I'm not that professional but I think a whole house filter would filter particulates like dirt but not chlorine. for chlorine you might need a reverse osmosis system for a specific drinking water tap to eliminate the taste as it's not practical or efficient to put an RO on the whole house supply. if skin issues from bathing are a problem you might need a softener. sometimes when kids have eczema doctors actually prescribe "bleach baths" where a small amount of chlorine bleach is added to the bath water. also many of the water treatment systems can be rented so maybe just rent it while they are there. regardless, proceed with data. water test, pediatrician diagnosis (if it's legal to ask for, no clue), and a system that is right for the application. sounds like the tenant is willing to help out which is awesome.

Eventually, he shifted his attention to me, and now I receive the same treatment.

The neighbor who is attached is the one and only eye sore on the block. 

@Christina Galdieri I agree with the comments on the window treatment replacement and the floor to be tiled (looks like a small bath of probably 50 or so square feet of floor tile, so shouldn't be too expensive to make it look semi-custom).

I think the correct treatment is for them to report the interest on their personal return if the IRS gets really nit-picky, but I don't forsee it being an issue since the amount is relatively small.

You could try ozone treatment first.

Lenders are still unfortunately tend to be very conservative on the rent-by-room (SRO) type arrangements still - its an area that really could use some better understanding out there but just be careful with expectations because a lot of the treatment of these properties (even if nothing like a old-fashioned "boarding house") can be tough

Ask your accountant to read Regs 1.469 and CCA Memo 202151005.You can have Nonpassive Schedule Es under certain circumstances but it appears he is listing it as passive, therefore creating suspended losses.Here is a previous thread: https://www.biggerpockets.com/forums/530/topics/1056436-clearing-up-confusion-on-tax-treatment-of-short-term-rentals

If you're willing to bend your timeline a little to give yourself the best shot at qualifying for 1031 exchanges and being super tax efficient with your properties, you could try doing the following: - Hold each successive property for at least 12 months before selling - make sure that you acquire property in one tax year and then don't sell that same property until the following tax yearI want to stress that you do not automatically lose out on 1031 treatment by not taking these steps, and similarly you don't automatically qualify for 1031 treatment by simply taking these steps. 

If you are repairing your own property that is an increase in the basis of the property, which will result in better tax treatment when you sell.