What Food Scraps and Materials Can Be Composted in a Small Singapore Home

The single thing that determines what can be composted in a Singapore HDB flat is not the carbon-to-nitrogen ratio. It is whether the material attracts cockroaches, rats, or fruit flies before it breaks down. In a tropical high-rise home, the distinction that matters is pest risk. Cooked food, meat, dairy, and oily scraps are the primary pest attractants. Exclude them from any open composting system inside your flat. Singapore's municipal pest-management guidance treats these materials as high-risk for infestation. The list below is organised by pest risk, not by what is technically biodegradable.

Fruit, Vegetables, And Coffee Grounds

Fruit and vegetable scraps are the foundation of small-space composting in Singapore. Apple cores, banana peels, lettuce leaves, carrot tops, and mango skins break down fast enough that they attract pests only if left uncovered or if the bin is poorly balanced. Coffee grounds and filters add nitrogen and structure. They are low-odour and rarely draw insects on their own.

Eggshells, Citrus, And Onion Scraps

Eggshells, rinsed and crushed, contribute calcium carbonates. They do not attract cockroaches. Citrus peel and onion scraps are a common worry: citrus d-limonene repels some insects, and the strong volatiles of onion do not signal food to rodents the way cooked oil does. Both can go in. Shred them first so they break down within a week rather than sitting intact and fermenting. A 4:1 ratio of browns to greens by volume keeps the pile aerobic and odour-free.

Coconut coir is the best brown for a Singapore flat. It holds moisture, adds bulk, and has no food smell. Shredded paper bedding from an office shredder works as well, provided the paper is not glossy or heavily inked. Avoid shredded cardboard printed with plastic lamination; the film does not break down and traps moisture.

A layer of browns on top of every fresh food addition seals in odours and prevents fruit fly access. Without this layer, a bin of wet fruit scraps in a 30°C kitchen becomes anaerobic within 12 hours, producing the sour smell that signals cockroach attractant conditions. Keep the lid sealed. Drill only 2-millimetre ventilation holes to keep ants out.

Material	Pest Risk Level	Notes For HDB Use
Fruit and vegetable scraps	Low to moderate	Bury under browns; avoid large pieces of durian or pineapple skin
Coffee grounds and filters	Low	Add directly; no pre-processing needed
Eggshells	Low	Rinse and crush; dry before adding
Citrus peel	Low	Shred into strips; deters some insects
Onion scraps	Low to moderate	Shred finely; strong odour dissipates within days
Cooked food waste	High	Do not use in open composting; use bokashi only
Meat and dairy	High	Do not use; attracts rodents within hours
Oily food waste	High	Do not use; creates anaerobic, odorous conditions
Bokashi pre-processed food waste	Moderate	Requires a sealed bucket; bury in soil after fermentation

For a 10-litre bucket in an HDB flat, add two parts coconut coir or shredded paper for every one part of kitchen scraps by volume. Mix the new scraps into the centre of the pile, not on top.

A pile that smells like ammonia is too wet or has too much green; add more shredded paper. A pile that smells like vinegar is anaerobic and needs aeration. Stir it every two days. If fruit flies appear, the surface is exposed. Cover every addition with a 3-centimetre layer of browns and the flies will have no access. If cockroaches appear, the bin is not sealed or a high-risk material like leftover noodles or oily rice has been added. Remove that material immediately. Do not try to break it down aerobically indoors.

Cooked Food, Meat, And Dairy

Cooked food waste belongs in the general waste chute, not your bin. In a tropical HDB flat, leftover rice, noodles, vegetable stir-fries, and fried foods create a cockroach attractant within hours. Meat and dairy exclusion is absolute: no chicken bones, no cheese, no milk, no fish skins. These materials go rancid at room temperature faster than any bin can process them aerobically, and they draw rats through the ventilation holes.

Oily Waste And The Bokashi Alternative

Oily food waste from frying greases the pile, blocks airflow, and produces the anaerobic odour that signals failure. If you want to process these, use bokashi pre-processing: a sealed bucket with inoculated bran that pickles the food waste. Bokashi is a different method. It is lacto-fermentation, not composting, and the pre-processed waste must be buried in soil or added to an outdoor pile, not left in the bin.

The Legal Position

Singapore's food waste segregation mandate under the Resource Sustainability Act applies to commercial premises generating more than 10 tonnes per year, not to households. There is no legal obligation to separate these materials at home. The choice is practical: pest prevention.

Stopping Fruit Flies Before They Start

Fruit fly infestation is the most common failure in Singapore home composting. The cause is almost always exposed fruit scraps. A single banana peel left on the surface of a 5-litre bin can produce a visible fly population in three days. Chop scraps into pieces no larger than 5 centimetres and cover them immediately with browns. Freeze fruit scraps overnight before adding them; the cold kills fly eggs and softens the material for faster breakdown.

Bin Design That Keeps Rodents Out

Rodent prevention depends on the bin design. A bucket with a locking lid and no gaps larger than 2 millimetres will keep out rats. Do not use a wooden bin indoors. Moisture seeps through joints and the odour attracts rodents through the walls. Plastic buckets with a rubber gasket seal are the standard in Singapore for a reason. If you hear scratching at night, remove the bin's contents into a sealed bag and take it to a community drop-off point or dispose of it as general waste. A persistent rodent problem means a high-risk material has been added. Empty and clean the bin completely before restarting.

The most common thing that goes wrong is not the compost. It is the expectation. Indoor composting in an HDB flat does not produce the same volume or speed as an outdoor pile. A 10-litre bucket filled with the right scraps and browns will yield about 3 litres of finished material every two to three months. That is not enough to feed a balcony garden; it is enough to supplement potting soil for a few pots.

If you produce more than about 2 kilograms of food waste per week, your home system will overflow or turn sour before it finishes. The better option is not a bigger bin but a community scheme or a bokashi setup that can handle the volume. The 2024 domestic recycling rate in Singapore was 12 percent, and food waste at 832,000 tonnes that year was the largest single stream in the domestic waste profile. Your home bin is a meaningful reduction at the individual level. It is not a substitute for the systemic food waste treatment infrastructure that Singapore is still building. The constraint is space, not will.