Good Morning all! I'm taking a turn opening the home repair shop this week. Please pull up a chair, fill up a mug, and talk about what's going on at your house. The gifted cadre of professionals and amateurs will be happy to answer your questions and point you in the right direction. After the jump, I'll talk a little bit about how water gets to your house, from the basic to the extra-geeky.
One of the hallmarks of a civilized society is access to clean water. So where does the water that comes out of the tap come from, and how does it get to the sink?
If you get your water from a well, it's a pretty straightforward process. A pump brings the water up from the bottom of the well. Somewhere in the process, you might have a water softener and a pressure set. The pressure set maintains the water pressure constant while the pump isn't running, and may boost the pressure even further. From those appliances, the water is plumbed to your fixtures.
A municipal system is larger and more complex, but it has the same basic features. Water is drawn from a source like a river or well, treated to remove all sorts of germs, chlorinated, and fluoridated. The chlorine helps prevent any germs from taking hold in the water after the initial treatment. Fluoridation has a huge impact on reducing dental cavities, in addition to its government-sponsored mind control role (I kid!).
For most municipal systems, reservoirs or water towers provide the constant pressure. For every 2.3 feet above the faucet the reservoir's level is, the water pressure goes up by 1 psi. For a typical minimum water pressure of about 50 psi, the reservoir needs to be about 115 feet above ground level. In hilly cities, the utilities will put the reservoirs at the tops of hills. On flat land, you'll see water towers. If a hill will push the water pressure over about 80-100 psi, the utility will usually install a pressure-reducing valve so the water pressure doesn't damage pipes and fixtures.
From the reservoirs, pipes take the water to individual houses. In modern construction, the pipes will be steel or ductile iron. In the old days, they used all kinds of materials, from the lead of the Roman era to wooden pipes like this one:
This was taken in Mount Rainier National Park, a couple of hours south of Seattle. The pipe is made just like a barrel, with wooden staves that keep the water in, and metal hoops that hold the staves together. In this case, the hoops are a spiral of wire, which is tensioned at bolts at each end of a 10-foot long section. The bump you see in the middle is one of these joints. This pipe ran for at least a couple of miles through the forest. It's a long abandoned testament to longevity of old-growth wood.
As water flows through pipes, it gradually loses pressure. So if you're planning a piping system, how do you keep water flowing well? The most important things are to make the pipes large enough and to minimize the number of fittings. The pressure loss is correlated to the square of the speed through the pipe. So if you double the speed, you quadruple the pressure drop. Just bumping up one pipe size can dramatically reduce pressure losses. Every elbow, union, and especially valve will also give a hit on pressure.
I won't be here right at the beginning, but I'll come by later in the day if you have any questions. All right, that's enough from me. Floor's open! What's on your project list today?