[[File:Routing.png|thumb|Conceptual diagram of the excess routing alternatives: On the left, excess flow leaves the cell via an overflow; on the right, excess flow is diverted so that only the design volume enters the cell.]]
*Infiltration facilities can be designed to be inline or offline from the drainage system. See [[Inlets]]
*Inline facilities accept all of the flow from a drainage area and convey larger event flows through an overflow outlet. The overflow must be sized to safely convey larger storm events out of the facility.
*The overflow must be situated at the far end of the facility to prevent any localised ponding to cause bypassing of the infiltration facility.
*Offline facilities use flow splitters or bypass channels that only allow the required water quality storage volume to enter the facility.
:Higher flows are diverted and do not enter the infiltration practice. A pipe can by used for this, but a weir or [[curb cuts|curb cut]] minimizes clogging and reduces the maintenance frequency.
Metal grates are recommended (over plastic) in all situations.
[[Catch basin ]]