Surface Water Drainage

Drainage Central Surface Water offering includes an extensive choice of Solid, Perforated and Twinwall Pipe and Fittings in a range of diameters from 110mm - 600mm. These systems are known for ease of installation, long term reliability and guaranteed performance.

How Do I Get Rid of Surface Water?

To help disperse surface water faster, a good drainage technique is to install a French Drain. Follow these steps for what you need and we’ll guide you through the steps of how to do it too.

What do I need to make a French Drain?

  • Perforated Pipe – We recommend rigid PVC 110mm or 4 inch half perforated pipe. Using this size means you can connect in with the most readily available bends and branches of the same size system. Another benefit of using this rather than the alternative corrugated pipework, is that its smooth inner wall allows for a quicker flow of the water, and doesn’t collect any silt that were to get into the system, like the corrugated would do. Finally, because corrugated pipe is normally in a coil, once laid it curls back to its original state, also resulting in not such a smooth run, as compared to a straight length of 110mm pipe.
  • Permeable membrane – Also known as geotextile which can be woven/non-woven. This allows water to pass through whilst preventing soil or silt from blocking the pipe
  • Pea shingle – Available from all goods builder’s merchants
  • An end point for the water to go – An existing natural ditch or drainage system or a soakaway using soakaway crates. These create an area for the water to sit temporarily and eventually soak into the soil naturally. These should also be wrapped in membrane; the amount of crates you need is normally determined by your roof area – multiply length by width for roof area in metres squared.

How do I make a French Drain? (read all steps first before you begin)

  1. Dig your trench – 8 to 12 inches wide allows for more gravel to be used, which helps prevent blockages and ingress of soil. Having a wider trench also gives a greater capacity for more water to be collected and channelled away, and finally gives you more room to work and ensure there is a grade for the water to flow downwards to its end point.
  2. Line trench with permeable membrane – prevents your pipe from clogging up with silt and becoming useless. Ensure you have enough to go around the top and sides of the trench and that there are no gaps. Some people use staples, others tape to keep it altogether. An alternative to lining the trench is wrapping the pipe directly, missing this step may cut cost but can add life to drainage system by a substantial amount.
  3. Surround with pea shingle – Adding a layer of shingle or clean gravel provides water a better chance to soak downwards than thicker mud or clay which is more compact. Older trenches were solely this, a layer of gravel that acts as a channel for water to soak into. Generally, it is accepted that around 2 inches of gravel surrounding the pipe is a sufficient amount.
  4. Lay the pipe – 110mm or 4-inch diameter pipe should be laid with holes facing downwards. Remember to lay the pipe with holes facing DOWNWARDS, once the water soaks below it will find its way into the perforations, flow through the channel and away. From experience, rigid PVC pipe, rather than corrugated pipe is more effective and easier to work with for a number of reasons. Its smooth inner wall allows for quicker flow of water, rather than the ridges found in corrugated pipe that could pick up sediment. It is also easier to keep the channel straight because of its rigid nature, compared to the corrugated pipework which, because it is coiled, will twist and turn back to its original shape. Finally, if an access point is created, it is easier to clean.
  5. Repeat steps 3 and 2 – surround the pipework with pea shingle or clean gravel and cover with geotextile.
  6. Quick test – Before you cover your trench, if you want to test your new drainage system works, simply take a garden hose and press down to an area where you trench is located. If successful, the water will be exiting at the end of the pipework.
  7. Backfill with top soil – cover your new trench with a layer of top soil and enjoy the benefits of your new drainage system.
  8. What do I do with septic tank effluent?
  9. Before septic tanks are installed, building regulations and council building authorities should be consulted to ensure satisfactory and legal installation
  10. The most popular method of effluent soakaway is to install pipework in a herringbone fashion.
  11. Herringbone shape traditionally used to allow for full range of land to be used and water to soak away easier/quicker.
  12. Pipes can be used as a channel with pipes facing downwards (after a certain amount of distance) for water to soak-away into the ground naturally.
  13. Rigid PVC pipe better than corrugated because can be attached to normal 110mm fittings and access/cleaning is easier with use of access points, chambers or sampling chambers.

If you have any further questions please don’t hesitate to contact us.