Kami membersihkan longkang supaya air tidak naik ke jubin koridor lagi.

Because kami means we, but it excludes the person being spoken to.

• kami = we, not including you
• kita = we, including you

So if the speaker is talking to someone who did not help clean the drain, kami is the right choice.

Membersihkan means to clean something.

It comes from bersih = clean.
With the prefix and suffix, it becomes a verb meaning to make something clean / to clean.

A useful contrast:

• bersih = clean
• membersihkan longkang = clean the drain

So this verb is transitive, meaning it takes an object: here, longkang.

Longkang means drain, gutter, or a small drainage channel.

In this sentence, it refers to the place where water should flow away, so cleaning it helps prevent water from rising onto the corridor tiles.

Supaya means so that, in order that, or so that ... will not.

It introduces the purpose of the action:

• Kami membersihkan longkang = We cleaned the drain
• supaya air tidak naik... = so that the water would not rise...

So the second part explains why they cleaned the drain.

Because naik here works as an intransitive verb meaning to rise / go up.

The water itself is rising, so naik is enough:

• air naik = the water rises

Menaikkan usually means to raise something or cause something to go up, so it would need an object.

For example:

• Mereka menaikkan harga = They raised the price

But here the water is doing the action itself, so naik is correct.

Because tidak is used to negate verbs and adjectives, while bukan usually negates nouns or is used for identification.

Here, naik is a verb:

• air tidak naik = the water does not rise

Compare:

• Ini bukan longkang = This is not a drain

So tidak is the correct negative word in this sentence.

It means onto the corridor tiles or to the corridor tiles.

Breakdown:

• ke = to, toward, onto
• jubin = tile / tiles
• koridor = corridor

So naik ke jubin koridor gives the idea that the water rises up until it reaches or spills onto the tiled corridor area.

Because in Malay, the main noun usually comes first, and the word modifying it comes after.

So:

• jubin koridor = corridor tiles
  • main noun: jubin (tiles)
  • modifier: koridor (corridor)

This is similar to many Malay noun phrases where the head noun comes before the descriptive word or classifier noun.

Here lagi means again or any more, depending on how naturally you translate it into English.

With a negative, it often gives the sense of:

• not ... anymore
• not ... again

So:

• air tidak naik ke jubin koridor lagi = the water does not rise onto the corridor tiles anymore = so the water will not come up onto the corridor tiles again

It suggests this had happened before, and they want to prevent it from happening now.

Not by itself. Malay verbs usually do not change form for tense the way English verbs do.

So membersihkan could mean:

• cleaned
• are cleaning
• clean
• have cleaned

The exact time depends on context.

Because of the overall meaning, English may translate it as We cleaned the drain... or We are cleaning the drain..., depending on the situation.

Yes. Agar and supaya are both commonly used to mean so that / in order that.

So this would also be possible:

• Kami membersihkan longkang agar air tidak naik ke jubin koridor lagi.

In many contexts they are very similar. Supaya is very common in everyday usage.

The sentence as given is natural, but Malay word order can sometimes be flexible.

For example, lagi is often placed near the part it affects. In this sentence, putting it at the end sounds natural and clearly gives the meaning again / anymore.

The original version is good because it keeps the full idea together:

• action: Kami membersihkan longkang
• purpose: supaya air tidak naik ke jubin koridor lagi

So while some small rearrangements may be possible, the given order is clear and idiomatic.