# How to Stop Drains Blocking Again | KL Plumbing Handbook

> Habits that reduce repeat blockages in KL homes: grease disposal, grease traps, strainers, routine flushing and what never to pour away.

URL: https://klplumbing.my/guide/prevent-blocked-drains/
Last-Modified: 2026-11-15
Author: KL Plumbing Handbook editors

## Most blockages are built up slowly

You know how a drain seems to block “suddenly”? It rarely does. Grease, hair, soap, food scraps and silt build up inside the pipe for weeks or months.

By the time your sink drains slowly, the pipe has been narrowing for a while. The good news is that a few small habits help you prevent blocked drains in most homes.

We’ll cover what to keep out of your drains, the simple tools that help, and a routine you can stick to. If a drain is already misbehaving, start with our 

Blocked Drains and Sinks section

[/blocked-drains-and-sinks/ →](/blocked-drains-and-sinks/)

.

## Kitchen: grease is the main enemy

Grease is the top cause of blocked kitchen sinks, so keep it out of the pipe. Cooking oil and fat are liquid when hot and solid when cool. Poured down the sink, they cool inside the pipe and stick to the walls.

Food scraps and soap then stick to the grease. Indah Water Konsortium (IWK) has long pointed to grease as a leading reason sewer pipes overflow. In Malaysian kitchens that cook with plenty of oil, kitchen grease in the drain is the most common cause we see.

![Used cooking oil poured into a sealed bottle beside a Malaysian kitchen sink](/images/content/used-cooking-oil-poured-into-a-sealed-bottle-besid.webp)

**Habits that help:**

-   **Wipe pans and plates** with kitchen paper before washing. Put the paper in the bin.
-   **Collect used oil** in an old bottle or tin with a lid, and bin it once full. Better still, drop it at a collection point. PETRONAS Dagangan had expanded its used cooking oil collection to 100 stations by June 2026.
-   **Scrape food scraps** into the bin, not the sink.
-   **Use a sink strainer** to catch rice, vegetable pieces and bones.
-   **Run hot water** after washing greasy dishes, as a habit rather than a cure.

![Stainless steel mesh strainer sitting in a kitchen sink plughole with food scraps caught in it beside a dish rack](/images/content/stainless-steel-mesh-strainer-sitting-in-a-kitchen.webp)

### Grease traps

A grease trap is a small box that separates grease from water before it reaches the drain. A grease trap at home makes sense if you fry often. Malaysian eateries must install and service one to renew their business licences, and that rule exists because grease causes so many sewer blockages.

At home, the trap needs regular cleaning. Otherwise it fills up, smells and blocks. If you have one, put it on your monthly list.

## Bathroom: hair and soap

Hair is the main cause of blocked showers and floor traps. It catches on the trap and builds a mat with soap scum.

-   **Fit hair catchers** over shower drains and floor traps.
-   **Lift floor trap covers** and clear hair every week or two.
-   **Rinse basins** after shaving, brushing and washing hair.
-   **Do not wash paint, plaster or tile grout** down any drain. They set hard.

For toilets, the rules are different. Our guide on 

what not to flush

[/guide/what-not-to-flush/ →](/guide/what-not-to-flush/)

 covers wet wipes, pads and tissue. IWK has warned that wipes, diapers, sanitary pads and even clothing can clog sewer pipelines.

## What not to pour down any drain

Four things cause most of the damage: oil, rice, coffee grounds and anything that sets hard. The table below shows what to keep out and why.

| Do not pour | Why |
| --- | --- |
| Cooking oil and fat | Sets in the pipe and traps other waste |
| Coffee grounds | Clump together and settle in traps |
| Rice and starchy food | Swells and sticks |
| Paint, plaster, cement, grout | Sets hard inside the pipe |
| Strong chemicals and solvents | Damage pipes, seals and the sewer system |
| Medicines | Harm the water system |

## Tenants and guests

Many blockages in rented homes come from people who don’t know the house rules. A short note near the kitchen sink and in each bathroom fixes most of it.

-   No oil in the sink
-   Scraps in the bin
-   Nothing but toilet paper in the toilet

Landlords can add the same points to the house rules in the tenancy agreement. It also reduces arguments later about who caused a blockage.

## Outdoor drains

Keep outdoor drains clear of leaves and silt, especially before heavy rain. In landed houses, this is your job, not the council’s, once the drain is inside your boundary.

Check where each roof downpipe empties too. Our guide to an 

outdoor drain overflowing after rain

[/guide/outdoor-drain-overflowing-rain/ →](/guide/outdoor-drain-overflowing-rain/)

 covers this.

