Learn Swedish: Inget vatten behöver fyllas på. - No water needs to be topped up.

This is the passive infinitive, which is the focus of this lesson. We use it after verbs like behöver (needs) when the subject of the sentence isn't doing the action, but receiving it. Since the water isn't filling anything itself, but needs to be filled by someone else, we take the bare infinitive fylla and add an -s to make it fyllas.

What does the word på do at the end of the sentence?

It is part of the particle verb fylla på. While fylla just means to fill, adding the particle på changes the meaning to top up or refill. In Swedish, the particle stays separated and comes after the verb, even when the verb is in the passive form like fyllas.

Why is there no att before fyllas?

Even though the English translation says 'needs to be', Swedish treats behöver like a modal verb here, just like kan or måste. Modal verbs are followed directly by the infinitive form of the next verb, so we do not use att.

Why is it inget vatten instead of ingen vatten?