They take their own cutlery, containers and water tumblers when they go out. They avoid straws, plastic bags and food packaging.
Some have a compost bin at home where they dump their kitchen scraps and use the compost to fertilise plants.
Others turn fruit peels into eco enzymes for household cleaning.
When it is that time of the month, some women use reusable menstrual cups and cloth pads instead of disposable pads.
These are just some measures adopted by members of the Facebook group, Journey to Zero Waste Life in Singapore, which seeks to reduce waste in daily lives.
With more than 900 members, it was started in May by software engineer Gan Kah Hwee, 29, who wanted to spread awareness about sustainable living in Singapore.
She had always wanted to be eco- conscious, avoiding disposables and using her tumbler and lunchbox.
However, she says: "I felt paiseh (embarrassed) about doing something different. I also didn't see others doing the same."
She changed her mind after watching the award-winning documentary Trashed (2012) by British film-maker Candida Brady in April. She says: "I realised that if we don't practise 'reduce, reuse and recycle', the trash problem is going to be serious. We have to start with ourselves and not wait for the authorities to do something."
She signed up for a sustainability mentorship programme with environmental consultancy Green Future Solutions where she met likeminded participants.
She then started the Facebook group as a form of support. "We post photos of food we buy in our reusable containers. We learn from one another which restaurants and stalls don't entertain reusables and try to avoid them," she says.
The group started with about five members, including Ms Gan's boyfriend, who runs a software firm.
Then, at a climate change seminar, she met representatives from the non-governmental agency People's Movement To Stop Haze and Singapore Youth for Climate Action and invited them to the group.
They, in turn, invited their network of environmental bodies.
The group, which has about 40 new members every week, comprises mostly people from Singapore of all ages and from all walks of life.
About 100 of them attended its first sharing session on Oct 1 at the Visual Art Studio in Boat Quay.
During the three-hour event, Malaysian environmental journalist Aurora Tin shared her experiment in leading a zero waste lifestyle.
Singaporeans Eugene Tay, from environmental group Zero Waste SG, and Farah Sanwari, from Repair Kopitiam, where people meet to repair things, also spoke about their initiatives.
Environmental educator Tan Hang Chong shared tips on how to avoid junk mail while Ms Xyn Foo, of Open Book Cafe in Bukit Pasoh Road, talked about her efforts to reduce waste at her cafe by using stainless steel straws and not offering serviettes.
Vendors also shared information about eco-friendly products such as loofah kitchen sponges, bamboo toothbrushes and reusable beeswax food wrap.
Participants also got to sample "more sustainable" coffee roasted fresh by the Really Really Fresh Coffee movement, a Kickstarter- funded project that advocates roasting coffee on demand to reduce wastage, as roasted coffee has a short shelf life.
Ms Gan hopes to organise more of such sessions. "Maybe we can visit an incineration plant and recycling facilities to see where our trash goes.
We are also thinking of organising workshops on how to make toothpaste, compost bins and eco enzymes."
Since the start of the year , Ms Aurora Tin, her husband and their dog, Lucky, have generated so little trash that their rubbish fits into a 500ml glass jar.
Ms Tin, 28, who works as a freelance environmental journalist in Petaling Jaya, Malaysia, made a resolution to live a "zero trash" lifestyle late last year.
She was in town recently to share her story with the zero waste community here.
She told the audience that in her job, she often writes about the importance of the three Rs: reduce, reuse and recycle.
But one day early last year, she found the dustbin next to her workdesk full of the empty packaging of the snacks she had eaten. "I felt like a hypocrite.
On the one hand, I was telling people to practise the three Rs, but on the other hand, I was creating so much trash myself."
In December, she found the "solution to her guilt" when she read the book No Impact Man by Colin Beavan, which chronicles how he, his wife and their daughter tried to make zero impact on the environment while living in Manhattan, New York.
She says: "I was very inspired and thought maybe I could do the same in Malaysia."
