Water follows physical laws based mostly on gravity and pressure. This is the main idea of the science of plumbing. The rest is mostly the exact effects of pressure and gravity on water, and how these factors control its flow. Grasping a basic understanding of how water moves can help you make small repairs or come to recognize the severity of certain plumbing issues. Such knowledge would, no doubt, not only be useful but could save your house and money.
Plumbing systems work in two ways; one is to take water in, and the other is to take water out. In summary, it's clean water in, dirty water out. If that simple order or sequence gets mixed up, it's time to call a plumber to fix a monumental plumbing disaster.
How does clean water come into your home? That is explained by the natural law of pressure. The pressure allows clean water to pass through pipes, travel upwards to one or several floors, move left or right into this room or that, wherever it's needed. Those ubiquitous water valves control the way these pressurized water move in and around your home. Coldwater flows from the primary pipes following the process described above. But if you need hot water, the cold water is first redirected to an installed water heater in your home that warms it up. The heated water then travels along the hot water line that again brings the water to all outlets in the home that requires hot water, like the dishwater, the bathtub, or the shower.
If water intake is simple science, so is water and waste outtake. But often, plumbing problems caused by waste outtake result in more costly repairs than the intake. There is a need for the skilled expertise of certified plumbers, or if you plan to repair it yourself, the right "non-leery" attitude, for obvious reasons.
Dirty waste water, after all, leaves your house following the law of gravity. Wastewater goes downward to the sewer or septic tank, nice and easy. Behind this simple rule is the multitude of vents and traps to keep the process of waste removal possible. Vents allow air to fill drainpipes, precious air that allow wastewater outflow. The S-shaped portions of the pipes underneath the sink drain are traps. Traps perform a crucial role in forcing most of the water through the drainpipe but leaving some to seal the area and prevent sewer gas from backing up.
Plumbing, clearly, is a science. Ignore the science behind it and your home will either be flooded, or you will encounter water damage of varied proportions. Undertaking any plumbing repair, particularly major damages, is best left to the capable hands of plumbers. Some areas have particular local plumbing codes that need to be checked on whether or not a homeowner is allowed to self-repair plumbing problems.
Over time, understanding the science behind plumbing can save you money and help to better know your own home.