Der Wasserdruck ist zu niedrig.

Because Wasserdruck is a masculine noun in German: der Wasserdruck.

In German, every noun has a grammatical gender:

• der = masculine
• die = feminine
• das = neuter

There is no reliable way to guess every noun’s gender just from the English meaning, so you usually learn the article together with the noun:

• der Wasserdruck = the water pressure

Also, in compound nouns like Wasserdruck, the gender is determined by the last part of the compound:

• das Wasser = water
• der Druck = pressure
• therefore der Wasserdruck = water pressure

Wasserdruck is a compound noun, which is very common in German.

It is made from:

• Wasser = water
• Druck = pressure

So literally it is water-pressure.

German often combines words into one noun where English might use two separate words. Some similar examples:

• die Wasserflasche = water bottle
• die Zahnbürste = toothbrush
• der Kühlschrank = refrigerator

So Wasserdruck is just one noun, written as one word.

Ist is the 3rd person singular form of the verb sein = to be.

The subject is der Wasserdruck, which is singular, so German uses:

• ich bin = I am
• du bist = you are
• er/sie/es ist = he/she/it is

Since der Wasserdruck is treated like it, the sentence uses:

• Der Wasserdruck ist ... = The water pressure is ...

There is an important difference:

• niedrig = low
• zu niedrig = too low

So:

• Der Wasserdruck ist niedrig. = The water pressure is low.
• Der Wasserdruck ist zu niedrig. = The water pressure is too low.

The word zu here means too in the sense of more/less than is acceptable or needed.

This is very common in German:

• zu teuer = too expensive
• zu kalt = too cold
• zu langsam = too slow

Because niedrig is being used as a predicate adjective, not directly before a noun.

Compare:

1. Predicate adjective after sein:

   • Der Wasserdruck ist zu niedrig.
   • The adjective stays in its basic form: niedrig

2. Attributive adjective before a noun:

   • der niedrige Wasserdruck
   • Here the adjective gets an ending: niedrige

So after verbs like sein (to be), adjectives usually do not take endings:

• Das Wasser ist kalt.
• Der Raum ist groß.
• Die Leitung ist kaputt.

It is in the nominative case, because it is the subject of the sentence.

In this sentence:

• Der Wasserdruck = the thing being talked about
• ist = is
• zu niedrig = too low

So der Wasserdruck is the subject, and subjects are normally in the nominative.

That is why the article is der here.

Yes. This is standard German main-clause word order.

The sentence pattern is:

Subject + verb + rest

• Der Wasserdruck
  • ist
    • zu niedrig

This is very normal in simple statements.

German requires the finite verb to be in the second position in a main clause:

• Der Wasserdruck ist zu niedrig.

You could also move another element to the front for emphasis, but then the verb still stays second:

• Zu niedrig ist der Wasserdruck.
  This is grammatical, but much less neutral and less common.

A rough English-friendly guide:

• Wasserdruck ≈ VAH-ser-drook
• niedrig ≈ NEE-drig or NEE-drihkh depending on accent

A few pronunciation notes:

• W in German sounds like English v
• a in Was- is like ah
• u in Druck is a short vowel, somewhat like the vowel in put, but not exactly
• final -ig in many words is often pronounced something like -ikh in standard German, so niedrig is often closer to NEE-drihkh

If you want a simple learner version, saying VAH-ser-drook ist tsoo NEE-drig will be understood.

Because this zu is not the to used with an infinitive verb. It is a different word.

German zu has more than one use:

1. zu = too

   • zu niedrig = too low
   • zu teuer = too expensive

2. zu with an infinitive

   • Ich versuche zu helfen. = I’m trying to help.

In Der Wasserdruck ist zu niedrig, zu belongs directly with the adjective niedrig, so it comes right before it.

Yes, if the context already makes it clear that you mean water pressure.

• Der Wasserdruck ist zu niedrig. = specific and clear
• Der Druck ist zu niedrig. = The pressure is too low

Without context, der Druck could refer to other kinds of pressure too, so Wasserdruck is more precise.

No. Niedrig is the most direct and common adjective for something like pressure, level, or amount being low.

But depending on context, German can also use:

• gering = low, small, slight
• schwach = weak

For example:

• Der Wasserdruck ist zu niedrig. = The water pressure is too low.
• Der Wasserdruck ist zu schwach. = The water pressure is too weak.

For technical or everyday statements about measured pressure, zu niedrig is usually the best choice.

Yes, absolutely. This is a very natural sentence for practical everyday situations.

It could be used when:

• the shower is weak
• the tap is not running properly
• a building has plumbing issues
• a system does not have enough water pressure

It sounds like a normal statement someone might make when diagnosing a problem:

• Der Wasserdruck ist zu niedrig.

The easiest yes/no question is:

Ist der Wasserdruck zu niedrig?
= Is the water pressure too low?

German often forms yes/no questions by putting the verb first:

• statement: Der Wasserdruck ist zu niedrig.
• question: Ist der Wasserdruck zu niedrig?

You could also ask for more detail:

• Warum ist der Wasserdruck zu niedrig? = Why is the water pressure too low?
• Ist der Wasserdruck hier immer zu niedrig? = Is the water pressure here always too low?

A simple past meaning in everyday German is often expressed with sein in the perfect tense:

Der Wasserdruck ist zu niedrig gewesen.
= The water pressure was too low.

In more formal writing, you might also see the simple past:

• Der Wasserdruck war zu niedrig.

Both are correct, but war is very common and natural here.

Examples:

• Gestern war der Wasserdruck zu niedrig. = Yesterday the water pressure was too low.
• Am Morgen ist der Wasserdruck zu niedrig gewesen. = In the morning the water pressure was too low.