Taking a leaf out of the book of New Yorker and blogger Lauren Singer, who managed to squeeze two years of trash into a 16oz (about 473ml) mason jar, Ms Tin resolved to fit one year of her family's trash into a glass jar.
She was then renting a room in a condominium with her solar engineer husband, Mr Lau Tzeh Wei, 28, and their dog.
She tells The Sunday Times that they started preparing themselves about two weeks before the turn of 2016 to give themselves "some time to adjust, as habits cannot change overnight".
To find alternatives to plastic containers, they got family and friends to pass them empty glass jars they no longer wanted.
The couple gave away food with packaging to their friends so they would not have empty packaging to trash.
They converted their dustbin into a recycle bin.
Food waste was stored in the freezer and donated to an environmental non-governmental organisation after one to two weeks.
When they later rented a bigger space in a terrace house, they created a compost bin.
Much effort went into avoiding plastic bags and products including food, household and personal hygiene items that came with packaging which cannot be reused or recycled.
To avoid packaged products often found in supermarkets, they started buying groceries from the wet market and used a shopping bag for vegetables, tiffin carriers for wet produce such as tofu, and stainless steel containers for meat.
They stopped buying some of their favourite processed canned food such as baked beans and pasta sauce, as well as Milo packs and milk cartons.
Stores where household detergents and condiments such as soya sauce can be refilled became places they patronised.
Instead of plastic toothbrushes, they used bamboo ones, which are biodegradable.
They also made their own toothpaste from coconut oil and baking soda.
Ms Tin switched to using a menstrual cup, which is a flexible cup inserted into the vagina to collect menstrual blood.
It can be cleaned and re-used. In the last month, she stopped using shampoo.
She says: "Over time, we found there are many things we can live without.
If we really need something, we will always be able to find a substitute for it. For instance, instead of milk, we now take soy milk."
Life became simpler.
She says: "In the past, I tended to use more condiments when I cooked, but nowadays, it's just sugar, salt, soya sauce and coconut oil."
Thanks to practical tips from the book, Zero Waste Home, and the Facebook group, Zero Waste Heroes, the journey has not been too rocky, she adds.
The most challenging part was in the first few months, when she and her husband were caught out by unexpected situations.
For instance, a cup of hot Milo came back with a plastic stirrer and their checked-in luggage had a sticker plastered on it.
They have since learnt to scan restaurants before making their orders and to travel without checking in their luggage.
Her husband found it difficult at first to refuse gifts from others. Ms Tin says: "I'd get upset when he came back from events with items, such as a T-shirt in a plastic bag."
So far, however, the people around them, including Ms Tin's parents, have been supportive.
Her mother-in-law sometimes still gives her food that comes in plastic bags or apples with stickers on them.
She says with a laugh: "I would quietly forget to bring them home or reject them gently."
To date, her glass bottle is about two-thirds full and is largely filled with small plastic parts, as well as some empty medicine blister packs and used dental floss.
She believes they are on track to keep all of this year's trash inside it.
She has not decided if she will keep her trash in another jar once this one fills up. But she is sure she and her husband are not returning to their previous way of life.
They have cut their spending by 40 per cent, through eating at home more often and buying fewer things.
Ms Tin says: "We also feel healthier as we usually dine in and eat mostly vegetables and grains."
Her greatest reward? "I feel so much less guilty towards the Mother Nature I love."
Being environmentally conscious rises to a new level of difficulty when one has children.
Outreach manager Benjamin Tay, 34, who carries his own lunchbox and cutlery, uses second-hand gadgets and does not drive, found being eco-conscious easy at first. But with the arrival of his daughter, Margaret, in 2013, reducing waste became more difficult.
"Babies seem to need so many things, from diapers to milk to toys," he says.
He and his wife, Wong Lexin, 33, a housewife, try their best. Margaret, who is turning three, wears cloth diapers at home and uses disposables only when they are out.
Other than a Lego set, which Mr Tay bought because she can "play with it for a long time", her toys are mostly gifts.
