Please accept my apology for the delay in getting back to you on this. You can rest assured that I have not been ignoring the questions, in fact, quite the contrary is true. Not only have I been repeatedly looking at this problem, I actually copied the photos and pasted them in my photo editing program where I enlarged them about ten times to get a closer look. Now let me share what I have concluded and see if it corresponds to what you have found. Fact- The house is only 6 years old so all work should conform to the codes that are currently in force. Fact-The T&P valve drain line, Water heater drip pan & HVAC condensate drain line must either terminate outside the structure or discharge into an approved indirect waste receptor. Fact-the T&P drain line may not discharge into the drip pan and the T&P drain line & drip pan drain line MAY NOT be connected to a common drain line. FACT-The T&P drain line, drip pan drain line & HVAC condensate drain line must run "Full Bore" from the source to the point of discharge. From my observation of the photos- The 1-1/2" line extends out from the wall then turns upwards by means of a 1/4 bend with a 3" x 1-1/2" reducer bushing and a short section of 3" pipe that probably was about 4" to 6" high, which would create a waste receptor for the T&P drain & HVAC condensate All of the joint on that section of the line show clear evidence of PVC cleaner/solvent with purple dye. All of that work was probably originally done during the initial "Stack out phase" of the plumbing. At that time the walls would have still been open and the full length of that run would be open for inspection. Now here is my first dilemma. Code expressly prohibits downsizing a DWV line in the direction of flow and that would have immediately caught the inspectors eye. Once the inspector realized that the short section of 3" pipe was intended as a receptor for the T&P drain, Pan drain & HVAC condensate line he/she would have classified that 3" as a fixture and would have then checked closely to see where the 1-1/2" waste arm was discharging. If the 1-1/2" line was connected to the DWV system the inspector would have insisted on a trap under the receptor. The lack of a trap suggests that the line is running to the nearest exterior wall and discharging outdoors, which would not require a trap. There is an extremely remote possibility that they installed a trap in the wall as you suggest, however code only permits a maximum of 15" horizontal offset from the fixture drain opening to the trap input; and it appears that the distance from the 1/4bend to the wall is very close to that length. Why would they put the trap in the wall if it could be much easier attached under the receptor on the end of the line where the 1/4 bend is? It is possible that with the trap on the end of the line it would have exceeded the maximum allowable length from the trap weir to the vent opening for an 1-1/2" line (see my post on "Fixture arm defined") so they installed a trap in the wall and attached the horizontal offset to extend the line, but you said that the drain line in the adjoining bathroom is close therefore this simply defies logic. Now here is the problem at hand. If that line discharges outside the structure as I suspect you cannot attach your water treatment discharge line to that line. On the other hand, if that line is attached to the DWV system you must first determine if there is a trap in the wall because code requires a trap for all fixtures attached to the DWV system. You may not just arbitrarily attach a trap as you suggest because code expressly prohibits "Double trapping" (having two traps in series). In fact, years ago all structures were required to have a "House Trap" on the main sewer line where it attaches to the house main drain, but those traps are now outlawed under the no double trapping rule. Now for the other discrepancies noted: Examine the connections where the T&P discharge line, HVAC condensate line and the water heater drip pan are attached. Note that there is no evidence of purple dye on the joints. This suggests to me that those lines were installed by someone else after the original waste receptor was installed and the individual who made those connections was not familiar with code requirements. Note that the HVAC drain line is a 3/4" PVC line and they attached a 3/4" tee to accept the discharge end of the T&P drain line. That is a code violation. Properly to combine both the HVAC drain and the T&P discharge line that MUST BE a 1" Tee. Under the top tee there is a 3/4"x1" bushing increasing the line to 1" to receive the 1" discharge line from the drip pan. At minimum that tee must be 1-1/4". It also appears that in the process of connecting the drip pan drain line they had to cut the 3" down flush with the reducer on the 1-1/2" quarter bend therefore you no longer have a receptor. Properly the 1-1/2" line should have been a bit lower, but lacking that, the water heater should have been raised up on bricks or other suitable supports to allow vertical clearance for the drip pan line into the receptor. You also stated that the only line visible outside the structure is a cleanout, which is 30' from the building. Code requires that on slab construction the Main Cleanout must be at the junction of the house main drain and house sewer within 3' of the footer wall. I suspect you main cleanout may be slightly covered with dirt and not visible and the cleanout that you found is at a change in direction of the house sewer. Code requires on a house sewer we must have a cleanout at any change of direction which is 45deg or greater and one for every 80 linear 80' of run. As much as I hate to say it, in my humble opinion the only sure way to resolve the issue here would be to make a small opening in the wall and physically see if the line in question is attached to the DWV system and insure whether or not there is a trap. BUT,there is a metal perf strap securing the line to the wood blocking behind the 1/4bend. Code expressly prohibits using metal hangers on plastic pipe. The copper T&P discharge line is discharging into the top of a 3/4" PVC tee from the HVAC condensate line. Under the Tee there is a 3/4"x1" bushing which is enlarging the line to 1" before it enters the 1" tee from the drip pan.

