It came with an old washer and dryer on my tenants side (which is a 3/1).

I am doing some renovations to one of my units and I am going to be installing a washer and dryer in the unit so they do not have to share with other tenants in the building.

There is no washer drier hook up and there are window AC units. 

Our local wholesaler is a one email solution...I request current availability of a size, type, color and general model to replace an existing unit from the person assigned our account, they send me the detailed specs and cost which includes delivery, remove and dispose of old unit, and any accessories needed such as range pigtail, 3 or 4 prong, or washer hoses, etc.

Question: Do you have to have the washer/dryer in there?

All the units include a washer and dryer.

Rehab #1: 2 bed | 2 bath, 1,180 sq ftUpdated kitchen and both bathrooms; new lighting and paint throughout. 10 week rehab, plus another 2-3 weeks to furnish for STR.Labor: $30kMaterials: $25kFurnishings & Finishes: $12kRehab #2 was the detached SFR: 1 bed | 1 bath, 900 sq ftUpdated flooring, paint & lighting throughout; added washer/dryer; rearranged floor plan; replaced broken water main lineLabor: $28k Materials: $13kFurnishings & Finishes: $5.5k What was the outcome?

Are there washers or anything else that could draw a lot of water?

My wife is also a genius and came up with the idea to rent washer/dryers out for $60 a month and nearly every one  of our tenants do, that makes us 18k extra a year.

Examples would be a 3 bedroom with only a stand up shower, a sink in the pantry, a 3 bedroom, 1 bathroom with the bathroom between the two bedroom and no secondary access, washer/dryer in the kitchen, etc.Laundry - ability to put in hookups in the basement if not possible in the unit itself.