My apologies for missing that part of your answer the first time.You did say "Energy Efficient Building Property".

According to my local gas company, this tax credit just got added back in (had expired as of Dec 2016), but renewed as part of the Bipartisan Budget Act of 2018...

But none of the boxes on the "Tell Us How Much You Paid for Energy-Saving Improvements" page are for a non-solar water heater.That's my problem.