Blocked drains aren't always caused by silt or fat and sewage. Often it is household items such as toothbrushes, childs toys or jewellery however the number one cause we come across is wet wipes despite the fact they may flushable on the packet.
If the drain in question serves your property exclusively and it falls within your property boundary, then it is your responsibility as a homeowner to unblock any blocked drains around your property. If the drain is shared or beyond your property boundary then it's likely to be the responsibilty of your local water authority.
All of our vans are equiped with High Pressure Jetting equipment which make light work of most blockages