Carried out drainage dye testing in Northamptonshire on behalf of a housebuilder, working alongside the local authority to verify drainage connections and establish whether any crossed connections were present. No jetting or CCTV survey was needed — a controlled dye test provided the evidence required. Uncertainty over exactly where individual drainage connections discharged, with the possibility of foul and surface water systems being crossed, meant a tracing dye was introduced at a selected drainage point and the downstream network monitored to establish where the coloured water appeared, confirming the drainage routes. No crossed connections were identified — all parties were satisfied, and no further jetting or CCTV work was required.