Not all water arrives on the surface. Groundwater, a perched water table and slow-draining clay soils cause damp basements, failed road subgrades, waterlogged sports pitches and lost harvests. Drainage pipes with perforations collect this subsurface water and carry it away. GON works with melioration and agriculture as well as construction, so this guide covers both: drainage for buildings and roads, and drainage for land and fields.
What a land-drainage system consists of
- Perforated pipe – collects water through slots in the wall.
- Filter – a geotextile sock and/or a graded gravel envelope that lets water in and keeps soil out.
- Fall – a continuous slope to an outlet.
- Inspection points – risers or chambers for flushing.
- Outlet – a storm collector, ditch, soakaway or pump sump.
Types of drainage pipe
| Type | Description | Best for |
|---|---|---|
| Single-wall corrugated PE/PVC, slotted | Flexible coils, easy to lay | Agriculture, gardens, sports fields |
| Corrugated pipe with geotextile wrap | Factory-wrapped filter sock | Silty and fine soils, foundations |
| Double-wall HDPE, perforated (SN4/SN8) | Smooth inside, stiff | Road subgrades, deep drains, under traffic |
| Partially perforated (slots on top 2/3 only) | Collects water and also carries it along the invert | Road edge drains, long runs |
Typical applications and design notes
Building foundations (perimeter drainage) Lay the pipe beside the footing, below the slab level, with a 0.5–1% fall. Surround it with washed gravel and wrap everything in geotextile. Bring the pipe to inspection risers at the corners. Never connect roof downpipes to the perimeter drain.
Roads and highways Edge drains under the shoulder keep the pavement base dry. A dry base means fewer potholes. Use stiffer double-wall perforated pipe that can take compaction and traffic.
Sports fields and parks A herringbone layout of lateral drains feeding a collector, at spacings set by soil permeability.
Agricultural melioration Subsurface lateral drains, typically at 0.8–1.5 m depth, discharge into open or piped collectors. Coiled corrugated pipe with a filter wrap keeps installation fast over long lengths.
Installation checklist
- [ ] Continuous fall, with no dips where silt can settle (check with a laser).
- [ ] Geotextile wrap or gravel envelope suited to the soil grading.
- [ ] Minimum 150 mm gravel around the pipe on all sides.
- [ ] Rodding or inspection points at bends and every 30–50 m.
- [ ] Free-flowing outlet above the receiving water level, protected with a grille.
What to write in the BOQ
*"Perforated corrugated HDPE drainage pipe DN 160, slotted, factory-wrapped in non-woven geotextile, laid at minimum 0.5% fall in 20/40 mm washed-gravel envelope (min. 150 mm surround) wrapped in 200 g/m² geotextile; inspection risers DN 315 at all bends and max. 40 m centres; outlet to storm manhole."*
Quick selector
- Basement in clay soil → wrapped perforated pipe DN 110–160, gravel, geotextile, risers.
- Road edge drain → double-wall perforated SN8, DN 160–200.
- Vineyard or orchard waterlogging → coiled drainage pipe DN 65–110 with filter wrap, laterals into a collector.
Why source from GON
GON supplies drainage systems and drainage pipes alongside HDPE corrugated pipes, manholes and fittings, so the subsurface drains, collectors and chambers come from one supplier for construction and melioration projects alike.
Related products: Drainage & stormwater · HDPE corrugated pipe · Fittings · Manholes & covers
Further reading: Corrugated HDPE: SN 4, SN 8 or SN 12?
Is a geotextile sock always needed?
In fine sands and silts, yes. In clean gravels a gravel envelope may be enough. Ask your designer.
Which way should the slots face?
For fully perforated pipe, it doesn't matter. For partially perforated pipe, put the unslotted invert at the bottom.
Get a project quote
Send drainage layouts or quantities to sales@gon.ge or call +995 595 818 800.
GON supplies drainage, water, gas and road-infrastructure products to contractors, utilities and IFI-funded programmes across Georgia.