Ok i did replied to you before i saw that you also wrote to me in my visitor message.
Read my privite message and answer all my questions so it will help us to understand what is the problem. And as for betta water yes you can use it. But you will need to do a lot of water changes so i am not sure if it ok with you or your perents. It might be expansive . You can go to the pet store and check your water make sure it goo , then you can just use your tap water with water conditioner. But either is fine