Panning around, she then shows the two men behind her steering.
Her video was viewed more than 1.5 million times and more than 200,000 people commented, many in favour of the advice.
"This is iconic," wrote one viewer.
Another wrote: "You know what, this is genuinely genius."
In a later video, Katie explained the story.
When asked whether the boat smelled, Katie replied: "Not at all! I think it was just sandbags and building materials."
Some travellers didn't agree, saying they'd "rather spend the €80."
But another said Venice was the perfect place to try the sneaky hack, writing: "Venice seems like the only city in the world where a tour from the bin men can be romanticised though."
In a second video, Katie said the girls took the bin men out for a drink afterwards.
"This is Alessandro and his father, they were both absolutely lovely and we went out for a few drinks with them after to say thank you," she said.
The UK traveller isn't the first to complain about Venice's steep costs.
In 2018, a party of travellers who ordered four dishes were hit with a £970 (NZ$2000) bill and subsequently called the police.
It will only get more expensive, too. Venice will introduce a new tourist fee which requires visitors to pre-book and pay a daily rate of €5 to enter through a turnstile.
Once the city reaches a certain capacity, the electric turnstiles will stop and tourists cannot enter.
