Because for him the answer was already, well, right on our doorsteps.
Mr Mellin and a group of friends from Colne, Lancashire, set up the Modern Milkman, which offers fresh groceries such as milk, juice, eggs and more in plastic-free packaging and glass bottles that can be returned.
Customers can use its website or app for regular doorstep deliveries with cashless ordering and no long-term commitments.
The company's growth has resulted in a revenue increase of 1,000 per cent in 2020 alone, it reports. But it started with one round and a few hundred customers - it now has more than 400 rounds and has more than 100,000 customers, says Mr Mellin.
Leeds was the first big city it moved into, he says, while Manchester and London have followed as people in both "terraced houses and gated mansions" across the country have started ordering.
But it was David Attenborough's BBC show The Blue Planet II that first got Mr Mellin and friends Becky Hilton and Tom Shaw thinking.
Co-founder and CEO Mr Mellin, 35, said: "So we watched David Attenborough in 2018. The Blue Planet baby whale - everyone's seen it, all about plastic in the ocean [the scene involves a pilot whale cradling her deceased young which may have died after being poisoned by her milk, a possible result of plastics or industrial pollution in the ocean].
"And we don't come from a food farming background, [but] predominantly myself, my grandad was a farmer and my dad was a butcher and I grew up in the industry. And it really resonated with us because we had all the skills that were really relevant to be able to fix a problem.
"At the same time we recognised what was a traditional milk round, and thought, isn't this mental how this business from the 1960s that fixes all these problems, the consumers have just completely left it behind and completely forgotten about it? So we went and bought a milk round, went round delivering milk, and then through doing that process we sort of learned why consumers had left it behind. And I think it was an industry that just never modernised, you know. People need flexibility and cash is slowly dying away, we pay more with cards and online than ever.
"So we built some technology to facilitate that and then launched that. And what the technology also allowed us to do was deepen the product portfolio. So using what is the iconic milk bottle, but then how can we do that with more things? How can we pack more things into retainable packaging, especially from a fresh food perspective? And so the business is all centred around waste reduction."
Mr Mellin laughs as he describes it as "commoditizing laziness, in the best possible way" where some delivery companies do it negatively.
"I think what we're trying to achieve with Modern Milkman is giving the customer that convenience - because we need convenience - but doing it in a way that doesn't kill everything on the way to doing that."
The company estimates that it has "saved" upwards of 53,000 wheeled bins of plastic from landfill.
In June this year the company announced that it has gained funding led by global venture capital and private equity firm Insight Partners, an investment that it hopes will create 1,000 new jobs and help the Modern Milkman to save a projected 282 million plastic bottles from landfill within the next four years.
Coming up with innovative ways to not use plastic is difficult and expensive, says Mellin. Because it is cheap, pliable and increases food shelf life by preventing micro-bacterial growth, plastic is an "amazing" material, he says.
"So everything it's amazing for are also its biggest negative. Because that's what stops it decomposing, that's what means it's around forever and can't be recycled."
The funding will partly enable The Modern Milkman to develop more ways to put fresh groceries in reusable packaging.
"One of the things that we wanted to achieve when we set out, what we quickly recognised is you're not going to fix the problem by only 10 per cent of the population...if we want to significantly reduce plastic waste and food waste, we've got to be accessible to the masses."