Ms Wan Jia Ling was looking through some old photographs last year when she came across a picture of her elder son that gave her pause.

Her toddler, Shi Yihuan, had arranged about six empty diaper boxes in a row to make a "bullet train". These high-speed Shinkansen trains are an icon of Japan, where their family was living at the time.

Ms Wan and Yihuan, now 31/2 years old, had accompanied her husband, Dr Shi Chuang, 30, to Osaka, where he did his post-doctoral studies from 2014 to last year.

Looking at the photo of Yihuan grinning as he "drove" his make-believe train, Ms Wan, a 33-year-old housewife, realised that she had even more disposable-diaper boxes lying around: "I thought, 'Do I really use so many diapers?'"

Influenced by the strong culture of recycling in Japan, she resolved to reduce waste by eschewing disposable diapers in favour of washable cloth ones for her second son, Yifan, who was born six months ago.

She has cut down further on wastage by using cloth wipes instead of disposable wet wipes to clean Yifan's bottom when changing his cloth diaper.

"I have to do more washing and drying, but it's about being eco- friendly," she says.

Now an advocate of cloth diapers, she will be co-hosting The Great Cloth Diaper Change Singapore on Earth Day on Saturday. Members of the public, including those who wish to learn about cloth diapering, can take part in this event, now in its second year, at Bukit Batok Zone 2 Residents' Committee.

Parents in Singapore and in at least 18 other countries, such as Indonesia, Malaysia, the United States and Spain, will simultaneously change their babies into reusable cloth diapers at 11am that day (visit tinyurl.com/ma9ertw to register and for more information).

Besides being more environmentally friendly, advocates such as Ms Wan say the additional advantages of using cloth diapers are significantly lower costs and lower incidence of diaper rash.

Some vendors of baby products in Singapore have seen increased sales of cloth diapers, driven by environmentally conscious parents.

Ms Rita Kusumadi, the founder of Bumwear, which sells cloth diapers and other environmentally friendly baby products, says sales of cloth diapers have increased steadily since she started the brand in 2002. Sales spiked by 30 per cent between 2015 and last year, she adds, declining to give specific figures.

She attributes the rise in demand to greater awareness among Singapore parents of the green movement.

The United States-based Real Diaper Association, which advocates and supports cloth diapering, says disposable diapers make up 50 per cent of household waste in a house with a child in diapers.

Each year, billions of disposable diapers enter landfills where it takes hundreds of years for them to decompose, according to the association. It estimates that nearly 90 per cent of babies in the US and Canada use disposable diapers.

On its website, the association estimates that disposable diapers will cost about US$1,500 (S$2,000) during the first two years of a child's life. This is based on prices in San Francisco, California.

In contrast, it estimates that cloth diapering a child over two years costs about US$450.

In Singapore, the majority of parents use disposable diapers on their young children.

Church worker Lynette Lee, 36, who has three-year-old twins - a boy and a girl - and another one-year-old son, says she does not want to try using cloth diapers.

"It sounds troublesome. Feeding and cleaning babies are already intensive work. Where would we have the time to wash cloth diapers?" says Ms Lee, who employs a domestic helper.

However, Ms Abby Lye, 44, the founder of Moo Moo Kow, a home-grown brand specialising in cloth diapers and other diapering products such as cloth wipes, says she has seen greater demand for cloth diapers, in part because parents are becoming more receptive towards the "lifestyle changes" involved in caring for and washing the fabrics.

Ms Wan experienced initial hiccups while getting used to cloth diapers.

She ordered online pre-loved cloth diapers, which she discarded after they arrived because they "smelt quite bad". Laundry detergent residue on the material is one possible reason for such malodorous diapers, she adds.

She still uses disposable diapers when going out with her kids because this means having "fewer things to carry" on public transport as cloth diapers tend to be bulkier.

Also, Yifan's cloth diaper leaked one time she was out with him.

The care of cloth diapers includes emptying and rinsing them when they are soiled.

Ms Wan washes the soiled diapers and cloth wipes in the washing machine every day and dries them in the sun, which bleaches stains and removes odours.

She finds it convenient to take off a cloth diaper and place it in a diaper bag for laundering later.

"It's almost like using a disposable diaper," says Ms Wan.

Bumwear's Ms Kusumadi, who is in her 40s and has five children - aged between 10 and 20 - says reusable diapers these days are a far cry from traditional cloth diapers made of muslin, which have been used on generations of young children in Singapore.

"I tried to cloth diaper my first child, but I gave up within two weeks because maintaining the traditional muslin diapers was difficult at the time. When there was poo, you had a hard time scrubbing the diaper clean," she says.

Ms Kusumadi says she started Bumwear - originally an online business that now has two brick-and-mortar stores - because her third child had a persistent nappy rash as a baby, which cleared up only when she started using modern cloth diapers.

There are many reasons for diaper rash, including excessive moisture on the skin, skin sensitivity, chafing or chemical irritation.

These days, cloth diapers come in a range of designs, typically including inserts or layers, which are usually made of absorbent materials such as cotton or microfiber. Additional inserts can be used at bedtime to avoid overnight leaks.

The cloth diapers can also have waterproof exteriors that look like pants. Some reusable diapers are adjustable in size and can be used from the newborn stage until the toddler is potty-trained, usually around the age of three.

Washable diapers and disposable diapers come in a broad range of prices. Cheaper cloth diapers can cost around $8 each, while high- end ones cost more than $40.

In comparison, a 42-piece pack of a popular supermarket chain's house brand of disposable diapers for newborns costs about $12 - working out to be about 30 cents a diaper - while more expensive brands can cost about 40 cents a piece.

Housewife Irma Niza Jamal, 33, uses cloth diapers mostly because of the cost savings.

"Besides environmental concerns about landfills, using cloth diapers saves a lot of money, especially if you have the ones which can take the baby from a newborn to about three years old," she says.

She estimates that she has invested about $450 on close to 30 cloth diapers for her daughter, Eesha Naira Mohammad Khirruddin, who is now 17 months old.

However, this is nothing compared to the $500 she estimates she has spent on disposable diapers in her daughter's first few months, though newborns tend to use more diapers than older babies.

She used disposable diapers on her daughter for five months after birth partly because she wanted to get used to caring for and breastfeeding her newborn.

Now, she uses cloth diapers for Eesha even when they go out, securing poo-stained diapers in a bag until they are taken home to be laundered.

Ms Irma's household is eco- friendly. The family members do not use tissue paper or kitchen towels, preferring to use cloth rags instead.

The only downside to using cloth diapers, Ms Irma reckons, is "the difficulty of finding a babysitter, as not many accept cloth diapers".

She eventually found a childcare provider who is willing to use cloth diapers on her daughter as Ms Irma, a former customer service professional and certified make-up artist, is planning to return to work in July.

She and her 35-year-old husband, Mr Mohammad Khirruddin Ismail, a ticketing executive in the tourism industry, agree that attractive cloth-diaper designs, which can include cartoon and Harry Potter characters, are part of the draw.

Mr Khirruddin says: "At first, I didn't agree because of the initial cost of the cloth diapers, but I slowly accepted the idea. Also, the designs are nice."