Her clothes are also either gifts or hand-me- downs.
Her stroller, diaper bag and storage boxes for toys were bought from a community marketplace for buying and selling.
The children's books she reads are borrowed from the library.
She sleeps in a toddler-sized bed which was converted from her cot and can be upgraded to a single bed.
The family, who live with Mr Tay's parents, are looking to buy a three-room Housing Board flat.
Mr Tay estimates he has saved at least $1,000 by turning to reusables and pre-loved items.
While he does take Margaret to toy stores, he lets her know in advance that she can only window shop and that she has many toys at home. "So far, she has not asked us to buy toys for her," he says.
When he was a child, he read a book about the impact of human behaviour on climate change and that influenced him to buy less and waste less.
Because of him, his wife of four years also does not patronise hawker stalls that use disposables.
Mr Tay sold his car this year to reduce pollution.
And to avoid creating electrical waste, he uses a second-hand phone, iPad and a refurbished Macbook.
The haze last year and its impact on his daughter - she had throat irritation and cough - boosted his conviction as an eco warrior.
He started volunteering at People's Movement To Stop Haze.
When the environmental non-governmental organisation was officially registered as a society in June, he became its manager of people and outreach.
While he is passionate about the environment, he would not go to extremes.
"I believe in making compromises. So if the coffee shop uncle does not want to pour the cup of coffee into my tumbler, I'd either finish up the cup of coffee there or pour it into my tumbler myself. Habits take time to change and he may have his constraints."
This eco warrior started young and in small ways.
Ms Oan Jia Xuan, 18, started recycling when she was 10.
The Hwa Chong Institution student says: "I remember putting plastic bottles, paper, metal cans and glass bottles into recycling bags and encouraging my parents to do the same."
In primary school, she urged her classmates to throw plastic bottles and paper into the school's recycling bins.
To save paper during maths class in secondary school, she drew a vertical line down her foolscap so she would have two columns to write in, instead of just one. She says: "The teacher told me not to do it a couple of times, but when I continued to do so, he just left it at that."
She never wastes food and was shocked to learn that others do. She says: "When I was in secondary school, I saw two full trays of beehoon being thrown into the dustbin after a buffet in school. I was shocked to see so much food being thrown away."
During recess, she started reminding her friends to finish their food or to ask for less rice in the first place.
She recalls with a laugh: "I think some of them became afraid to eat with me."
Joining the Green Council, an environmental club at Hwa Chong Institution, boosted her commitment to the green cause.
She became familiar with the waste statistics in Singapore and overseas.
Realising how serious the situation was, she started to consume less.
"I realised that of the 3 Rs of 'reduce, reuse and recycle', Reduce is the most important. If we can reduce, then we don't even need to think about reuse or recycle."
To reduce the use of plastic bags and styrofoam boxes, she takes a tumbler and lunchbox to "tar pau" food and uses a container when she buys buns from the bakery.
She also takes a washable cloth bag instead of a plastic bag to school for putting her soiled clothing in.
Recently, she stopped consuming Yakult, a drink she loves. She explains: "Each time after drinking, you need to throw away an 80ml bottle and a straw."
She has also stopped buying sweets, chocolates and biscuits that are individually packaged. Instead, she buys them in bulk if she wants to eat them.
To save electricity, she has been using cold water to shower for the past year. She charges her phone only once in two days.
Some of her habits have rubbed off on her parents. Her father, 55, who runs his own business, and her housewife mother, 53, now use reusable containers and shopping bags.
They live in a five-room Housing Board flat.
Jia Xuan is so fired up about the cause that she has written to one shopping mall and at least two supermarkets and eight companies, including clothing and furniture shops, to get them to switch from plastics to reusables.
She plans to pursue environmental studies in university.
She says: "I hope to be involved in policy-making one day and help Singapore become a more sustainable country."
A version of this article appeared in the print edition of The Sunday Times on October 09, 2016, with the headline Eco-conscious Singaporeans' zero waste way of life. Subscribe