Use of "el" with feminine nouns beginning with a stressed "a"

[laepelba]

Okay, so I understand WHY words like "agua" and "águila" and "aula", etc. take "el" as the definite article because the stress is on the first syllable ... because of the sounds being directly next to each other....

But what about when there are two determiners? Would you say "toda el agua"? I can't really think of any more examples, although I'm sure there are some....

Thank you!!

[AngelicaDeAlquezar]

Masculine article is only used for reasons of euphony, but the gender of the word remains unchanged.

"Toda el agua" is correct.

El águila calva. -> La hermosa águila.
El aula nueva. -> Nuestra aula.
El hacha filosa. -> Esta hacha.
El hambre canina. -> Tengo mucha hambre.

[Rusty]

Yes, 'toda el agua' is correct. The adjectives and determiners will agree with the gender of the noun, despite which article is used.
Don't forget that words beginning with 'ha', that are stressed on the initial syllable, are also candidates.
el ama
el área
el hambre

However, not all feminine gender words that have a leading 'a' sound follow the 'rule' you're citing. There are some rule breakers. Here are three of them:
la a (the letter 'a')
la hache (the letter 'h')
la árabe (the Arabic woman)

[AngelicaDeAlquezar]

...and that's most likely because they're ellipses of the nature of those words:

la (letra) a
la (letra) hache
la (mujer) árabe

[Ronald Ross]

The "el" in noun phrases like "el águila" is derived from the Latin feminine pronoun "illa" which in Vulgar Latin was turning into a definite article. So in phrases such as "illa aquila" the two a's simply coalesced.