Where can I enter home reno cost of a well water filtration system that was required to use our water?

[TurboTaxSusan]

If you aren't using your home to earn income, then you can't claim a water filtration system as an expense. The exception would be if someone in the house hold had a severe chronic illness, and was issued a prescription for such a system. Then you can claim the cost as a medical expense. 

Otherwise, you can add the well water filtration system to the cost of your home when you sell it in the future, and report that on your tax return for that year.