Usipotumia chujio, unaweza kunywa maji machafu.

Usipotumia packs several pieces into one verb:

• u- = you (singular)
• -si- = negative marker
• -po- = if/when
• -tumia = use

So u-si-po-tumia means if you do not use.

This is very common in Swahili: one verb can contain subject, negation, tense/condition, and the main verb stem all together.

Here, -po- gives the idea of if/when. In this sentence, the most natural English translation is simply if:

• usipotumia = if you do not use

Swahili has a few different conditional markers, and learners often compare -po- with -ki-. In many everyday contexts, though, translating -po- as if works well.

Grammatically, it is singular because of u-:

• u-si-po-tumia
• u-na-weza

So it literally addresses one person. However, Swahili often uses singular forms in general instructions or warnings, much like English can say If you don’t use a filter... to mean anyone.

If you wanted a true plural you all, it would be:

• Msipotumia chujio, mnaweza kunywa maji machafu.

Because each finite verb in Swahili normally shows its own subject.

• usipotumia = if you do not use
• unaweza = you can / you may

English repeats the subject too, but as a separate word:

• If you don’t use a filter, you may drink dirty water.

Swahili does the same thing inside the verbs.

After weza (be able, can), the next verb is usually in the infinitive form with ku-:

• unaweza kunywa = you can drink
• anaweza kwenda = he/she can go
• tunaweza kuona = we can see

So kunywa stays in the infinitive, just like English uses the plain verb after can.

Its core meaning is can / be able to, but in a warning like this it often expresses possibility:

• unaweza kunywa maji machafu = you may / could drink dirty water

So the sentence is not saying you definitely will drink dirty water. It means that this is a real risk or possibility.

Maji is a mass noun in Swahili, but grammatically it takes class 6 agreement, which often looks plural.

So even though English treats water as singular/uncountable, Swahili uses the agreement pattern that goes with maji. This is something you mostly just learn as part of the noun.

Because adjectives in Swahili usually agree with the noun class of the noun they describe.

The adjective stem is -chafu = dirty.
With maji, the agreement gives:

• maji machafu = dirty water

So ma- on machafu matches the noun maji.

Swahili generally does not use articles like English a/an/the.

So chujio can mean:

• a filter
• the filter
• filter in a general sense

The context tells you which one is meant. In this sentence, it is most naturally understood as a filter or a filter in general.

Chujio means filter or strainer—something used to remove unwanted material from a liquid.

In this sentence, because it is followed by a warning about dirty water, the natural meaning is a water filter. So the word is understood from the context, even though maji is not repeated after it.