Gravel-less pipe systems distribute treated wastewater into the soil. They are like conventional gravel-filled drainfield systems, except that gravel-less pipes are surrounded by geotextile fabric instead of gravel.
A gravel-less pipe system includes:
• A treatment device, generally a septic tank, but it can be an advanced pretreatment system.
• Gravel-less pipe, which is made of corrugated, perforated polyethylene and is commercially available in 8 and 10 inch diameters. The pipe is wrapped with geotextile fabric.
• Pipe trenches, which are 2 feet wide and no more than 150 feet long.
In a gravel-less pipe system, wastewater flows from a home into a treatment device, where settleable and floatable solids are removed. From there the wastewater moves into a drain field through gravel-less pipes.
The wastewater is stored inside the pipes until it exits through two rows of holes along the pipe bottom. It moves through the geotextile fabric and enters the soil, where microorganisms consume the rest of the wastes in the water.
Gravel-Less Pipe (and in Spanish)