Charged Rainwater Collection

Thanks to SaveH2O, of Supadiverta

This diagram indicates a charged rainwater collection system. These are sometimes called either a “wet” or a “pressure” system.


Charged Rainwater Collection

NB. This diagram has been simplified for clarity.  A leaf diverter, and an adequate overflow, must also be fitted.

With this type of system a section of the pipework always remains full.

As the pipes are under pressure it is essential all the joints in above ground and underground pipework are fully watertight.



  • Allows you to discharge water at a height above the ground level at the down pipe (But not at the top of the tank – see the post: Inlet Improvements)
  • Neater than above ground pipework
  • Additional down pipes can be connected without diverting pipes along walls.



  • It is more likely to block as the flow through the pipes can be fairly slow and the low points can collect silt. (It is also more difficult to unblock.)
  • Higher cost than above ground systems due to trench excavation, and additional inspection fittings.
  • Potential for mosquito  breeding  in water unless appropriate screes are installed.
  • Harvesting additional downpipes  without adequate overflow capacity can result in the tank overtopping during heavy rain.


Also see Underground Pipes