In the Lake District, an army of engineers with a battery of machinery are constructing one of Britain’s biggest fresh water pipelines. It's a bug's life for Steve and Anthony, as they discover a whole new colony of wildlife feasting off unmentionables.
Steve and Michael tackle a stubborn Liverpool fatberg the size of four jumbo jets, while Mick and John try to stop a sewage leak from ruining Passover.
Steve and Michael send newbie Dan to fight the fatberg. A Warrington water main has burst, flooding local roads and causing 17,000 taps to run dry. Mick and John respond to Mrs Windsor's urgent manhole problem.
There are three weeks to clean an effluent-encrusted sewer beneath a golf course - unless the rain comes. Denzil the sniffer dog detects a whiff of chlorine on the Welsh borders. A potential pollution problem must be fixed within two hours, or heavy fines will be incurred.
A fire-fighting helicopter is chartered to stop a wildfire on the West Yorkshire moorlands reaching a reservoir. Repair works force half of the north-west biggest sewage treatment works to shut down. A failed attempt by two neighbours to clear a blockage results in them losing 11 of their rodding tools down the drain.
A team of specialist divers in the Irish Sea are on an underwater mission to clean out a massive submerged outfall pipe which disperses treated waste water deep into the sea
Stuart tackles a 200-metre fatberg in Manchester, newly qualified "leak listener" Dan detects holes in the water company's network, and the Steves attract donkey attention on a flooded farm.
Teams have to do deal with the largest fatberg seen in the North West, filling 40 per cent of the main sewer system in the docks area of Liverpool.