You need to provide a written notice of the problem. Utah Legal Services has a great notice you can use (see the link attached). As an issue of habitability, the landlord will have 3 days to fix the problem at which point you have a right to repair it yourself and abate rent for your out of pocket expenses.
I agree with the previous answer. Utah has a fit premises act. you can review it at UCA 57-22-4. Providing hot and cold water is a statutory requirement. There is also an implied warranty of habitability that attaches to all leases. I would provide notice, as previously recommended, cite the statute and explain that you need the problem fixed. Also, when communicating with your landlord about problems, consider using email, letters, or text messages to create a record.
This answer does not create an attorney-client relationship, and does not constitute legal advice pursuant to an attorney-client relationship. It should not be construed as legal counsel, but serves to provide a preliminary response to the facts presented.