I'd suggest spending some time looking at your water quality/temp and how to control it.
Where I live, the water is so hard that it is just one step below wet concrete. Nasty stuff photographically. I use distilled for most of my alt process stuff because of this. You may want to consider an R/O unit or a softener. Or just having it as an option (ie: do the plumbing so you can just plug one in). It sounds like you are happy with the tap water as it is now, but that can change. Here they switched water supplies and the water got much harder. Always good to have options, and the cost would be a couple of bucks to simply add the connectors.
Temp will be more important to you. Seriously consider plumbing something in for temp control. Even to the point of adding your own heating unit. Running off of the main hot water tank could be a problem if others in the house do something like take a shower or run the dishwasher.
Speaking of heating, also make sure the room you are using won't get too hot or too cold for you. We have one room in my house that is either too cold or too hot (usually the later considering where I live) unless we leave the door wide open. As far as I have been able to tell, this is simply due to the way the heating/cooling system works. Most homes seem to have one room like this. Since leaving the door open is not an option, make sure the room is comfortable. If it isn't figure out how to make it comfortable! You will be sinking some bucks into this, and there is no point in being uncomfortable in it!
Oh, and get the best fan you can. More fan than you think you need is probably the best way to go. I have heard more people say they wish they had gotten a better fan than anything else when it comes to darkrooms.