Turn on Measure, then click two points on the drawing.
Drag to pan, scroll or pinch to zoom, or use the buttons. With the drawing focused, the arrow keys pan, plus and minus zoom, and 0 fits the sheet. Every tag, marker and dimension is a focusable target: press Tab to walk them and Enter to select one.
A plumbing plan carries three separate systems on one drawing, and the only way to read it is to take them one at a time. The faint linework is the architectural background from A-101, screened so it cannot be confused with plumbing work.
System one is gravity: sanitary waste and vent. Waste piping runs below the slab, so it is drawn as a hidden line, and every run carries its nominal size and the letters SAN. Follow it the way water follows it, downhill. Each fixture drops into a branch, the branches collect into the 4 in main under the south band, and the main leaves the building through the south wall to the lateral shown on C-101. Vents are dashed and go the other way, up, because a drain needs air behind the water or the trap seal pulls out. The stack marked VTR carries through the roof. Cleanouts are the small circles with a cross: one at the base of the toilet room branch, one where the main changes direction, and a two way cleanout outside the wall. A cleanout is not decoration, it is the only way anyone will ever rod that line.
System two is pressure: cold and hot water. Cold water enters through the north wall, runs east and west along Corridor 114 above the ceiling, and drops to each fixture group. The heater WH-1 sits in Mechanical 110 and hot water leaves it back along the corridor. Pressure piping does not need slope, so it is drawn as a straight run and sized by flow, not by fall. Sizes step down as the run gives water away, the same way duct sizes do on M-101: 2 in main, 1 in branch to a toilet room, 3/4 in and 1/2 in to a single fixture.
System three is storm: the roof drains and their overflows, shown as symbols on this plan with the note that the piping runs down inside a wall chase.
Now use the schedule. Every fixture on the plan carries a tag, and every tag has one row in the plumbing fixture schedule at the bottom left. The row gives the waste, vent, cold water and hot water connection sizes for that fixture. A tag with no row, or a row with no tag on the plan, is a coordination problem, and finding one is exactly the skill this sheet drills.
Two numbers on this sheet are worth committing to memory because they appear on every plumbing set you will ever open. Gravity waste 3 in and smaller falls a quarter of an inch in every foot of run. And the size written on a pipe is a nominal size, a name for the pipe, not a measurement you can take with a rule across the drawing.