Some people living close to the two giant sheds at Cwrt Malle Farm near Carmarthen want them pulled down.
The county council is to consider a retrospective planning bid for the dairy which houses 1,800 cows.
Farmers Howell and Susan Richards defended their development on BBC One Wales' programme Welsh Mega-Dairies, which was broadcast on Thursday.
Mr and Mrs Richards rapidly expanded their business over a year ago without planning consent.
Their cows are milked 24-hours-a-day, seven days a week, and do not graze the grass surrounding the farm.
United StatesMr Richards argued it should be seen as a way to improving farming fortunes rather than turning the cows into little more than an industrial operation.
He said he was inspired by a mega-dairy he saw in the US where dairy herds numbering 30,000 were kept in sheds.
Continue reading the main storyWe are now considering their impact on the community, the local road network and the local environment”End Quote Eifion Bowen Carmarthenshire council "I learned more in a week out there than I probably learned in 10 years of farming here," he tells the programme.
But they may be forced to pull down their sheds if the planning decision does not go their way.
Carmarthenshire council's head of planning Eifion Bowen said the couple were warned they needed permission before the development was finished.
"We are now considering their impact on the community, the local road network and the local environment," he said.
Another farmer, in Welshpool, is contemplating following the Richards by increasing his own herd five-fold to 1,000, all housed in a high-tech dairy.
Fraser Jones's proposals for a three-storey milking parlour and sheds has attracted 833 comments - most in opposition.
ConcernsCritics cite concerns over an increase in lorries delivering feed and taking away milk, as well as the problems of disposing of slurry from so many cows in such a small space.
Campaign group Compassion in World Farming said there are animal welfare concerns surround mega-dairies.
Organic dairy farmer Allan Rogers says farmers can make a profit without mega-dairies Chief executive Philip Lymbury claimed cows are pushed to their physical limits to produce more milk and keeping them permanently indoors makes them more likely to suffer serious health issues.
The programme also heard from Allan and Heather Rogers, who have an organic dairy farm at Chirk near Wrexham.
They argued their commitment to producing high-quality milk, which they sell direct to the customer, is making a profit while still giving their herd the chance to graze on pasture, and also a longer life.
Their 160 cows graze on grass from March to November and in winter feed predominately on forage crops such as oats and peas which the Rogers grow on their own land.
Mr Rogers said it does away with the need to buy in expensive processed feed supplements.
"Going for low input means the cost of production is also lower so we can gain a few more pence on each litre we produce," he said.
The pair were seen together at Dudley bus station on 26 June Police have released CCTV images of a missing teenage couple from the West Midlands following an emotional appeal by their parents for their return.