Drikkevannet og langtidsmaten kontrolleres.

Because Norwegian forms compounds as one word much more often than English does.

• drikkevann = drikke
  • vann → drinking water
• langtidsmat = langtid(s)
  • mat → long-term food, stored food, or provisions for long-term use

Then the definite ending is added to the whole compound:

• drikkevann → drikkevannet
• langtidsmat → langtidsmaten

A useful rule: in Norwegian, if English would write something like drinking water or long-term food, Norwegian will often make it one word.

Those are the definite endings, basically the Norwegian equivalent of the.

• vann → vannet = the water
• mat → maten = the food

So:

• drikkevannet = the drinking water
• langtidsmaten = the long-term food / the stored food

The ending depends on the gender of the main noun at the end of the compound:

• vann is neuter, so it takes -et
• mat is common gender, so it takes -en

The last part of the compound decides the gender and inflection.

The basic forms are:

• drikkevann
• langtidsmat

These are the indefinite forms of the compounds.

With mass nouns like water and food, Norwegian often uses the bare noun without an article in the indefinite sense, just like English often does:

• Vi trenger drikkevann. = We need drinking water.
• De lagrer langtidsmat. = They store long-term food.

So you should not expect something like a drinking water in normal use.

Kontrolleres is the present passive form of kontrollere.

• kontrollerer = checks / is checking
• kontrolleres = is checked / are checked or is being checked / are being checked

So the sentence is passive: the water and the food are receiving the action, not doing it.

A very literal breakdown is:

• kontrollere = to check / inspect
• kontrolleres = to be checked / inspected

The -s marks the passive voice.

This is a very common Norwegian pattern, especially in formal, written, administrative, or instructional language.

Compare:

• De kontrollerer drikkevannet. = They check the drinking water.
• Drikkevannet kontrolleres. = The drinking water is checked.

Norwegian also has another common passive construction:

• Drikkevannet blir kontrollert.

That means almost the same thing. In many contexts, -s passive can sound a bit more formal or compact than blir + past participle.

Because drikkevannet og langtidsmaten is one combined subject linked by og = and.

English does the same thing:

• The water and the food are checked.

Norwegian uses one finite verb for the whole subject:

• Drikkevannet og langtidsmaten kontrolleres.

So even though two nouns are mentioned, they form a single coordinated subject.

Because Norwegian verbs do not change for singular vs. plural the way English verbs do.

That means the same present-tense verb form is used regardless of number:

• Vannet kontrolleres. = The water is checked.
• Varene kontrolleres. = The goods are checked.
• Drikkevannet og langtidsmaten kontrolleres. = The drinking water and the long-term food are checked.

So even though the whole subject is plural in meaning because of and, the verb form stays the same.

Each noun is singular in form:

• drikkevannet = singular definite
• langtidsmaten = singular definite

That may feel strange to an English speaker, but both water and food are usually treated as mass nouns, not countable items. Norwegian often uses the singular definite form to refer to a specific supply or category:

• the drinking water
• the stored food

When they are joined by og, the whole subject becomes plural in meaning, even though each noun itself is singular.

Yes. That is also correct.

Both versions are passive:

• Drikkevannet og langtidsmaten kontrolleres.
• Drikkevannet og langtidsmaten blir kontrollert.

In many situations, the difference is mostly stylistic:

• kontrolleres = shorter, often more formal or impersonal
• blir kontrollert = very common, often a bit more conversational or event-focused

A learner should understand both.

This sentence uses the basic Norwegian declarative pattern:

subject + finite verb

• Drikkevannet og langtidsmaten = subject
• kontrolleres = finite verb

So the sentence structure is very straightforward.

If you move another element to the front, Norwegian still keeps the finite verb in second position:

• Hver dag kontrolleres drikkevannet og langtidsmaten. = Every day, the drinking water and the long-term food are checked.

That is a key Norwegian word-order rule: the finite verb normally comes second in main clauses.