Purity (Arabic: طهارة, Tahara(h) ) is an essential aspect of Islam. It is the opposite of najis, things which are considered ritually impure are in the state of najāsa.
The question of : where is Quran is not proper if Muslims understand the Quranic order ( Obey Allah, obey the Messenger and your divine leaders)(4:59).
You can ask this person: Where it says in Quran to pray morning prayers in two Rak'ats, Dhuhr in four, Assr in four, Maghrib in three and Isha is four? The answer is: The Prophet Muhammad (SAWA) said that and Quran ordered us to obey him.
The Prophet (SAWA) said in Hadeeth al-Kisaa' which is narrated by many authentic narrators in Sunni and Shia books that Allah has created the universe for love of Ahlul Bayt (AS).
Allah (SWT) Has kept every Infallible totally pure, and kept any type of impurity far away from them, not that Allah has removed impurity from them, but kept them far away from any impurity i.e. Allah did not allow any impurity whatsoever to come near any Infallible. Quranic verse 33:33 stated: In fact, Allah wants to keep impurity away from you O, Ahlul Bayt إنما يريد الله ليذهب عنكم الرجس أهل البيت
There is a big difference between ليذهب عنكم to drive away any impurity from coming near you, and ليذهب منكم which means to drive away impurity from you which can mean driving away any existing impurity. Allah (SWT) never said that, but He said ليذهب عنكم which means that Ahlul Bayt never had any impurity, and Allah kept impurity far away from coming near them.
All the existence of the Infallible is absolute pure in the highest level which can never be compared with ordinary pious people.
These facts are very clear in Quran and the authentic Hadeeths. After believing in these facts, we do not need to go into details of the personal life of the Infallible, which are not necessary for us as it has nothing to do with our faith and practice and our responsibility to be sincere and humble servants of Allah and obedient followers of the Prophet (SWT) and Ahlul Bayt(AS).
After removing the blood, one time washing with tap or Kurr water is enough and two times with Qaleel water.
Dog is Najis whether it is used in hunting or guarding or otherwise.
Islam does not say that it is not allowed to have a dog as a pet, but it clearly says that dog is Najis and you must avoid any Najis item, otherwise your Prayers might be invalid if your cloth or body is Najis.
Hunting and guarding dogs are out of home usually, so there is no risk of Najasah on you from such dogs, but when the dog is at home as a pet , the risk is there.