Conventional Drainage

The vast majority of new houses will have a conventional (sometimes called a Gravity, or Open system) storm water drainage system discharging to either:

    • Public Surface Water Drain – Typically in Eastern States
    • Soakwells on Sandy Sites – Mainly in WA


With a conventional system like this the pipes are either vertical or at a slope towards the discharge point.

A feature of this system is that when there is no flow all the pipes are empty.


  • Simple and inexpensive to design and construct.
  • If well designed, and constructed,  the speed of flow in the pipes will prevents silting and subsequent blockage.


  • This type of system can look very untidy when taking water to a Rainwater Tank that is some way from many of the downspouts (It results in lengths of pipes suspended in mid air)
  • Difficult to transfer water to a discharge point that is above the ground level of the building, although below the gutter level. A problem often encountered on demolition and rebuild projects and battleaxe blocks.

If you are planning a rainwater tank or are having problems with getting storm water to a suitable discharge point you could consider a Closed System


Also see Underground Pipes