אם יהיו שוב מים מתחת לכיור בלילה, נקרא לאינסטלטור מוקדם בבוקר.

Because Hebrew usually uses יש for there is / there are only in the present.

For other time frames, Hebrew normally switches to forms of להיות:

• יש מים = there is water
• היו מים = there was / were water
• יהיו מים = there will be water

So אם יהיו שוב מים... is the natural way to say if there is water again... when the condition refers to the future.

In Hebrew, מים is grammatically plural, even though in English water is an uncountable noun.

Because of that, verbs and adjectives often agree with מים in the plural:

• המים קרים = the water is cold
• יהיו מים = there will be water

So יהיו is plural because it agrees with מים, not because the speaker is thinking about multiple separate waters in the English sense.

That is a very common difference between English and Hebrew.

In English, future conditions usually use the present tense in the if clause:

• If there is water, we’ll call...

In Hebrew, it is very normal to use the future in both parts:

• אם יהיו... נקרא...

So this structure is standard Hebrew, not overly literal or awkward.

שוב means again.

Here it means that the problem has happened before, and the speaker is talking about it happening one more time:

• אם יהיו שוב מים... = if there is water again...

Its position is flexible, but where it appears now is very natural. You could also hear:

• אם שוב יהיו מים...

That version is also correct, with only a slight shift in emphasis.

The word מתחת means under / underneath, but in Hebrew it usually takes the thing underneath it with ל־:

• מתחת לשולחן = under the table
• מתחת למיטה = under the bed
• מתחת לכיור = under the sink

So the ל־ is part of the normal pattern after מתחת.

This is a very important Hebrew pattern.

The prepositions ב־, כ־, and ל־ often combine with the definite article ה־:

• ב + ה + בוקר → בבוקר
• ב + ה + לילה → בלילה
• ל + ה + כיור → לכיור

So even though you do not see a separate ה, it is built into the form.

That means:

• לכיור can mean to the sink or, in this phrase, under the sink
• בבוקר = in the morning
• בלילה = at night / during the night

In unpointed Hebrew writing, this is completely normal.

Because the verb itself already tells you the subject.

נקרא is the future form for we:

• נקרא = we will call

Hebrew often leaves out subject pronouns when the verb already makes the subject clear. So:

• נקרא לאינסטלטור = we will call the plumber

You could say אנחנו נקרא, but it is usually unnecessary unless you want extra emphasis.

Because לקרוא changes pattern depending on the meaning.

When it means to call someone, Hebrew usually uses ל־:

• לקרוא לרופא = to call the doctor
• לקרוא לאינסטלטור = to call the plumber

When לקרוא means to read, it takes a direct object:

• לקרוא ספר = to read a book
• לקרוא את הספר = to read the book

So the ל־ after נקרא tells you that the meaning here is call, not read.

מוקדם בבוקר means early in the morning.

This is a very common Hebrew time expression:

• מוקדם בבוקר = early in the morning
• מאוחר בלילה = late at night

The order sounds natural because מוקדם describes the time phrase בבוקר as a whole. English does the same thing: early in the morning, not usually in the morning early.

Yes. The form נקרא can mean we will call or we will read, because both meanings come from לקרוא.

Context tells you which one is intended.

Here, לאינסטלטור makes the meaning clear:

• נקרא לאינסטלטור = we will call the plumber

If it were נקרא את הספר, it would mean:

• we will read the book

So this is a good example of how Hebrew often relies on context and sentence pattern to disambiguate meaning.