Overflowing gutters in heavy rain: causes and fixes
By Charlie · Local gutter cleaner · 29 October 2026 · 3 min readGutters usually overflow because of a blockage in the gutter or downpipe. Less often, the gutter has lost its slope or is too small for the roof.
Cause 1: a blockage
Leaves, moss and silt in the gutter, or a blocked downpipe, are behind most overflows. Cleaning the gutter and flushing the downpipe usually solves it straight away.
Cause 2: the wrong fall
Gutters need a slight slope towards the downpipe. If brackets have slipped, water collects in the middle and spills over. Re-aligning brackets fixes this.
Cause 3: not enough capacity
Large roofs with a single downpipe can overwhelm a standard gutter in a downpour. An extra outlet or deeper gutter profile can help — we can advise when we visit.