That's a great point Rainbows. Did you add conditioner to the water to remove chlorine, chloramines, and heavy metals? That is very important.
Also, if I'm reading your post correctly, you did not mention if you have a heater. Bettas a tropical fish and need a heater. Temperature is favored around 76-82, that's usually where a comfortable temp falls.
If you look at the top of the this section. You will see a thread labeled "Sticky: Please answer these questions......" Please do answer those questions.