Learning how to plumb can be very difficult and confusing for most people.  But there are some basics that can help in almost any circumstances.  If you know how to plumb, you can do many simple jobs. If you keep these basics in mind, any do it yourself project can be tackled, to a point.  I have almost always tackled more than I could handle and had to call a plumber when things got difficult.  But, I learned a lot and cut the plumbing bill in half by doing at least part of the job myself.  Here are the basics:

1. Basically, there are two pipes connected to your home.  The first brings in clean water, the second takes away waste water and sewage. The pipe bringing in clean water is pressurized, which is how the water is able to reach the second story of your house.  Water in this pipe is cold, so in order to get hot water, it must pass through to your hot water heater.
2. In some cases, before the water supply splits off to the hot water heater, there will be an additional split between the indoor and outside water supply. I have this in my house. The indoor supply is routed through my water softener and the outdoor supply goes to spigots.
3. Main supply lines are typically 1 to 3/4 inch in diameter, but thee lines that branch off to individual fixtures are smaller, usually ½ inch.  Knowing this will help you at the hardware store.
4. The waste water pipe we talked about in number one, exits the house through a wastewater system. Each sink and toilet is connected to the waste system. The first step in this system is a trap at each fixture. A trap is a U shape and is designed to hold a small amount of water so that toxic sewer gas cannot seep back up through the pipes and into your home.
5. Once water has flowed through the trap, wastewater will pass through a T; here is where it can be complicated. One branch of the “T” goes up and the other goes down. The pipe that goes up will go all the way to the roof to let in air to compensate for the natural vacuum that is created by water going down the other end of the  T. water going down the pipe creates. Think of what happens when you hold your finger over the end of a straw that is full of water, when you release your finger the vacuum is broken and the water flows out. This is like holding your finger on top of a straw which is filled with liquid.  Take your finger off the top, and the liquid lets loose.
6. As the water flows out, it will pass some clean out pipes.  These are just pipes with places to clean out clogged wastewater debris.  Usually the clean outs are a t a 45 degree angle.
7. You need to understand why there are so many different types of pipes in your house. Freshwater systems are typically built with copper tubing, galvanized pipe, PVC or Pex pipe. Generally, copper is the most common for interior piping. Galvanized pipe is in older homes. PVC pipe is not as dependable as copper or galvanized pipe. Systems that only have occasional pressure use PVC. Pex plumbing is the easiest to use, with no need for any soldering.
8. Wastewater typically travels through PVC pipe or cast iron.  PVC is usually used for septic systems, however ABS pipe is the pipes preferred in most new construction because of its low cost and ease of installation. Cast iron pipe is in older and more expensive homes because it is much quieter than PVC.
9. ABS and PVC pipes do not require specialized tools other than glue for joining the pipes and a handsaw
   

   Pex Pipe

   for cutting them. Cast iron pipe however different and requires a snapping tool to break the pipe apart. This is tricky so buy some extra pipe because you will probably have to do it again!  Usually a snapper can be rented at Lowes or Home Depot.