For something that is colorless, odorless, shapeless and pretty much tasteless, water can be awfully noisy.
Even the smallest water noise -- a dripping faucet, for instance -- can sound like a jackhammer in an otherwise quiet house. And when water teams up with air in a confined space, it can sound like "The Anvil Chorus."
Old houses often have one or more of these watery sprites. If you can pinpoint it (and it isn't always that easy), the solution may be fairly simple.
Banging pipes are a common water-noise problem. It's called "water hammer," and it occurs because water moves through the pipes under pressure. When you turn off a faucet or an appliance, the closing of the valve stops the water suddenly, and the trapped pressure can make the pipe shake and bang against a support, a joist or even another pipe. Pipes also may bang if they're not secured properly; the simplest fix is to track down the banging and make sure the pipe is tightly secured. You also can install a bit of rubber or felt as padding.
However, a noise that's more a ticking than a banging may mean the pipe is too tightly secured; figure out which pipe it is and feel along it for a tight place. Loosen the fastenings slightly, or add felt or rubber padding around the pipe.
If the simple fixes don't work, add what's called a water-hammer arrester. It's basically a small chamber that provides another place for water to go when the valve shuts off. It can be as simple as an extra piece of pipe or coil of piping, or as complicated as a ball-type with a diaphragm inside. The devices are not hard to install for a reasonably handy home plumber, although it may require cutting into the wall and doing some soldering. If you're repiping a house in the course of a remodeling or rehab, that's a good time to install water-hammer arresters. It can be done with the plumbing rough-in. Check with your plumber; you may want to write installation of arresters into your plumbing specifications.
During construction it's also a good time to insulate drain pipes that might be noisy with water running through them. Plastic drains are notoriously loud. While the walls are still open, wrap all plastic drains with fiberglass batt insulation, tape it with good-quality duct tape, and fasten it even more securely with plastic ties or metal clamps.
(Pipe insulation isn't enough to protect a pipe in an exterior wall. You still need insulation between the pipe and cold air. The pipe insulation will deaden sound, but you still need to insulate the wall behind the pipe.)
Another annoying water noise that may have a simple solution is whistling; often it occurs because valves aren't open all the way, and the flow of water is restricted. That often happens in new construction, but if the valves have been turned off -- during a rehab, for instance -- they may not have been turned back on completely.
However, whistling can also be caused by water pressure that's too high. The solution, which probably requires a plumber, is to install a pressure-reducing device. (Before you call a plumber, check with your neighbors to see if they have had pressure problems that required installing a reducing valve and ask them if it solved the problem.)
Problems with water-running noises, whether they're drips or constant running sounds, occur at faucets and in toilets usually because some part has worn out.
If you can identify the make and model of the dripping faucet or leaking toilet, you may be able to buy a kit and replace the offending part or parts. Sometimes the replacement is simple. It could be that the flapper covering the toilet tank drain may be loose and letting water run into the bowl constantly. If the problem is more complicated, there are toilet-tank repair kits on the market for replacing all the innards.
Brand-specific faucet repair kits will contain a complete set of replacement parts and often the little tool that loosens and tightens the faucet setscrew so you can get inside. Some tub faucets and shower mechanisms also have repair kits.
Finally, gurgling noises in drains usually mean they have become clogged. If simple cleaning doesn't solve the problem, the fixture may not be properly vented. If you're rehabbing, you can install the vents easily, but tearing into existing bathroom or kitchen walls just to fix a gurgle may be an expensive solution.
For all sorts of reasons -- the environment, the amount of a water bill -- you shouldn't allow your house to waste water. But you may not be able to get every single drip or clank or gurgle, especially in an old house. Try to think of tiny noises as charming; after all, when you can identify every single one, that's when you know the house is yours.
Next: The rehab learning curve.