I could never pass biology, but I can apparently pass a plumbing inspection. We recently completed all the rough-in for plumbing drains, vents, and supply lines. Below is a gallery of various parts of the plumbing system.

The supply lines are various diameters of PEX color-coded red and blue for the hot and cold lines. In one of these new systems its common to have a single manifold with “home runs” to each fixture in the house. It makes for easy shut-offs, easy troubleshooting, and faster hot water to many of your fixtures. (That last bit works because in a traditional system the sink at the end of the line has to drain 100 feet of meandering 3/4 inch pipe to get fresh hot water from the heater. In a system like this it just has to drain a tiny 3/8″ tube that runs the shortest distance directly to the sink).

The drain / vent system is honestly far more complicated. Because it operates only under gravity and not by pressure, everything has to carefully slope away toward the city sewer. Nothing can slope the wrong way or you’ll get stagnant water pooling your drain pipes and you could get clogs. If you don’t vent it right you can get glugging, water back-ups, or nasty sewer gasses escaping into your house. Cutting and gluing the pipes is pretty easy, but planning and routing it all can be a head-scratcher. Fortunately I planned out most of the plumbing and HVAC routes well in advance so they are highly economical in pipe lengths, fit easily into planned wall areas and chases, and generally don’t get in each other’s way.

After my initial inspection I did have two findings I had to correct. First off I used some “sanitary tee” shaped drain pipes in an orientation they are not allowed (on their sides as opposed to vertical) and I had several places where it is required to use “long sweep” 90 degree elbows instead of the shorter, tighter normal 90 degree elbows. That meant cutting out already finished drain lines at each of the three bathrooms and some work on the kitchen sink drain.

All-in-all it was about $75 and 7 hours of rework, but that’s not bad. I had no expectation I would get everything right on the first try in a job this big. As of right now it looks like we will save between $7500 and $8000 by doing the plumbing ourselves vs. taking the lowest bidder.

After that bit of re-work Tony the plumber (yes, that’s his real name) reviewed my changes and we passed rough plumbing inspection. On to electrical!