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Slotted Drain™

Slotted Drain pipe removes sheet flow from streets, highways, and parking lots without multiple grades or water channeling devices. The result is an aesthetically pleasing inlet that is safer and easier to install and maintain.

Aesthetically Pleasing Inlet for the Removal of Surface Water

Slotted Drain™ is a unique pipe which removes sheet flow without multiple grades or water channeling devices.

The pipe is cut along a longitudinal axis, and a trapezoidal or straight-sided grate with reinforcing spacer plates is welded to form a 1 3/4 -inch-wide slot opening. The slot collects runoff and channels it to the pipe below from which it flows to the appropriate outlet.

Slotted Drain is fabricated from galvanized steel for excellent durability or from Aluminized Steel Type 2 (ALT2) when more corrosion resistance is required.

The result is a practical, aesthetically pleasing inlet for the removal of surface water on streets, highways, and parking lots. Designers and engineers installing walkways and promenades around sports stadiums, civic centers, shopping malls, parks and other pedestrian-traveled surfaces have used Slotted Drain as an integral part of the landscape architecture.

Unlike typical parking lots that require grades to be sloped in four directions for each storm collection grate, a parking lot with slotted drain requires only one transverse and one longitudinal slope for the entire drainage area. That translates to a lower-cost installation for the contractor and owner; and less stake-out for the engineer. Because of Slotted Drain’s efficiency in removing surface water, fewer collectors and fewer laterals under the roadway are needed.

On roadways and highways, replacing curbs and drain basins with continuous lengths of Slotted Drain opens up an obstruction-free and single grade roadside that greatly enhances the effectiveness of the shoulder to improve safety.

Slotted Drain Features and Benefits


Fabricated from Contech Corrugated Steel Pipe

Structurally sound, supports H-20 loading

Intercepts up to 50% more runoff than most standard 2’ x 2’ grate inlets

Improved drainage efficiency

Only one transverse and one longitudinal slope

Fewer collectors and fewer laterals, lower cost installation

Hazardous dips and ponding grades are eliminated.

Improved safety

Straight-sided grate

Fewer debris problems, lower cost maintenance

Slotted Drain Pipe Coatings

  • Galvanized Steel - Pipe made from steel coated with zinc to extend service life. The most widely used and most economical metallic coating for corrugated steel pipe
  • Aluminized Steel Type 2 (ALT2) - Pipe made from steel that has been hot-dipped in commercially pure aluminum; offers 75 years or more of maintenance free service life

Slotted Drain Pipe Properties

  • 12” – 36” diameters available in 14 and 16 gauge
  • 30” and 36” diameter available in 12 gauge

Slotted Drain Pipe Accessories

Slotted Drain Applications

  • Curb inlets
  • Inlet system across driveway cuts
  • Shoulder drains along median barriers
  • Pedestrian thoroughfares, malls and bicycle paths
  • Replacements for curbs and berms where those obstacles are undesirable for safety reasons
  • Ground-level floors with drainage requirements
  • Parking lots or other continuous paved surfaces
  • Sidelines of playing fields in stadiums
  • Airport aprons, taxiways, hangars, and deicing areas
  • Railroad intermodal facilities with heavy wheel loads

Technical information for this product is centrally located in the technical guides section.

View Technical Information
Slotted Drain for Drainage

Slotted Drain is a continuous opening inlet that efficiently removes surface water on streets and highways. The grate on a standard 20-foot length of Slotted Drain will intercept up to 50% more runoff than most standard 2’ x 2’ grate inlets. In parking lots, Slotted Drain removes sheet flow without complex multiple grades or water channeling devices like asphalt dikes, berms and curbs.

The Contech Advantage

Agency/Regulatory Guidance

Our team is ready to provide you with expert advice and assistance on local regulatory requirements, resulting in faster approvals.

Solution Development

Our engineers can review your requirements, weigh all options, and recommend the optimal solution to integrate with your site designs.

Technical Expertise

Our engineers can assist by providing product specific engineering calculations such as hydraulics, buoyancy, foundation reactions, and unit sizing.

Cost Estimates

We can quickly provide engineer’s cost
estimates to assist with your solution
selection process.

Site Specific Drawings

Our engineers can provide site-specific drawings for proposals, project meetings, and submittals, helping you be more efficient with your time.

On-site Assistance

Contractors know time is money, so we provide preconstruction meetings, delivery coordination, and on-site installation support to ensure a timely, smooth installation.