Subsurface drainage is an essential technique for urban and agricultural development. Clay drainage tiles were the standard type drainage pipes for centuries until the advent of plastic. Clay tiles never disappeared, and they're often the best choice for modern drainage systems. Size is one factor that affects the pipe’s function. It's a key concern for designing drainage systems, along with choosing the pipe material.
Clay Drain Tile
Clay drain tiles dominated subsurface drainage systems until plastic, polyethylene or polyvinyl chloride, perforated pipe came on the market in the 1970s. Perforated pipes have small openings that let water enter and exit slowly to infiltrate into the ground. Clay drainage tiles used for the same function are manufactured in short sections, usually about 2 feet long, and laid with one quarter to one-half inch spacing between them so water enters the pipe.
Size of Clay Drainage Tiles
The typical clay drain tile has an interior diameter of 3 1/2 inches, but they're also readily available in 4- and 6-inch diameter sizes. Drainage pipes are sized according to the extent of the area being drained. For agricultural applications, clay tiles from 6 to 24 inches were installed as main lines. For most drainage work, the larger diameter is used where the loads are higher than normal, or where the drainage system is connected to a network of pipes.
Advantages of Clay Drainage Tiles
For drain pipes to work, water must move through pipes at a velocity that keeps them flushed of sediment and debris. This is referred to as self-cleaning. The recommended minimum pipe size for drainage pipes is 4 inches, but small pipes need greater velocity to stay clear of blockages. Periodic cleaning to unclog pipes is often necessary with either a sewer snake or high-pressure water spray. Clay tiles withstand jetting pressures up to 7,500 per square inch.
Clay Tiles and Plastic Pipes
Clay tiles are connected to plastic pipes with adapters when repairs or extensions to older systems are necessary. The adapters bridge slight differences in the pipes’ diameter. Clay tiles have advantages over plastic pipes for many applications, such as durability and less reliance on granular bedding material. The simplest approach for ease of construction is matching the type of pipe when renovating an existing system, instead of introducing different materials.