A half bathroom consists of simply a sink and a WC/toilet, and is ideal for houses with more than 3 people living in them and only one common bathroom. A half bathroom also takes up very little space, and you can plumb a new half bathroom by yourself.
Decide the Location of Sink, Toilet and Other Utilities
Find a corner of your house where you can best fit a half bathroom. If space is a constraint, you can even fit it into a 3’ x 3’ space. Where ever you locate it, try to keep it as close to the main drainage pipe as possible. As a rule of thumb, shorter pipes lead to lesser hassles during plumbing. Once the location is decided, figure out how you want to locate the sink and toilet. You can have them facing each other, on the same wall, or on adjacent walls. Make sure you make provision for taps and drain outlets at all the correct places.
Sketch the Plumbing
Start by making a comprehensive sketch of how the plumbing will go. If your main lines are hidden and you have no clue where they are, you might have to call in a plumber to help you figure out where the pipes are located. You will also have to keep track of any barriers you might encounter such as iron support within the walls.
Cast Iron or PVC?
A major decision is to be made at this point: should you use cast iron pipes or PVC pipes? Cast iron pipes are not known to have any major advantage over PVC pipes when it comes to domestic usage. PVC also gives you a cost advantage besides being easier to cut as per your requirements. PVC is suggested.
Plumbing the Half Bathroom Drainage
If you are inexperienced at plumbing, start by dry-fitting the plumbing system i.e. without any glue to hold the pipes together. The point here is to ensure that your sketch is feasible. If you have performed plumbing before, you might not need to test the system. Once you have the basic layout, start fitting the pipes in properly. It is recommended that you start from the point furthest from the main drain pipe. If you are using PVC primer, take care to wear a respirator with an organic vapor cartridge, especially if the area is not properly ventilated.
Time for Some Water
Don’t forget to turn off the main valve first in case your house gets flooded. Cut into the water supply line at its nearest point and using proper joints pull out a feed to the toilet and sink.
Are You Done? Not Quite
Once you have all the pipes in place it is time to test them. Get professional testing equipment to test for leaks in the supply pipe and drainage system. After all you don’t want your half bath flooded, least of all with sewage.
Now for the finishing touches
The plumbing part is done, now all you need to do is go ahead and put in the toilet and sink, and you will have a stylish new half bathroom.