# Forum Home Renovation Structural Renovation  rain head, what does it do? them large boxes on down pipes.

## wozzzzza

i have seen many times on larger buildings how they have this large box with a downpipe coming off of the bottom of it, it also has an overflow hole in the top.
what is the purpose of these boxes?? is it to ram water down the pipe or something by creating increased head pressure from all the water collecting up the top in that box on a large down pour to help move the water quicker??

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## seriph1

they just store a small amount of water that collects while it is literally turning the corner between the roof and the downpipe - by doing so, I imagine it stops the water from splashing over the edge all the time during heavy downpours.

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## bricks

Rain heads by design normally have an opening in them so that if the pipe blocks the water spills out over the head. 
That and they also became quite fashionable for a while.

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## wozzzzza

so they are nothing more than a fashion statement? they serve no other purpose??

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## Ashwood

I'm not a plumber but i was told that nowadays it is a requirement to have an overflow (hole) and the "rainhead" has the hole which does that. 
I would also presume that the rainhead serves as a holding reservoir to help cope with inflows from the gutter run during heavy downpours, while the water is being drained down the downpipe.

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## RedRaven

Its just there to serve as a spill point.  If the downpipe or drain blocks up, the water would overflow the gutter itself, meaning water is going to pour into your ceiling. 
With the rainhead installed, water will overflow at the rainhead, and cascade (relatively) harmlessly down the wall, not into your plaster ceilings. 
It won't save you from overflowing gutters due to not being cleaned out once in a while.

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## bricks

> so they are nothing more than a fashion statement? they serve no other purpose??

  they are for over flow protection on your roof, like i said before???

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## SteveR

They serve four purpouses
1.  Provide increased head pressure.
2.  Increase area of rainwater capture. (longer circumfrence)
3.  Provide overflow protection.
4.  Provide some additional initial capacity for sudden downpours. 
I know this becuase I tried to delete them on the last building I worked on, and had this explained in detail by the hyd. engineer. 
Regards, 
Steve

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## Jacksin

I don't agree with all 4 of the above points so my short answer is-- to separate the downpipe from your box gutter should it ever block and cause the building to flood. 
Head pressure? I doubt it.

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