Wij melden de waterschade.

Both wij and we mean we.

• we is the more common unstressed form in everyday Dutch.
• wij is the stressed or full form. It can sound a bit more emphatic, contrastive, or formal.

So We melden de waterschade is also correct in many situations. Using wij can suggest something like we are the ones doing it.

Melden is the present tense form for wij.

Dutch present tense of melden:

• ik meld
• jij meldt / meld je
• hij/zij meldt
• wij melden
• jullie melden
• zij melden

So with wij, the verb looks the same as the infinitive: melden.

This is the normal word order for a simple main clause:

subject + finite verb + object

So:

• Wij = subject
• melden = finite verb
• de waterschade = object

Dutch main clauses follow the verb-second rule. Here the subject comes first, so the verb comes second. If another element came first, the verb would still stay in second position:

• Vandaag melden wij de waterschade.

Because waterschade is a de-word.

The main noun inside the compound is schade, and schade takes de:

• de schade
• therefore de waterschade

In Dutch compounds, the last part usually determines the grammatical gender and the article.

Because Dutch usually writes compound nouns as one word.

So:

• water
  • schade → waterschade

This is very common in Dutch. Where English often uses two words, Dutch often makes one compound word.

Other examples:

• huisdeur = house door / front door
• ziekenhuis = hospital
• regenjas = raincoat

In a normal full sentence like this, de is natural because it refers to a specific case of water damage.

• Wij melden de waterschade. = we are reporting the water damage

Without the article, waterschade sounds more general or less complete in this context. You might see it without an article in headlines, labels, or more general expressions, but in an ordinary sentence de waterschade is the expected choice.

Yes, melden can take a direct object directly, just like here:

• Wij melden de waterschade.

You can also add where or to whom you report it:

• Wij melden de waterschade bij de verzekering.
• Wij melden de waterschade aan de verhuurder.

So the thing being reported can stand directly after melden.

Here it is singular in form, but it often works like a mass or uncountable noun, similar to water damage in English.

So de waterschade usually refers to the damage caused by water as one situation or one case.

If you really want to talk about separate cases, Dutch can use a plural such as waterschades, but that is less common in ordinary everyday use than the singular mass-noun use.

It is neutral to slightly formal, mainly because of wij.

• Wij melden de waterschade. sounds fine in writing, customer service, forms, or clear standard Dutch.
• We melden de waterschade. sounds a bit more everyday and conversational.

Both are correct.