Kisima kikiwa safi, tunaweza kutumia maji yake kumwagilia bustani.

Kikiwa means if it is, when it is, or while it is, depending on context.

It breaks down like this:

• ki- = subject marker for kisima (a class 7 noun)
• -ki- = a tense/aspect marker often used for if/when
• -wa = the verb to be

So:

• kisima kikiwa safi = the well being clean / if the well is clean / when the well is clean

This is a very common Swahili way to make a subordinate clause.

Because they are doing two different jobs:

• the first ki- matches kisima and shows the subject is a class 7 noun
• the second -ki- is the marker meaning something like if/when

So kikiwa is not one repeated piece by accident. It is:

• ki-
  • -ki-
    • -wa

This kind of stacking is normal in Swahili verbs.

It can mean any of those, depending on context.

In this sentence, the most natural English choices are:

• If the well is clean, we can use its water to water the garden
• When the well is clean, we can use its water to water the garden

So -ki- often gives a sense of if/when rather than a strict one-word match.

Because the idea of being is already built into kikiwa.

Compare:

• Kisima ni safi = The well is clean
• Kisima kikiwa safi = If/when the well is clean

In the second one, -wa inside kikiwa already carries the meaning of be, so you do not add a separate ni.

Because safi is one of the adjectives that usually stays the same.

Some Swahili adjectives agree with the noun class, but many borrowed adjectives, especially common ones like safi, are often invariable.

So you get:

• kisima safi = a clean well
• maji safi = clean water
• nyumba safi = a clean house

The word safi stays safi.

Tunaweza means we can or more literally we are able.

It breaks down like this:

• tu- = we
• -na- = present tense
• -weza = be able

So:

• tunaweza kutumia = we can use

This is a very common Swahili structure: kuweza + infinitive.

This is a very important Swahili grammar point.

In maji yake, the possessive form agrees with the thing possessed, not with the owner.

Here the thing possessed is maji (water), so the possessive takes the form that matches maji:

• maji yake = its water

Even though the owner is kisima (the well), the possessive shape is determined by maji.

So the phrase means:

• the well’s water
• literally: its water

Maji means water, which is singular in English as a mass noun, but in Swahili it belongs to noun class 6 and takes class 6 agreement.

That is why you get forms like:

• maji yake
• maji haya
• maji mazuri

So even though the meaning is water, grammatically it behaves like a class 6 noun. This is something learners just have to get used to.

Because they do two different jobs:

• kutumia = to use
• kumwagilia = to water / for watering

So:

• tunaweza kutumia maji yake kumwagilia bustani

means:

• we can use its water to water the garden

This is similar to English:

• use the water to water the garden

The second infinitive expresses the purpose of using the water.

Kumwagilia means to water, to irrigate, or literally something like to apply/pour water onto.

It is related to the idea of pouring water, but in this sentence it is best understood as:

• to water the garden

So:

• kumwagilia bustani = to water the garden

This is more natural here than translating it very literally as just to pour.

Yes. That is a perfectly good alternative.

Compare:

• Kisima kikiwa safi, tunaweza kutumia maji yake kumwagilia bustani.
• Ikiwa kisima ni safi, tunaweza kutumia maji yake kumwagilia bustani.

Both mean roughly the same thing.

The version with kikiwa is a bit more compact and very natural Swahili. The version with ikiwa ... ni ... may feel easier to learners because its structure is more transparent.

Yes, it can, though the original order is very natural.

You could put the main idea first and the condition after it, but starting with Kisima kikiwa safi helps frame the condition immediately.

So the original sentence:

• Kisima kikiwa safi, tunaweza kutumia maji yake kumwagilia bustani.

naturally means:

• If/when the well is clean, we can use its water to water the garden.

Swahili often places this kind of condition first, just as English often does.