Understanding the forces involved in any piping system will help you install one that is not doomed to failure.
An example of when water hammer becomes an issue in outside plumbing is when a large number of sprinkler heads are flowing and the valve is closed quickly. The large number of heads in use increases the flow that contributes to the mass of water being stopped.
Glossary for Pipe
angle stop
A shut off valve. Used for fixtures such as sinks and toilets. 1/4 turn type are ball valve type and generally better. A single outlet port is best. If two supplies are needed it is best to have two separate angle stops, or a double handle / doublestop.
ball valve
A valve who's shut off part is a spherical ball with a passage cut through it. Standard port ball valves have a smaller port thru the ball than the pipe size they are on. Full port ball valves have a full port that matches the inside diameter of the pipe they are sized to. Ball valves turn on and off in 1/4 turn (90°), and provide an unobstructed path for the fluid to flow through.
Building Sewer
The horizontal drain pipe extending from outside the building to the sewage disposal system,(either private or public). 3" Dia. or larger.
Bullet effect
The effect of fresh hot water pushing out water in a hot water pipe only in the center of the pipe or at the top of the pipe due to slow velocity. Thus, allowing the old, cooled-off hot water in the pipe to linger on pipe walls due to friction and gravity, making colder water to drag on the bottom of the pipe, or the fresh hot water to slug through the center of the pipe, allowing cold water to dilute the hotter water. The end result causes a longer wait for full temperature water to reach the faucet drawing the hot water.
Check Valve
A device designed to allow a fluid to flow in one direction only.
Cleanout
An opening or fitting in a pipe to allow cleaning the inside of the pipe. Plumber Snakes are inserted thru a Clean Out. (C/O) is abrev.
If water is flowing out a C/O it is safe to assume the blockage is down stream. The reverse also applies.
dynamic
As used in pressure with water that is flowing. Dynamic pressure is less than static, and lower due to relieving of pressure out discharge point. The more discharge the lower the pressure. No discharge, all pressure is present that exists. As used in pressure measurement the dynamic pressure of a fluid is equal to 1/2 the density x the velocity squared.
FOG
Fats, Oils, Grease. In drain pipes these float to the top of the pipe collect till falling and causing a blockage. Enzymes can digest them and prevent problems if enzymes are used correctly.
P Trap
The J bend and Trap Arm that are under all sinks/showers/drain fixtures. Sole purpose is to trap sewer gasses from venting up from the drain into the room. The P Trap keeps water in it from its shape having a dip or the P on its side to retain water.
Pressure Regulator
A Regulator is commonly used to reduce high pressure coming from the utility line/ Meter. Street pressure is often too high for your house or your landscape piping. Code requires <80psi. Partially closing a valve to reduce pressure does not reduce the water pressure when water is not moving, and therefore Pressures above 80 psi need a pressure regulator to reduce to below 80 psi. Less pressure equals less water use. Conservation requires lower pressures to avoid blown out pipes and excessive water use.
Pro Press
Pro Press is a method of connecting water pipe fittings. pecial fittings are used (Pro Press) and Copper is joined this way without Soldering. I consider this method the best joining method.
PTRV or T&P
Water Heaters need a safety device in the event the heating controls do not stop at set/safe temperature. A temperature and Pressure relief Valve AKA Pressure and Temperature relief Valve is this device. This valve is NOT meant to operate unless to avoid an explosion. When a PTRV is weeping call a professional ASAP.
Push Fit Fitting
"Shark Bite" fittings are an example, they are brass, while JG, or Nibco are Thermal Plastic Push Fit Fittings. These fittings are used to push onto a Copper tube Size pipe or tube PEX or CPVC, or any approved CTS" size tube. These frittings have keeper rings inside to keep the fitting and tube together and no soldering or solvent/glue is used. Instructions come with these fittings , read them. Use them they are good stuff.
Septic/Drain Enzymes
Build up removers, not caustic drain openers are good to use in most all drains having organic waste. The build up of Fats, Oils & Grease (FOG) clog up drain pipes, enzymes reduce this process. Enzymes are used to digest waste in our bodies and out of our bodies. Powdered Enzymes have a shorter shelf life than liquid Enzymes, dont store a long tine, USE THEM.
Bleach and Anti Bacteria Soaps kill Enzymes, they aren't "Green."
thermal expansion
Expansion of water or other materials due to heating. In an enclosed container (such as pipes with no valves open) this will increase the pressure in the container. In water pipes this can lead to leaks, and failures of pipes and fixtures.
TOE Nipple
Threaded, One, End, TOE a nipple having only one end threaded, usually a Sch. 80 Nipple used as an adapter in stead of a Male Adapter. This is a better method of connecting threads to PVC at a Female threaded joint.
Union Fitting
A fitting that is usually 3 parts, one on each side of a nut that connects the other two. The other "two" one each connects to either Pipe and a valve or just pipe on either end. The reason to have a Union is so you can loosen the connecting ring and remove a valve or make free the pipe that would otherwise be bound. A good example of a Union is the swivel on a garden hose, another is not plumbing, but functionally the same, The seat belt latch !or a Vacuum cleaner hose connector.
Water Pressure Regulator
A Regulator is commonly used to reduce high pressure coming from the utility line/ Meter. Street pressure is often too high for your house or your landscape piping. Code requires <80psi. Partially closing a valve to reduce pressure does not reduce the water pressure when water is not moving, and therefore Pressures above 80 psi need a pressure regulator to reduce to below 80 psi. Less pressure less water use, Conservation requires lower pressures to avoid blow out pipes and excessive water use.
A quick and easy repair for low pressure lines. 
A handy method when repair couplings are not avialble or are not large enough to span the pipe damge.
Teflon tape is cheap, lubricates and seals the joint, and is easy to apply...oh wait, except for that last part!
Like most things, if you expect it to work when you really need it to, you've got to to a little maintenance. 
Easily check for leaks you can't even see by using an inexpensive pressure gauge.
Learn about ball, gate, check valves, and butterfly valves, and how to pick the right vavle for a plumbing application.
Dampness is one of the most common problems as a side effect of broken plumbing. Mold can often follow dampness, therefore it's important not to ignore the issue. 
