At least, not all of the sinks.
Dupes will still use the sink outside the bathroom. So you can have a 64-tile (16×4) bathroom with as many as 7 lavatories inside, and dupes will still wash their hands after using the toilet if the sinks in the bathroom are busy.
The layout shown here fits within a 25-tile block, which is the same width as a ranch using the door trick. The back half of the ranch can also hold the water sieve, overflow tanks, or even hydroponic tiles if feeding the overflow to reed fiber, so it’s a good way to double up on space usage.
Came back to edit this post to show what it looks like when it’s all in place. Here I’m using a chlorine room to disinfect the overflow (clean) water, before sending it off to my main tank. The valve is set to open when the tank gets 90% full and close again when it’s below 80%. This leaves enough sanitized water in the tank that the incoming germs die off before they can leave the tank.
