Timing and Inconvenience
A major overhaul of your plumbing system can present serious inconveniences to your home life. If you are hiring a professional to do the work, schedule it for a time when you will be away from the house or on vacation, if at all possible. Have the work done in the summer months, so that if it requires opening up any exterior walls, you won't subject the house to excessive freezing. If there is no way that you can be away from home for the amount of time the job takes, consult with a plumber about whether it is possible to shut off part of the plumbing system, thus enabling you to use one part of it while the other part is being fixed.
Hiring a Plumber
If you're unskilled in plumbing, or simply lack the time or motivation to do the work yourself, be sure hire a reputable and experienced plumber. Don't be shy about asking for references, and contact several of his prior customers to ask about the quality of his work. Licensed plumbers aren't cheap, but their experience and skills will allow them to complete the job in a much shorter time than if you were to do it yourself.
Shutting off the Water Supply
In most houses, it isn't difficult to shut off the water supply, an act that allows you to work on the plumbing without flooding your home. If you explore your basement or crawl space, you will discover the entrance location of the water pipe. Following this pipe will lead you to a house shutoff that will be located somewhere between the location where the pipe enters the basement and the first interior access point for water. Simply turning this valve or lever will shut off all the water to the house.
Accessing the Pipes
Sometimes the hardest part of plumbing work is getting to the pipes. It will probably require some amount of cutting into the walls, something that may add to the cost and difficulty of the work. As with the plumbing itself, if you're not comfortable with repairing drywall or plaster, you're probably best off hiring a professional to do it quickly and neatly.
Large copper or plastic drain pipes can be cut with a hacksaw or with an electric Sawzall. Cut them so that the face of the cut is perpendicular to the run of the pipe; this makes attachment of new pipes much easier. Smaller copper pipes can be cut with a pipe cutter, which consists of a sharp wheel that is clamped onto the pipe and spun around it until it cuts through the metal. Be sure to mark sinks and toilets so nobody uses them while you're working.
Plastic pipes can be attached using a special adhesive that is designed to seal them together. Copper pipes are attached by soldering them. To solder a pipe, you need to clean the surface using flux, and then heat it with a blowtorch so that the heat of the copper melts the solder. Don't melt the solder directly with the blowtorch; it won't adhere to the copper unless the copper is hot enough to melt it.