What a nifty project, September. Pictures would be great, Scrappy. To develop that nook and cranny aspect, Rob's layout of facing a desk surface into the stairs sounds good. Depending on how much you'd expect to use it it might be a permanent fixed desk or could be a fold-down surface of some type. You don't mention a file drawer, but one could roll out from under, if desired a partial-width drawer from under a fixed desk against the house's outside wall or full-width set close to floor at the very back of the work surface of either fixed or fold-up. That last would work well if you wanted to keep an open look to your nook by suspending the work surface on a large decoratively curved wood bracket. Depending on your comfort level with the ceiling height, the rear of the desk could potentially set farther back than the post, with the post itself part of the support detail. So, desk to your right as you look in. On the green wall, whatever else you end up doing definitely if possible remove the existing drywall and retrieve up to an additional 3-1/2" of depth, probably 3 or less after finishing, but precious inches added to perhaps 9" of the space already there. Then using those 12" or so, perhaps the bar and other shallow storage on the full height of that wall, the space enclosed with doors below a desk-height counter, open for about 20" above that counter for working and openness, then open shelves above that for storage of anything you wanted. Books? A book shelf or two could also be fitted in along the back of the desk. Back/outside wall--how about wrapping that counter and the closed storage below right on around to the desk? At whatever depth felt good to you. The wall above could hold a single favorite piece of art. To the right of the column, keeping it simple for now, as suggested a single door to storage. Drawers are a possibility, though. Regarding cost--Ikea if anywhere near at all. Their 12" and 24" deep cabinets can be cut down easily to whatever depth is needed, the shelves and rest pop together as an evening project while you watch TV, and they're so inexpensive a mistake is a shrug and try again. But especially for their extremely inexpensive smooth-glide full-extension drawer units of various sizes that hold a great deal of weight and are great for maximizing use of space. Including, if you want, ones that fit into 12"-deep cabinets that are pretty modest in the amount of actual storage space they offer but are still very good for organizing pencils, bottle openers etc. If you could spare 12" on the outside wall, instead of say 8, a row of those could run around both walls under the counter and serve both desk and bar, as well as little household thingies in general. Ikea has a couple of solid-wood doors you might use, but only the slab one lends itself to custom sizing. You might make these yourself. Their solid-wood counters could be used for...counters. Seat--something small but comfy and attractive on wheels with a swivel seat. I'm looking forward to seeing what other ideas are generated and what you end up doing with this nice little space.

I have this weird little space left in my plans that I am trying to squeeze a 4*2 closet and shower/toilet/sink space for my son on the right side (his bedroom is right of my screenshot), a W/D and possibly a 4*1 closet space for vacuum/cleaning supplies, etc. I also need to squeeze in the utility room. We are hoping to find water to put in a well, so I will have a pressure tank, a Geothermal furnace, a radon system, and I am planning to do 2 tankless water heaters and later add a whole home filtration system. Currently, our W/D is in our utility room...and I hate it. This W/D is just for the kid's and guests laundry, but would still prefer side by side units. They were originally planned where the french doors are showing. If I do them off the hallway, I'll do french doors or a barn door (I know, gasp). I love the idea of turning them and having them sort of in a hallway to the utility room...but that makes the utility space really small. I am also trying to keep the exercise room as large as possible. What am I not thinking of that will need to go in the utility space? If I just need enough space on one side for the furnace and the other side for the well pump, then the back wall for water lines, I don't want to devote too much space to the room. I've done some redesign to eliminate both a full bath and a powder room from the basement (kid's rooms are in walkout basement) and moved the guest bedroom to the walkout wall, and gained the exercise room. Now that I have gained so much from the last minute changes, I hate to not make my son's bathroom and closet space perfect...and also don't want to scrimp on the 2nd W/D or make the exercise room smaller than it needs to be to make the utility room larger than it needs to be! I do realize that my HVAC guy does not want to be cramped when working on the HVAC....but am also trying to be realistic about how much space I actually need as I am trying to maximize every last sq inch in the basement.

I like that gray sparkle quartz. I've seen it in person and it's beautiful. try and find a remnant if you don't need that much. if not, look for pre-fab countertops. you can buy a 6' or 8' long piece for under 500. then just get someone to cut it for you Here's one at my stone place in the black sparkle. I love this one too this is a porcelain tile that looks like the cement. easier to care for. they also have a quartz slab that looks like real concrete.