Avoid excessive water use even if it does not cost you more money
22-2-2014 | IslamWeb
Question:
Assalamualaikum brother,i live in germany and i pay here rent for my room included current and water. as islam recommends,only few water to use for ghusl, i like it. hence i pay money also for my used water,and i am allowed here to use unlimited water.and to save money,i also cannot change the rules given by housemaster. in this case,should i also be careful about wasting water? barakallahu fiik.
Answer:
All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad 
is His Slave and Messenger.
In Islam, excessiveness is forbidden in an absolute sense. Allaah, The Exalted, says (what means): {… And be not excessive. Indeed, He does not like those who commit excess.}[Quran 6:141]
A Muslim is commanded to economize water use even if excessive water use does not cost him more money. Even if someone had an endless source of water, excessive water use is forbidden.
It was narrated on the authority of ‘Abdullaah ibn ‘Amr ibn Al-'Aas 
that the Messenger of Allaah passed by Sa‘d when he was performing Wudhoo' (ablution), and he said: "What is this extravagance?' Sa'd exclaimed, 'Is there extravagance in Wudhoo'?' The Prophet said: 'Yes, even if you are on the bank of a flowing river.'" [Ahmad and Ibn Maajah - Al-Albaani graded it Hasan (good)]
For more benefit, please refer to Fatwa 106655.
Hence, the fact that you pay rent including the cost of electricity and water, and that even if you economize in water use, you will not get back any part of this cost, this does not allow you to use water excessively.
Moreover, even if the average amount of water and electricity that is used by the tenant is not specified, it is left to be decided according to the commonly accepted practices of the community and the tenant is not allowed to use the provided utilities in excess of that.
Al-Mawsoo‘ah Al-Fiqhiyyah (Islamic jurisprudence Encyclopedia) reads: “The tenant should not exceed the usual limit in his use of the utilities in the rental if it is not restricted by specific terms or limits. This is because what is unrestricted by a limit is restricted by the commonly accepted practices of a given community. Muslim jurists stated that: What is determined by commonly accepted practices is tantamount to a stipulated condition ... If the landlord says: I rent it to you for whatever purpose you wish, the contract is valid; and the tenant can do whatever he wishes since the landlord has agreed to that; however, it is a condition that he uses it according to the commonly accepted practices of the community."
Allaah Knows best.