How long does it take you to fill up a bin bag? For Lauren Singer, the answer to that question would be counted in decades.

Singer, 25, can fit her last four years' worth of rubbish into a glass mason jar. Interviewing her on a warm London day, with my plastic cup of water drawn from a plastic water cooler, I feel slightly inadequate.

As a former sustainability manager for the New York City Department of Environmental Protection, you may think Singer has a vested interest in promoting a zero-waste lifestyle. But she wasn't always this eco-conscious.

The lifestyle change started in 2012, when she was reading environmental studies at New York University, which led to her becoming an active campaigner on environmental issues.

The real "aha moment" came in her final year. "There was a girl in my class who every day would bring this big plastic bag with a plastic container of food, a plastic fork and knife and a plastic beaker and she would eat everything, then throw it all in the trash. And I remember thinking this is super weird because we're sitting in this class learning how to make the world a more sustainable place for humans and here she was making all of this trash. There was this disconnect.

"Then one day after class I went home and opened up my refrigerator and I saw that every single thing I had in there was packaged in plastic. I felt like such a hypocrite. One, because I had been bad-mouthing this girl in my head and, two, because I was protesting against the oil and gas industry - whose biggest by-product is plastic - and through my consumption habits I was actively supporting them on a day-to-day basis."

But there's more to living sustainably than cutting down on plastic. Singer makes her own, well, everything. Toothpaste, make-up, deodorant, body lotion, laundry detergent. She buys only second-hand clothes and eats a largely vegan diet.

The upside of this (other than saving the planet of course) is that it's a much cheaper way of living.

And it also led to the inception of her company, The Simply Co.

"I found that, in the US, companies aren't required to disclose the ingredients on their packaging. As consumers, we have a right to know what's in our products." So she set up a company selling her organic, vegan laundry detergent. This was about a year-and-a-half ago after a successful Kickstarter campaign to get it up and running, and "demand for The Simply Co grows every day".

Singer has big plans for the future. Currently, she sells her product online and in select stores in (sustainable) glass jars but ideally would like to remove packaging from her business model. "Ultimately, my goal for the company is to sell package-free, to sell everything in bulk so people can bring in their own containers and refill them. I believe that the best packaging is no packaging. I want to show people that single-use packaging is a terrible use of resources and it costs people money that they shouldn't be wasting."

As part of her desire for "people to have the choice not to expose themselves to dangerous chemicals", Singer also hopes to take her company global. "It's not feasible until we change our packaging, [which I] see happening in the next year or so - that's something I'm most excited about."

Aside from her enthusiasm, Singer really is the poster child for the zero waste lifestyle. She's gorgeous - with her shiny, bouncy hair and gleaming smile. Not the stereotypical slightly grubby hippy that springs to my mind when I imagine a person who eschews conventional cleaning products. Nor is she a New York Jewish Princess.

"I don't like to play into stereotypes," she tells me when I ask her how her eco-lifestyle interacts with her Jewish identity. "People that are Jewish come in all different forms."

Singer's Judaism is closely linked to her family. She says religion doesn't play an active role in her life although she was batmitzvahed "in a Conservative temple in New York", can read Hebrew and "celebrate[s] the holidays with my family."

The aspect of Judaism that really had an impact on her however is "the heritage of Judaism - what my family had to endure to build a life for my father and eventually for me; in that regard I will always be connected to the Jewish faith."

Her father's family travelled from Budapest to America during the Second World War and built a life from scratch.

She credits her paternal grandfather with being her inspiration when setting up The Simply Co.

"I used him as an example of how to start something from nothing. He came here without even knowing any English and kind of built this empire for himself. When I'm stressed, I think of what he did and how much he had to overcome and think that my problems are so small compared to what he had to go through."

Talking of her family, Singer says her parents and three siblings have been "amazing" in the face of her transformation.

 "My family has been really motivating and supportive of what I've done."

Although at first her father "wasn't thrilled" when she quit her secure government job to start a laundry detergent company, he has started buying organic food and using reusable bags. He jokes that "he used to have three bags of garbage and one bag of recycling and now he has three bags of recycling and one bag of garbage."

So Singer is making an impact on the world with her zero waste lifestyle. But, four years later, what does she do if she - accidentally - produces waste?

"Put it the jar". It's usually plastic tags or labels. And does she anticipate needing a new jar? "No".

trashisfortossers.com, thesimplyco.com