は and が usage in a weird case

Question

I know that there are tons upon tons of resources on this question because I did a thorough search in google before this post but they don't seem to address my case. I saw this used in a tutorial that I recently looked at:

エーティーエムはありますか？

Here the tutorial used は for the ATM. And then I saw another example like this:

みずがありません。

Right here they use が for to say there is no water. Now I know that は and が are interchangeable but the tutorial won't accept my answer(I'm using Memrise). The question is:

How do you say "Is there an ATM?"

and my answer was

エーティーエムがありますか？

So is that a correct way to say it or is it not? What is it implying if it is. I saw SO MANY different things said for は and が. Here are some of them for example:

• が puts emphasis on the word before it and は puts emphasis on the word after it.
• は is used when we are familiar with the object and が is used when we are introducing an unknown one to the one we are talking to.
• は is used when you want to say that the object は puts an emphasis on is the only one that matters. "わたしは。。。" meaning I am... I don't care about other people, as far as I am concerned... and が is used to make the object "pop" and be distinguished from others: "わたしが。。。" if we use the が when we are in a group of people it means: Not the others but ME. It notes that out of all the people in the group I am the one that's concerned in this sentence.

There are many more since I looked at a lot of sources but every source seems to put a different spin on it. Are all of these bullet points correct?

I really seem to have a problem with learning by jumping from resource to resource since they all change so weirdly and they confuse me as to what's right and what isn't. Any idea how to help with that? Any particular resource I can look at and stick with?

Sorry for the long question I just needed to add these last few paragraphs to improve my learning in general.

Answer 1

みずがありません
is used when: we have run out of water; the tank is empty; this place is arid; what we don't have is water etc.

みずはありません
is used when: water isn't available; there's no water (you can have); when it comes to water, we don't have it etc.

Please note that water isn't subject in any English translation of みずがありません above. Without は attaches to みず, it never becomes a sentence that explains how water is, only working as description of another thing that has no water — because water is not a topic.

が marks subject (or, nominative case) while は marks topic. Though frequently misunderstood that は is what opposed to が, the real problem is whether は exists or not, as は is a particle that attaches to another particle.

が + は → は
を + は → は (archaic: をば)
に + は → には
で + は → では
と + は → とは
から + は → からは
　　︙
　　︙

Most if not all sentences in Japanese require a topic, explicitly or implicitly, to clarify its scope. A topic can be promoted from an existing in-sentence noun, or brought from outside of the sentence. But once a noun (phrase) becomes topic, it's treated as an out-of-sentence element.

ドナルド・トランプは正義か悪か？ (the topic has a place in the sentence)
lit. Donald Trump — is (he) a hero or a villain? or "Is Donald Trump a hero or a villain?"

象は鼻が長い。 (the topic has no place in the sentence)
lit. An elephant — the trunk is long. or "An elephant has a long trunk."

A sentence in Japanese needs a topic, just like a paragraph needs a heading. This is what linguists call topic-comment construction. Without topic people wouldn't understand what you are going to tell by the sentence (unless you're apparently bad at Japanese, then they'll guess). Subject of the sentence doesn't serve as topic.

Thus, if you ask エーティーエムがありますか？ out of nowhere, it'd only mean something, say, "Is this place ATM-equipped?" (i.e. not ATM-less area?) or "Are you an ATM-holder?" but unable to directly tell that you want to find an ATM around you. For this reason, practically what you're going to use to ask about existence of ATM on the street would be エーティーエムはありますか？

There are many more since I looked at a lot of sources but every source seems to put a different spin on it. Are all of these bullet points correct?

They all seem true, only are small parts of the whole truth. They're all about the usage of は, which is a great discussion that worth as thick a book as that about English articles. But never take them as the "essential function" of は, which is somewhat explained in this answer.

Answer 2

When you are simply saying There is something が will be used.

• ATMがあります
• みずがあります

These are very simple sentences which seem to have no context. Just like saying There's an ATM, There's water in English.

If は is used for the above sentences, it means slightly different.

A: I need to withdraw some money. Are there any banks around here?

B: [I don't know about banks but..] ATMはあります

In this case, は puts emphasis on ATM.

Another example is:

A: I need to buy water, milk, and eggs.

B: [(I don't know about)/(We don't have) milk and eggs but] みずはあります

This は puts emphasis on WATER.

When you are asking a question, Is there XXXXX? then は is used. I think it's safe to say that we don't use が if we ask a simple question like Is there XXXXX? (Note: が can be used in a case like Isn't there XXXXX? which is not a SIMPLE question)

ATMはありますか？

みずはありますか？