Speaking to news.com.au, the Motueka resident said the tourist left the mess on the lawn.
"I chased after him … and got his number plate. I spent the whole day on Saturday hunting through freedom camping zones in the area but could not find him," he said.
"As weird as it is, I woke up [Sunday] morning and looked out my window and there he was. Parked up, freedom camping on my street directly outside my house. He then got out and started urinating on the footpath."
Grooby said he then rang a member of the council who fined the tourist $400 and made him clean up his mess.
"Our town is truly fed up [with] these dirty tourists leaving our town a mess and taking it for granted," Grooby told news.com.au.
"We have public toilets and rubbish bins everywhere in our town. And they still do this."
The Nelson-Tasman region is popular with freedom campers, and their impact on the region has been a focus for the local council which has previously sent freedom camping ambassadors to hotspots to inform visitors of their responsibilities.
A spokesperson for Tasman District Council told the Herald the incident was "disappointing" and is something they and the community won't tolerate.
"The gentleman was fined a total of $400 - $$200 for defecating in a public place and $200 for breaching freedom camping bylaw," the council said.
"This behaviour was disappointing on a number of counts including that of common decency. As a community we have invested in enough infrastructure to ensure the environment and our residents do not have to experience such actions. Regardless of the person doing it this action goes beyond what any community will tolerate."
• The Freedom Camping Act was passed in 2011, laying down laws around when and where people could camp outdoors. • The act rules anyone parking or camping in a public space overnight is bound by the same laws as occupying public land at any other time. • Local councils were given powers to restrict or prohibit freedom camping. • As well as regional restrictions, the Department of Conservation has identified more than 200 sites where camping is prohibited or restricted. • Tougher rules implemented in February 2018 set regulations around which vehicles could park in areas reserved for "self-contained" campervans. • Those changes mean only vehicles with an on-board toilet will receive the "self-contained" certificate. Toilets must be accessible and usable at all times. Portable toilets are allowed with tougher regulations. • Fines range from $200 to $10,000 — the latter for those caught dumping major waste.