“That?” Cathál glanced at the slate-blue pipe in question, then down at her slate. “Water coolant source for distillation unit 02-367, tap off main section 11-9120, return through 02-3683, automatic flow valve controlled by sector utility server #2, manual cutoff accessible via service panel 02-38.”

“Distillation unit? This isn’t a machinery section.”

“Not that kind of distillation unit. It’s a… personal still.” Seeing her apprentice’s still-confused expression, she continued. “A starshine still.”

“You have those on the plans?”

She looked at him appraisingly. “You’re new-up, aren’t you?”

“First spaceside rotation, yeah. What’s that –”

“Look around you. The hab’s maybe two-thirds, or a little more, plumbing by mass. All kinds. Potable, non-potable, gray, black, steam, rad-hot, loaded, non-aqueous – hell, we’ve got reactor lines in section one circulating liquid sodium. People around here get all kinds of upset when they find a pipe that’s not on the plans, especially if they don’t know what it’s for or what’s in it. So we have an Agreement. We agree to put all the, um, unofficial plumbing on the master plans and hook it into the control systems, and the adminisphere agrees not to bug us about it unless it causes a genuine issue.”

“And it’s still unofficial?”

“Surely. But it’s officially unofficial.”