## A simple check schedule

Follow this schedule and most problems get caught while they’re still small.

| How often | What to do |
| --- | --- |
| Daily | Wipe greasy pans, use the sink strainer |
| Weekly | Clear hair from shower drains and floor trap covers |
| Every two weeks | Pour water into floor traps in unused rooms |
| Monthly | Clean the grease trap if you have one; flush kitchen sink with hot water |
| Before heavy rain | Clear gutters and outdoor drains |
| Yearly | Check all traps, look at outdoor inspection chambers |

## Notice early warning signs

Slow drainage is the first sign of a coming blockage. Act when you notice any of these:

-   A sink or shower that drains more slowly than usual
-   Gurgling from a drain or floor trap
-   A smell that comes back after cleaning
-   Water pooling around a floor trap after a shower

At that stage, cleaning the trap and using a plunger often solves it. Leave it, and the next stage is a full blockage. Our 

comparison of drain chemicals, plungers, drain snakes and hydro jetting

[/guide/drain-chemicals-vs-plunger-vs-snake-vs-hydro-jetting/ →](/guide/drain-chemicals-vs-plunger-vs-snake-vs-hydro-jetting/)

 explains what to use when.

## Landed house and condo notes

Where you live decides who fixes the problem, so know which one applies to you.

**Landed house.** You are responsible for drains inside your boundary, so a yearly look in the inspection chambers is worthwhile. Silt and roots can build up there, and a quick check costs far less than clearing a backed-up line.

**Condo unit.** What goes down your drain ends up in a shared stack. Grease and wipes from one unit can block the stack for everyone below. Good habits help your neighbours too.

## When to call a plumber

Call a plumber if a drain stays slow after you have cleaned the trap and used a plunger. The same goes if more than one fixture is affected, or if water backs up through a floor trap.

A plumber can clear deeper build-up that household tools cannot reach. They can also tell you if a pipe has a sag or damage that keeps catching waste.

If you want to prevent blocked drains from coming back, ask for a drain check at the same visit. Then use the schedule above to keep the pipes clear.

## Questions people ask

Is hot water enough to clear grease?expand\_more

It helps for a short while. Hot water melts fresh grease and moves it further down the pipe, but as the water cools the grease sets again further along, where it is harder to reach. The better habit is to keep grease out of the sink in the first place.

Do I need a grease trap at home?expand\_more

Not every home does. A small under-sink grease trap is useful in kitchens that cook with a lot of oil every day. It only works if you clean it regularly, otherwise it becomes a smelly blockage of its own.

How often should I clean floor trap covers?expand\_more

Whenever hair and debris build up. In a busy bathroom that may be weekly. A quick lift, wipe and rinse takes a minute and prevents most bathroom blockages.

Are enzyme drain cleaners safe to use regularly?expand\_more

Enzyme or bacterial products are gentler than caustic cleaners and some people use them as routine maintenance. They work slowly and are not a fix for a blocked drain. Read the label and follow the instructions.

Keep reading

Learn more about blocked drains and sinks

Causes of clogged sinks, floor traps and outdoor drains, and safe ways to clear them.

Open the Blocked Drains section

[/blocked-drains-and-sinks/ →](/blocked-drains-and-sinks/)

About the authors

KL Plumbing Handbook editors

The KL Plumbing Handbook editors write plain-language guides on home plumbing problems, repair costs and hiring a plumber for homes in Kuala Lumpur and the Klang Valley. Each guide covers one problem and states the source and date of every cost figure.

Spotted an error? 

Send a correction

[/contact/ →](/contact/)

. See our 

editorial policy

[/editorial-policy/ →](/editorial-policy/)

.

## Related guides

Bad Smell from a Drain or Floor Trap Why bathrooms and drains smell of sewage: dry water seals, missing traps or collars, vent problems and toilet seals, with simple checks. Read guide arrow\_forward

[/guide/bad-smell-drain-floor-trap/ →](/guide/bad-smell-drain-floor-trap/)

 

Drain Chemicals vs Plunger vs Drain Snake vs Hydro Jetting Compare drain chemicals, plungers, drain snakes and hydro jetting for safety and results, and which suits which blockage. Read guide arrow\_forward

[/guide/drain-chemicals-vs-plunger-vs-snake-vs-hydro-jetting/ →](/guide/drain-chemicals-vs-plunger-vs-snake-vs-hydro-jetting/)

 

Gurgling Drains: What the Sound Means Gurgling is often an early sign of a partial blockage or a venting problem. What it means, which fixtures matter, and what to check. Read guide arrow\_forward

[/guide/gurgling-drain-sound/ →](/guide/gurgling-drain-sound/)

 

Outdoor Drain Overflowing After Rain Why landed-house drains overflow in heavy Klang Valley rain: debris, silt and downpipes, safe clearing, and when to report to the council. Read guide arrow\_forward

[/guide/outdoor-drain-overflowing-rain/ →](/guide/outdoor-drain-overflowing-rain/)