@Calvin Kwan Here is a good article going over the pros and cons of this type of bathtub.

(House built into the side of a down slope mountain.)My helpful neighbors told me that all I had to do was what everyone else does--put a 50 gallon trash can on wheels under the ceiling hole and just empty it in the bath tub down the hall after snow melt or rain events....HMMM nope, I got the permits to cut the parking deck from the house, replace rotten wood in the house and most of the deck and stopped the waterfall. 

1. adding bathtub to master bath(currently there is only a shower, so there will be a separate shower and bathtub)2. converting wood burning fireplace to gas insert fireplace3. fencing the property

-Rough in top floor bathroom drain and vent lines with PVC-Pex piping for hot and cold water lines-Set bathtub along west wall -Tie into existing top floor piping for the following fixtures  - bathtub including tub and shower faucet on south wall  - toilet and vanityBasement-Once you walk into the basement, in the southwest corner there's some pipes-Fix 3 inch and half pipe tapping into 4 inch cast iron main drain

Two bathrooms to be replaced with new bath tubs/showers, vanities, toilets, and cabinets. 

The new NEC 2020 is out and it states (note that it is for "locations that are supplied by single-phase branch circuits rated 150 volts or less to ground are required to have GFCI protection for personnelYou have to check and see if your city/state require NEC 2017 or NEC 2020 or neither (like Phoenix AZ)  but it's good to follow the code anyway.2020 Edition: Section 210.8Dwelling Units 210.8(A)All 125- through 250-volt receptacles in the following locations that are supplied by single-phase branch circuits rated 150 volts or less to ground are required to have GFCI protection for personnel.Bathrooms210.8(A)(1)Garages and accessory buildings210.8(A)(2)Outdoors210.8(A)(3)Crawl Spaces210.8(A)(4)Basements (finished and unfinished)210.8(A)(5)Kitchens210.8(A)(6)Sinks210.8(A)(7)Boathouses210.8(A)(8)Bathtubs or shower stalls210.8(A)(9)Laundry Areas210.8(A)(10)Indoor damp and wet locations210.8(A)(11)Boat Hoist555.9Other Than Dwelling Units 210.8(B)All 125-volt through 250-volt receptacles supplied by single-phase branch circuits rated 150 volts or less to ground, 50 amperes or less, and all receptacles supplied by three-phase branch circuits rated 150 volts or less to ground, 100 amperes or less, installed in the following locations are required to have GFCI protection for personnel.Bathrooms210.8(B)(1)Kitchens or areas with sink and permanent provisions forfood preparation or cooking210.8(B)(2)Rooftops210.8(B)(3)Outdoors210.8(B)(4)Sinks210.8(B)(5)Indoor damp and wet locations210.8(B)(6)Locker rooms w/shower facilities210.8(B)(7)Garages and accessory buildings210.8(B)(8)Crawl spaces — at or below grade210.8(B)(9)Unfinished areas of basements210.8(B)(10)Laundry areas210.8(B)(11)Bathtubs and shower stalls210.8(B)(12)Both Dwelling and Other Than Dwelling UnitsCrawl Space Lighting Outlets210.8(C)Specific Appliances210.8(D)Equipment Requiring Servicing210.8(E) [210.63)Outdoor Outlets210.8(F)Sump Pumps422.5(A)(6)Dishwashers422.5(A)(7)Swimming Pools and Similar Inst.See Article 680* Other GFCI requirements scattered throughout the NEC.

They accidentally find mine out, I didn't rent the illegal unit out, used it for my offices, and they allowed me to make a minor conversion, taking out the kitchen and bathtub, rather than the more radical step of converting it back to an empty basement, removing all the plumbing, partition walls.One problem with legal conversions, in my case, duplexes are built to a different architectural standard.

The bathrooms have the original vanities, lighting, tubs and bathtub tile walls - most of the faucets were changed out along with the toilets when I first moved in but some of the faucets are dingy now.

Here are a few more worries:  a new person in the building only adds to the likelihood of one more body possibly tripping and falling down the steps, or slipping in the bathtub and resulting in an ambulance trip to the ER.So, the added worries are many.

We replaced the shower, bathtub, toilets and repainted.