A professional often begins with a CCTV drain survey to pinpoint the exact location and nature of the blockage.

Leo sat on the back step of his van, ignoring the growing puddle of grease water around his boots. He opened to a random page.

He parked the jetting van, a battered Mercedes with a 3,000 PSI pump in the back, outside “The Golden Spice.” The owner, Mr. Khan, was pacing the alley, his face the colour of old turmeric.