Probably both houses were in same property and title was on the name of parents.
Isn’t IT!
And the title holder parent has deceased and property is not partitioned (equally) by boundaries.
The authority under whose jurisdiction property falls has a set procedure for such matters if NO WILL has surfaced; Intestate Succession…….and the prescribed forms, procedure, process is available in O/o Authority and even on website. Death certificates, legal heir certificate/affidavit (per local procedure-precedence) are basic requirements. Then authority shall act upon and transfer the ownership in the name of legal heirs. Obtain copy of updated mutations records showing share of legal heirs. This grants rights equal to that of owner to legal heirs.
Probably the property tax is also in the name of deceased parent.
If there is NO bar on more water connection then you may apply and take water connection in your name.
If the water connection is in the name of deceased parent/title holder then other brothers should not refuse to let take water which is otherwise essential.
Simultaneously involve elders of the family, LOCAL MC councilor etc and resolve the problem
Or lodging police complaint, complaint with MC, engaging lawyer, approaching courts etc are the recourses you may have to pursue.