On quite a few inspections, I come across plumbing systems that just can't get a reasonable volume of water to more than one faucet at a time. This is the usual aging pattern of galvanized iron pipe, which was commonly installed in homes between 1900 and 1965. The failure mode is very similar to the arteriosclerosis that happens in our own plumbing systems: minerals coming in with the water react with the iron and zinc inside the pipe to build a plaque-like scale that retards flow. Volume at the faucets gradually diminishes, eventually making it impossible to run two faucets at once. The early results of this are often audible; those screams coming from the shower when someone flushes while someone else is in the shower.

So if you are an old-house owner and your sink is beginning to dribble, what do you do? There are several options: (If you are an old house-owner rather than an old-house owner, dribbling may require other solutions. See your doctor.)

Option A: Replace part of the old galvanized with new galvanized.
Advantages:

1. Not too disruptive, since the work area may be limited to the pipe just downstream from the water heater.
2. May be only a few hundred bucks, and should solve at least part of the problem.

Disadvantages:

1. Threaded pipes require a lot more skill to work with than the newer types. Replacing more than one or two pieces is beyond the capabilities of a home handyman, and even lots of younger plumbers.
2. May not be possible. As the old pipe ages, it weakens. The stresses placed on it by removing parts may cause the remaining parts to crush, split or crack.
3. May not work. In theory, any pipe you replace on the system will improve the flow everywhere downstream from that pipe. Since the scale accumulates faster in the hot water pipes, replacing the pipes just downstream from the water heater should go a long way to alleviating your problems. In practice, this doesn't always work. Sometimes, the trauma of working on the pipe can cause it to "throw a thrombus", (break off a piece of scale that lodges in a restricted pipe further downstream). Flow then goes to zero, as any stroke victim can tell you.
4. If your house is more than 50 years old, those easy replacements may have already been done, and the most serious problem is in the difficult-to-reach pipes inside the walls.

Option B: Replace part of the old pipe with copper.
Advantages:

1. Copper is easier to work with. Any plumber can do it well, and most home handypeople can learn how to use a propane torch to sweat-solder copper.
2. On Detroit city water, scale doesn't build up in copper pipe. No, I don't know why, but this has been my observation on hundreds of inspections of older copper systems. Well water is a whole different ball game; every well has its own unique chemistry, and some can clog up a copper system in 15 years.
3. Should be less expensive that the same amount of galvanized, just because copper is easier to work with.

1. Mixing copper and galvanized can cause lots of nasty corrosion effects. Remember, the old pipe is iron and zinc. The new pipe is copper, with tin-antimony solder. That's five dissimilar metals. Now add the natural electrolytes in the water, and you've got an equation that will drive a chemist to drink! (Of course he has to drink beer, the water doesn't run!)

Option C: Replace all the old pipe with new copper.
Advantages:

1. You're done!
2. Good flow all over, for a long, long time.
3. Good for resale; guys like me will be happy to see a shiny new copper in a house where we expect decrepit iron.

1. Cost. If you have a ranch with an unfinished basement, one bathroom, one kitchen and one laundry, this can be a $1,200 job. Complicating factors in order of increasing expense: Second bathroom. Crawlspace. Finished basement ceiling. 2nd floor bathrooms. A group of these items can run a re-plumb job to 5 figures. Much of that will be for removal and replacement of finished surfaces in order to get at the pipes.

Option D: Replace pipe with plastic pipe.
Advantages:

1. Cutting and gluing plastic pipe is a bit easier than cutting and soldering copper. But only a little.
2. No flames involved. Lots of volatile solvents instead.
3. Materials may be a bit cheaper, but don't assume that. Price some plastic pipe, and also price the fittings, valves, etc. that go with it.

1. Similar cost to copper when all is said and done. You still have to rip out those walls and ceilings to get at the pipe runs.
2. Plastic pipe needs more support, especially on the hot runs.
3. White CPVC is the most popular plastic pipe. The "V" refers to Vinyl, which expands and contracts a lot with temperature changes. Your hot pipes will do a lot of ticking and snapping as they slide past supports with each change.
4. We don't know how long good plastic pipe lasts. (The grey polybutylene has a very short useful life, and should be avoided.)
5. No plastic pipe is allowed within 18 inches of the water heater fittings. You still have to use metal for these runs.
6. We don't have any data on the health effects of the stuff that leaches out of plastic into the water supply. We have some idea what's on that list (mostly oddball metals from the middle of the Periodic Table) but so far there's no research on what it may or may not do to people.

Option C is my personal favorite, but you may prefer one of the others.

Is this a do-it-yourself job? Ask yourself how long your family can live without running water. Like any D-I-Y project, it will take twice as long as you think. Having an understanding neighbor who's willing to share a bathroom can be very helpful, but you may wear out your welcome. Can you run a garden hose from their faucet to your toilet tank?

Hints for the D-I-Y plumber:

• Sketch or photograph everything before you start disassembly. It's never as simple going back together as it was coming apart.
• Make sure that that shut-off valve on the upstream side of the meter actually works. If it doesn't, you won't be able to replace the valve on the downstream side. Often, these valves are so jammed by years of non-use that they won't close, or the stems break off in your hand. The next valve upstream is called the stop box, and it's usually buried in the front lawn. Only the city water department can turn that off, and they may have the same problem with it that you had with the interior valves. Get this equipment working properly before you start.
• If you're soldering copper pipe, you will be using a torch. Keep a wet rag and a fire extinguisher handy.
• If you are doing the whole system, don't bother trying to unthread every fitting. Use a Sawz-all and just cut out as much as you can. This will save half a day's work or more.
• When you start running new copper pipe from the meter, replace the first elbow pointing up with a tee, and place a drain valve on the lower side. This will allow you to drain the system when you find the inevitable leaks. You can't de-solder or re-solder a joint that has water in it. The ability to drain the system from its lowest point is very handy!
• In any house more than a few years old, the cold-water pipe is part of the electrical system, because the main ground wire from the service panel is connected to it. Before you start, have an electrician install an outdoor ground rod, and connect the grounding bus to it. Plumbing can be fun, but you don't want it to be that stimulating!
• One more thing: Before replacing any pipe, remove and clean those little strainers at the business end of each faucet. Accumulated grit in those can simulate a bad system. Cleaning strainers can help restore flow, at no cost at all.

Whatever method you chose, I wish you luck!