond Load Class F (heavy duty such as airports).

Due to Slot Drain’s precise slope, smooth interior and the addition of flush valves, it is self-cleaning and maintenance free. This system eliminates grates that are difficult to remove, clean out, and difficult to replace.

Flush valves can be added to the drain ends, with time control in order to automatically flush the system when needed. Most car washes opt for the flush valves, then hook them up to a timer and a sump pump located in the pit. That way, Slot Drain continually flushes itself, reusing/recycling its own water.

  • Flow Rates up to 33 GPM.
  • No grating to work around / clean out
  • Corrosion Resistant
  • Slot Drain has been installed successfully In Hundreds of Car Washes, Shops, Parkades, showrooms, and Production
  • Easy to Install, Minimizing Labor/Cost. Our systems fit both new construction and retrofit.
  • Sanitary with minimum maintenance.


Case Study – Co-op Car Washes

Slot Drain is widely used in Co-op Car Washes in North America as it satisfies clients with a safe, durable and easy-cleaning system. Co-op was looking for excellent flow rates and it is corrosion resistant to the car wash chemicals. The drain channel can be cleaned with flush valves automatically, saving labor and money. The maintenance of slot drain is much lower than grated trench drains.


Slot Drain Systems are installed in hundreds of automotive facilities. Our clients include Walmart Service Centers, Federated Co-op Gas Stations & Car Washes, Esso Service Stations & Car Washes, and many chain and independent automotive dealerships and service stations.

Select Your Slot Drain

Slot Openings – 1” is standard, 1 ¼ “is recommended for heavy flow rates.

Drain Channel Material – Galvanized is the most cost effective drainage system.

Catch Basin & Basket – A Stainless Steel Catch Basin is suggested to catch solid materials or sediment before entering the storm drainage system.

Flush Valve and Cleaning Paddle – Accessories that help you clean the drain channel easily

Grates? Never need to think about them!

Our professional staff are available to provide suggested layouts as well as specification guidelines for tender purposes. Shop drawings are available upon receipt of purchase orders.