Water coming into your home runs through a water meter and then goes into the hot water tank. The cold water runs directly to the plumbing fixtures (the water in your garden hose and toilets is the same as the water in your cold water faucet in your kitchen). The hot water runs from the hot water tank where it is heated and stored until you need it in the house. When you are done with the water at your house, it drains into a waste water pipe that carries the water to the sewer.
A septic system is a large holding tank designed to hold human biological waste until it breaks down into gases, water or solids. Eventually, the gases and water are passed from the tank into the environment, while the solids sink to the bottom of the tank. The solids are removed from the tank by having them pumped out.
There are many reasons why you might experience sewer or septic system problems.
** Sometimes trees are planted too close to the system and the roots from the tree grow into the pipes causing a crack or break.
** Another reason is flooding or extreme rain. Here in the Northwest we experience floods and heavy rainfall every year.
** Sometimes we ask our systems to deal with things they aren't designed to handle. For example: some kitchen wastes, output from dishwashers and washing machines (including soaps and detergents) and objects that are not normally considered "flushable" products.