Hvis der ligger vand på gulvet, tørrer jeg det op med en karklud.

Because vand is being used as an uncountable mass noun, like water in English. In Danish, uncountable nouns often appear without en or et.

So:

• der ligger vand på gulvet = there is water on the floor
• not der ligger et vand på gulvet

You would only use an article if you were talking about a specific countable instance, which is not the case here.

Here, der is a dummy subject, similar to English there in there is.

So der ligger vand literally looks like there lies water, but in natural English it means there is water or there’s water.

This der does not mean a physical place by itself. It is there because Danish often uses this pattern when introducing the existence or presence of something.

Both can be possible, but they are not exactly the same.

• der er vand på gulvet = there is water on the floor
• der ligger vand på gulvet = there is water lying on the floor

Using ligger gives a more physical image: the water is spread out on the floor, like a spill. Danish often uses verbs like ligge, stå, and sidde where English would just use be.

So ligger is very natural here because spilled water is understood as something lying on a surface.

This is because Danish main clauses follow the verb-second rule.

The first part of the sentence, Hvis der ligger vand på gulvet, is a subordinate clause placed first. After that, the main clause begins, and its finite verb must come before the subject:

• Hvis der ligger vand på gulvet, tørrer jeg det op ...

If the main clause stood alone, it would be:

• Jeg tørrer det op med en karklud.

But when something else comes first, Danish inverts the normal order:

• Nu tørrer jeg det op.
• Hvis ..., tørrer jeg det op.

This is a very common pattern in Danish.

Because the sentence begins with a subordinate clause introduced by hvis.

• Hvis der ligger vand på gulvet, = subordinate clause
• tørrer jeg det op med en karklud. = main clause

In standard Danish writing, a comma is used to separate these parts.

Because vand is a neuter noun in Danish, so when you refer back to it with a pronoun, you use det.

Even though vand is uncountable, it still has grammatical gender, and that gender is neuter.

So:

• vand → det

That is why you get:

• tørrer jeg det op

Tørre op is a verb + particle combination, and it means to wipe up, to dry up, or to mop up, especially liquid that has spilled.

So:

• tørre by itself can mean dry or wipe
• tørre op specifically means wipe up / dry up something spilled

The particle op is often separated in main clauses:

• Jeg tørrer det op.

With a pronoun object like det, the usual order is:

• verb + pronoun + particle
• tørrer det op

That word order is completely normal.

Because gulvet is the definite form, meaning the floor.

The noun is:

• et gulv = a floor
• gulvet = the floor

Danish often adds the definite ending directly to the noun instead of using a separate word like the.

So på gulvet means on the floor.

A karklud is a dishcloth or cleaning cloth, especially the kind used in the kitchen for wiping surfaces.

It is not exactly the same as a towel. In this sentence, it is the cloth you use to wipe up the water.

The word is made up of:

• kar = dishes / kitchenware
• klud = cloth

So med en karklud means with a dishcloth.

Because Danish often uses the present tense for general situations, habits, or what someone normally does in a situation like this.

So the sentence can mean something like:

• if there is water on the floor, I wipe it up with a dishcloth

This is not necessarily talking about only one specific moment. It can describe a routine or a normal response.

That is why the present tense sounds natural in both clauses.