Si el bacalao está demasiado salado, lo dejaré en agua un rato antes de cocinarlo.

Because this is a normal if + future result pattern in Spanish:

• Si
  • present tense
• future tense in the main clause

So:

• Si el bacalao está demasiado salado = if the cod is too salty
• lo dejaré en agua... = I will leave it in water...

This is very common in Spanish:

• Si tengo tiempo, iré. = If I have time, I’ll go.
• Si llueve, nos quedaremos en casa. = If it rains, we’ll stay home.

Spanish does not normally use the future after si in this kind of sentence. So si estará would be wrong here.

Estar is used because the sentence is talking about the cod’s current condition: it is too salty at this moment.

• Está salado = it tastes/is salty right now
• Es salado would sound more like a general characteristic or classification, which is not what is meant here

With food, Spanish often uses estar for how it turns out or tastes:

• La sopa está fría.
• La carne está muy hecha.
• Está soso.

So está demasiado salado means the cod has ended up too salty.

Here demasiado means too.

It goes before the adjective:

• demasiado salado = too salty
• demasiado caro = too expensive
• demasiado difícil = too difficult

Be careful not to confuse it with muy:

• muy salado = very salty
• demasiado salado = too salty

So demasiado suggests there is a problem: the cod is saltier than desired.

Lo is a direct object pronoun meaning it, referring back to el bacalao.

• el bacalao is masculine singular
• so the pronoun is lo

Compare:

• Compraré el libro. Lo compraré mañana.
• Cocinaré el bacalao. Lo dejaré en agua primero.

Spanish often uses object pronouns where English also uses it, but the pronoun usually comes before the conjugated verb:

• lo dejaré
• lo cocinaré
• lo comeremos

Dejar here means to leave something somewhere for a period of time.

So lo dejaré en agua means I’ll leave it in water.

Spanish could sometimes use other verbs depending on the context, but dejar is very natural when you mean letting something sit or soak:

• Deja la ropa en agua.
• Dejé los garbanzos en remojo toda la noche.

Poner would mean to put, which focuses more on placing something somewhere, not on leaving it there for a while. In this sentence, the important idea is the soaking time, so dejar is a better choice.

En agua means in water.

Spanish often uses no article in expressions like this when talking about the substance in a general way:

• cocer en agua
• lavar con jabón
• hecho de madera

So dejarlo en agua means to leave it soaking in water, not in some specific previously mentioned water.

You could say en el agua in some contexts, but that would sound more like in the water as a specific body or container of water already known from the context.

Un rato means for a while.

It is a very common, everyday expression in Spanish. It is deliberately vague: not an exact number of minutes, just some time.

Examples:

• Espera un rato. = Wait a bit.
• Voy a descansar un rato. = I’m going to rest for a while.
• Déjalo en agua un rato. = Leave it in water for a while.

If the speaker wanted to be more precise, they could say:

• durante media hora
• durante una hora
• unos minutos

After antes de, Spanish uses an infinitive when the subject stays the same or is understood generally.

So:

• antes de cocinarlo = before cooking it / before I cook it

This is the normal structure:

• antes de salir
• antes de comer
• antes de hacerlo

Also, object pronouns are attached to the infinitive, which is why it is:

• cocinar + lo = cocinarlo

Not:

• antes de lo cocinar ❌

Because Spanish object pronouns can appear in different positions depending on the verb form.

With a conjugated verb, the pronoun normally goes before:

• lo dejaré
• lo como
• lo vi

With an infinitive, the pronoun attaches to the end:

• cocinarlo
• hacerlo
• comerlo

So both are normal; they just follow different placement rules.

In many contexts, especially in Spain, bacalao often refers to cod, and very often to salted cod in cooking contexts.

Because the sentence talks about the fish being too salty and soaking it in water before cooking, it strongly suggests salted cod that needs desalting.

This is culturally very natural in Spain, where salted cod is a common ingredient. So even though bacalao can mean cod generally, the context here clearly points to salted cod.

Yes, if the context is already clear.

• Si está demasiado salado, lo dejaré en agua un rato...

This would mean the same thing if everyone already knows you are talking about the cod.

Including el bacalao makes the sentence clearer and more self-contained. Spanish often drops subjects or repeated nouns when they are obvious, but it does not have to.

Because bacalao is a masculine noun:

• el bacalao

So the adjective must agree with it:

• salado

Agreement in Spanish:

• el pescado salado
• la sopa salada
• los platos salados
• las patatas saladas

Adjectives usually match the noun in gender and number.

Yes, mainly the cooking context.

The grammar is standard Spanish everywhere, but the idea of soaking bacalao to remove some salt feels especially familiar in Spain, where salted cod is a traditional ingredient in many dishes.

Also, un rato is a very common everyday expression in Spain, though it is widely understood elsewhere too.

So the sentence is not grammatically “Spain-only,” but it sounds very natural in a Spain food context.