Read the following sections of the Iowa landlord tenant statute:

Landlord to maintain fit premises.
Noncompliance by the landlord - in general.
Wrongful failure to supply heat, water, hot water or essential services.
Tenant's remedies for landlord's unlawful ouster, exclusion, or diminution of service.

Should be something in there that would help you.

https://www.legis.iowa.gov/law/iowaC...562A&year=2015