Learn Italian: Quel vassoio va lavato subito. - That tray must be washed immediately.

Using the verb andare followed by a past participle creates a passive voice that expresses necessity or obligation. Here, va lavato translates to "must be washed" or "needs to be washed." While deve essere lavato is also grammatically correct, the andare construction is extremely common and sounds much more natural to native ears.

Are there any restrictions on when I can use the andare + past participle construction?

Yes, this "passive of necessity" can only be used with simple tenses, such as the present (va lavato), the imperfect (andava lavato), or the future (andrà lavato). You cannot use it with compound tenses like the passato prossimo; in those cases, you have to use the verb dovere instead.

If the subject were plural, how would the sentence change?

The verb andare and the past participle must both agree in gender and number with the subject. If we were talking about multiple trays, Quel vassoio would become Quei vassoi, and the verb phrase would change to vanno lavati.

Why is it Quel vassoio instead of Quello vassoio?