What is a rainwater head (hopper head)?
A rainwater head, also called a hopper head, hopper or leader head, is a box in which rainwater collects briefly before running away down the downpipe. It is fixed to the facade between the roof outlet or gutter and the downpipe, and acts as a buffer and junction in the rainwater drainage system. In Dutch it is called a vergaarbak or klensbak. Not to be confused with a hopper window or a slop hopper, which are something else entirely.
What does a rainwater head do?
- Buffer in heavy rain: if the downpipe briefly cannot cope, the head takes the surplus so the water does not back up onto the roof or in the gutter. This matters most on flat roofs that drain through an outlet in the parapet.
- Joining: two neighbouring outlets can be connected to a single downpipe through one head.
- Warning: if the downpipe blocks, you want to see it before damage occurs. There are three ways to do this. With an open top, water spills over the rim (visible, but it runs down the wall). A spout is a small pipe near the top that throws the water clear of the facade. A telltale notch is a round or V-shaped cut-out near the top that lets water out before the head or gutter overflows.
| Open top | Water spills over the rim: visible, but it runs down the wall |
|---|---|
| Spout | Small pipe near the top that throws the water clear of the facade |
| Telltale notch | Round or V-shaped cut-out near the top that lets water out before the head or gutter overflows |
Materials
Rainwater heads are made of zinc, copper, aluminium and plastic. On old buildings they are often ornamental and were historically also made of lead or cast iron; on new buildings they are usually simple rectangular or funnel-shaped boxes.
Application
You see rainwater heads mainly on flat roofs that drain through the parapet, where gutters meet at one point, and on historic facades. The head must be large enough to pass the water from every connected outlet and to stay accessible for maintenance.
Tips and points of attention
- Cover against birds and leaves: fit a removable grille over an open head so birds cannot nest in it and you can still clean it.
- Never seal the spout or notch: that is the emergency overflow. Without it, you only notice a blockage when water gets indoors.
- Clean regularly: at least after leaf fall in autumn, just like the gutter.
- No zinc below copper: do not let a copper roof or gutter drain into a zinc head, because water carrying copper attacks zinc.
- Water spilling over the rim? The downpipe is probably blocked. Check the grille or leaf guard first.
Related terms
- Rainwater drainage
- Gutter
- Rainwater offset (swan neck)
- Folded zinc
- Slope
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