Common Causes Of Blocked External Drains
Outdoor drains are exposed to the elements every day, which makes them more vulnerable to obstructions. The most frequent causes include:
- Leaves, mud, and garden waste – Debris often builds up during autumn or after heavy rainfall, blocking gullies and drain covers.
- Fat, oil, and grease – Kitchen waste can harden in outdoor pipes, restricting water flow and trapping other materials.
- Foreign objects – Non-flushable items such as wipes or sanitary products can pass through internal plumbing and become lodged outside.
- Tree root ingress – Roots can infiltrate joints and cracks in underground pipes, gradually leading to blockages or pipe collapse.
- Collapsed or misaligned pipework – Ground movement or age-related wear can distort pipes, causing poor flow and recurring blockages.
Identifying the cause of a blockage is essential for a lasting solution. Professional CCTV drain surveys provide a clear picture of the problem before any work begins.

