She is asking about the ruling on drinking water over which Soorah Ya-Seen has been recited in order to treat doubts

Before discussing the shar‘i ruling, we advise you of that
which will help you to overcome the pain and get through the trial in the
best way that the believer can resort to, along with patience, and trying
to forget it by focusing on something else, and taking steady and patient
steps towards a remedy and not giving up or getting tired of doing so, and
not feeling frustrated by failure or by the slowness of results. Allah,
may He be glorified and exalted, is wise in all that He does. 

Everyone in this world should prepare himself to face
calamities and be exposed to all kinds of tests. This is the way of this
transient world which is full of trials and tribulations. Allah, may He be
glorified and exalted, says (interpretation of the meaning):

“And certainly, We shall test you with something of fear,
hunger, loss of wealth, lives and fruits, but give glad tidings to As‑
Saabiroon (the patient).

156. Who, when afflicted with calamity, say: ‘Truly, to
Allaah we belong and truly, to Him we shall return.’

157. They are those on whom are the Salawaat (i.e. who are
blessed and will be forgiven) from their Lord, and (they are those who)
receive His Mercy, and it is they who are the guided ones”

[al-Baqarah 2:155-157]. 

The believer always remembers the mercy of Allah, may He be
glorified and exalted, and he does not despair of attaining the generosity
of his Lord with healing and response to his supplication, even if it is
after a while. He looks at the tragedies of people around him, including the
poor who cannot find a mouthful of food, the sick person who is in agonising
pain at every moment, those who have been driven from their homes, prisoners
who are being tortured, those who are tested with their wives and children,
those who are afraid in their own homelands, and the long list of various
kinds of trials and tribulations. The one who ponders all that will realise
that he cannot escape the necessity of patience. So let it be the patience
of contentment, which is better than the patience of compulsion; this is the
patience for which Allah decrees reward. Athough the Messengers and Prophets
– who were the dearest and most beloved of mankind to Allah, may He be
glorified and exalted – were faced with calamities and trials that went on
for a long time, that did not lead them to give up and despair of the mercy
of Allah. Nooh (peace be upon him) remained among his people for a thousand
years less fifty (i.e., 950 years) during which they accused him and
resisted him. Ya‘qoob and Yoosuf (peace be upon him) were tested with a
lengthy separation until Ya‘qoob (peace be upon him) became blind. Moosa
(peace be upon him) was thrown out of his country and fled from it in fear.
Zakariya and Yahya (peace be upon them) were killed by the Children of
Israel. The people of ‘Eesa (peace be upon him) wanted to crucify him and
Allah raised him to Himself. Muhammad (blessings and peace of Allah be upon
him) was expelled by his people from his land; they reviled him and insulted
him and wanted to kill him. And the list is longer than that. If you want to
know more about that, look in the Book of Allah and ponder the meanings of
the verses that you read, and you will find the best consolation in that. 

So let us – weak slaves – not be hasty in seeking relief from
harm; let us do our duty of bearing it with patience and contentment, and
let us put our trust in Allah, may He be glorified and exalted, for He is
the Most Wise Who disposes of all the affairs of this world as He wills. 

This does not mean that one cannot seek help by means of
Islamically acceptable ruqyah in which Allah may decree there is healing.
Allah, may He be glorified and exalted, says (interpretation of the
meaning): “And We send down of the Qur’ân that
which is a healing and a mercy to those who believe (in Islâmic Monotheism
and act on it), and it increases the Zâlimûn (polytheists and wrong-doers)
nothing but loss” [al-Isra’ 17:82]. 

Al-‘Allaamah Muhammad al-Ameen al-Shanqeeti (may Allah have
mercy on him) says: 

The fact that it is a healing includes the heart and all its
diseases (i.e., spiritual diseases), such as doubt, hypocrisy and so on, as
well as healing for physical diseases if it is used in ruqya, as is
indicated by the story of the one who did ruqya for the man who had been
stung by a scorpion by reciting al-Faatihah. The report is saheeh and is
well known.

End quote from Adwa’ al-Bayaan,
3/253. 

But singling out specific verses or a specific soorah such as
Soorat Ya-Seen, for specific diseases and specifying a particular number of
times it should be recited or certain times for reciting these verses or
soorahs – none of this is the Sunnah of the Prophet (blessings and peace of
Allah be upon him) and there is no shar‘i evidence to support it. Rather we
are afraid that the one who does that will fall into innovation (bid‘ah).
This has been discussed previously on our website in the answer to question
no. 123155 

With regard to drinking water over which Soorat Ya-Seen has
been recited several times when he does not believe that it has any
particular virtue, there is nothing wrong with that, although it would have
been better to perform ruqyah with that which is proven according to shar‘i
evidence, such as reciting over the water Soorat al-Faatihah, al-Mi‘wadhatayn,
Aayat al-Kursiy and other passages that have been discussed on our website
under the heading of Ruqya, such as question no.
3476. 

There have also been a number of answers on our website which
suggest some means of dealing with doubts and waswaas (whispers from the
Shaytaan) that may cross one’s mind and be difficult to dispel. Please see
the following questions: 62839,
102851 and
107150. 

And Allah knows best.