Running water through it? 

While you may be willing to live without heat/ac or hot water for a week.

I purchased a new furnace and water heater for another unit.

You will likely hear from a lot of people pushing syndications since your post is chumming the water.

I believe it is completely reasonable to have a clause in your lease that places a cap on utilities with any overage (proven by a bill) being the responsibility of the resident.Our clause states that any electrical bill (we don't have gas, and water has never been a problem) that is over double the same month's bill from last year will have the overage assigned as a fee.It is important to keep your bookkeeping straight if you do assess a fee.

Solid curtains, water fountain in the backyard, adding trees at the property line nearest the freeway, white noise generators are all other options.

Hot water heaters are tankless and new.

Quote from @Chris Seveney: @Charlene Kingsnorth have you had an sec attorney also review what you are doing as if you're are having multiple people as part of a loan participating in it depending on the state this could get you in hot water - so be careful  good point Chris some state allow fractionalized deed of Trust mortgages other do not or require PPM like documents prior to offering them..

City water with one main at the street and how will they bill. 

Do any of these STR insurance policies cover against fire, water, wind or hail damage.