Stormwater - 90mm v 65mm

[gsouth]

Hi all,
I am putting in a sump to trap some rainwater runoff from a new paved area.
I'll be connecting it into an existing 90mm line that runs to the street, however to help me get fall I was looking ar running 65mm pipe. From near the top of the pit to the bottom of the 90mm existing line.

I know that 65mm will move less water than 90mm however I am trying to figure out if 65mm will suffice.

Cheers
Geoff

[peter_sm]

65mm will move half as much water as 90mm. You decide if that is enough size

[Big Shed]

Didn't know they made 65mm SW pipe, was under the impression 75 and 90mm were standard?

[gsouth]

sorry - you are correct I meant to say 75mm

[dazzler]

yeah, you decide and stop buggin us

[peter_sm]

75mm will be heaps, unless you are looking at runoff from over 200 square metres

[dazzler]

Can you put 2 x 75mm ones side by side to get the flow