Besok pagi ada gotong royong di komplek kami untuk membersihkan selokan yang tersumbat.

In this sentence, ada is being used in its existential sense: there is / there will be.

So:

• Besok pagi ada gotong royong... = Tomorrow morning there will be a community work activity...

It does not mean to have here. Indonesian often uses ada to introduce the existence of an event, person, or thing.

Examples:

• Ada rapat besok. = There’s a meeting tomorrow.
• Ada tamu di rumah. = There’s a guest at home.

Besok pagi is the most natural and standard way to say tomorrow morning.

• besok = tomorrow
• pagi = morning

Together, besok pagi means tomorrow morning.

You may sometimes hear pagi besok, but besok pagi is far more common in everyday Indonesian.

Compare:

• besok pagi = tomorrow morning
• tadi pagi = this morning / earlier this morning
• kemarin pagi = yesterday morning

So the time expression is very natural as written.

Gotong royong is a very important Indonesian cultural expression. It refers to people working together voluntarily for the common good, especially in a neighborhood or village.

In English, there is no perfect single-word translation. Depending on context, it can mean:

• community service
• communal work
• neighborhood clean-up
• mutual cooperation

In this sentence, it most likely refers to neighbors gathering to clean the clogged drain together.

So gotong royong is not just “work”; it carries the idea of shared effort and cooperation.

Di komplek kami means in our housing complex / in our neighborhood area.

Breaking it down:

• di = in / at
• komplek = housing complex, residential area
• kami = our

A useful note: komplek is a very common everyday spelling/pronunciation, while kompleks is the more standard spelling.

So this phrase tells you where the event is happening.

This is a very common question for English speakers.

Both kami and kita can mean we/us/our, but they are different:

• kami = we/us/our, excluding the listener
• kita = we/us/our, including the listener

So komplek kami means our housing complex, but the speaker is not necessarily including the person being spoken to as part of that group.

If the speaker wanted to include the listener as part of the same community, komplek kita might be used instead.

This distinction is very important in Indonesian.

Here, untuk means to or in order to and introduces the purpose of the gotong royong.

So:

• untuk membersihkan selokan yang tersumbat
• = to clean the clogged drain

Although untuk can also mean for, in this sentence it is best understood as a purpose marker.

Examples:

• Saya belajar untuk ujian. = I study for the exam.
• Dia datang untuk membantu. = He/She came to help.

Here, it answers the question: What is the gotong royong for?

Membersihkan comes from the root bersih, which means clean.

The form membersihkan means to clean something.

A simple way to understand it:

• bersih = clean
• membersihkan = to make clean / to clean

This is a verb with an affix pattern that turns the idea of clean into an action done to an object.

Since there is an object after it:

• selokan = the drain

the verb needs the transitive sense:

• membersihkan selokan = to clean the drain

So membersihkan is the appropriate form because someone is actively cleaning something.

Selokan means a drain, ditch, or drainage channel, especially the kind you see along roads or in residential areas.

It is not usually a fancy indoor drain. It more often refers to an outdoor drainage channel that carries rainwater or wastewater.

So in this sentence, it most likely means a neighborhood drain that has become blocked.

Yang tersumbat means that is clogged or which is blocked.

Breaking it down:

• yang = a relative marker, often like that / which / who
• tersumbat = clogged, blocked

So:

• selokan yang tersumbat = the drain that is clogged

This is a relative clause modifying selokan.

Very literally:

• selokan = drain
• yang tersumbat = which is blocked

So the whole phrase identifies which drain they are cleaning.

In tersumbat, the prefix ter- usually gives the idea of a state or resulting condition.

So:

• sumbat relates to blocking or plugging
• tersumbat = blocked / clogged

In this sentence, tersumbat describes the drain’s condition, not an intentional action by a subject.

So it is most naturally understood as:

• selokan yang tersumbat = the drain that is clogged

For learners, the easiest way here is to treat tersumbat as an adjective-like form meaning blocked/clogged.

Indonesian often does not use a copula like is/are in places where English does.

So:

• selokan yang tersumbat literally looks like:
• drain that clogged

but naturally means:

• the drain that is clogged

This is very normal in Indonesian. The language often leaves out is/are when describing something.

Other examples:

• Rumah itu besar. = That house is big.
• Dia sakit. = He/She is sick.

So there is nothing missing; the sentence is grammatically complete.

Yes, some parts could be rearranged, but the original order is very natural.

Original:

• Besok pagi ada gotong royong di komplek kami untuk membersihkan selokan yang tersumbat.

This starts with the time, which is very common in Indonesian:

1. Besok pagi = time
2. ada gotong royong = event exists / there will be an event
3. di komplek kami = place
4. untuk membersihkan... = purpose

You could also say:

• Ada gotong royong besok pagi di komplek kami...

This is still understandable, but it shifts the focus slightly to the existence of the event first. The original version sounds smooth and natural.

Komplek is common in everyday speech and writing, but it is a bit less formal than kompleks.

So:

• komplek = common, conversational
• kompleks = more standard/formal spelling

In casual messages, neighborhood announcements, or speech, komplek is very normal.

Everything else in the sentence is fairly neutral, so the overall tone is natural everyday Indonesian.

Most naturally, it describes the location of the gotong royong:

• There will be a gotong royong in our housing complex...

Then the purpose is:

• to clean the clogged drain

In real context, the drain is probably also in that same area, so the meaning is clear.

Grammatically, Indonesian often relies on common sense and context instead of marking every relationship very explicitly. In this sentence, the listener will naturally understand that the community work is happening in the speaker’s complex, and the clogged drain is there too.

Yes, it sounds natural and idiomatic.

It has a very normal structure for giving local news or making an announcement:

• time first
• event introduced with ada
• place
• purpose

A native speaker would understand it immediately as something like a neighborhood announcement about a communal clean-up.

The only small thing to note is that komplek is the more casual spelling; kompleks would be slightly more formal. Other than that, the sentence is very natural.