blocked drain

A drain may be blocked by (i) the build-up of silt, organic debris or grease within it, (ii) fracture and collapse due to displacement (settlement, soil compaction, sub-surface erosion, tension sling etc.), (iii) collapse due to the deterioration of the material from which the drain is made (see pitch fibre), or (iv) the ingress of roots into a leaking drain. See rodding, rooter, jetting hose.

This definition is abridged from A – Z of tree terms: A companion to British arboriculture.
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