Ianto moved to sit down on the toilet lid, not really wanting to stay standing nor feeling all that comfortable standing there watching Sulu. He smiled at Sulu's obvious sense of accomplishment in having gotten the taps working properly. "I see you have," he said, in response. "Well done, there." He wasn't being mean about it, though. He thought it was honestly pretty charming that Sulu was just learning about all of these things that were commonplace in the 21st century. Like tub taps, and radiators, and the sorts. "You're going to turn into a regular old historian, if you keep spending enough time around here in the 21st century," he mused.

As for the tub, though. "I'd say...fill it up three fourth's of the way? There needs to be enough room at the top so that the two of us in there don't displace enough water to make the thing overflow, but. I'd prefer to be able to have it as full as we can get it before that point, so there's more water to soak in, yeah?"