When the flow from a kitchen or bathroom faucet is lower than expected, it's usually because of sediment that has built up somewhere in the water lines of the faucet itself. Usually, the aerator is the culprit, and by unscrewing and cleaning it, you can restore normal pressure. When that doesn't work, it's probably because there are mineral deposits in the water pipes. Back-flushing the water lines is a good way to get rid of them.
You can accomplish this by blocking the faucet aerator, turning off the hot water and allowing cold water to circulate through the water pipes. A dime works well for some aerators, but for others, you need a larger coin, such as a penny, nickel or quarter. In fact, aerator sizes are standardized to match these common coins.
Getting Rid of Calcium Buildup in Hot Water Pipes
The basic procedure for backflushing the hot water supply pipes to a faucet is fairly straightforward. You begin by shutting off the outlet valve on the water heater, opening a hot water faucet as far from the heater as possible. If that faucet has an aerator, remove it and leave the hot water open while you complete the procedure.
Returning to the problem faucet, remove the aerator, drop in the coin that best fits and screw the aerator back onto the spout. Now water can't come through the spout, so when you open both the cold and hot water handles, or set the handle of a single-handle faucet in the middle position, cold water will flow through the hot line and exit through the faucet you left open.
Leave the water on for several minutes to give sediment time to flow all the way to the open faucet. When the water from that faucet runs clear, turn off both faucets, unblock the aerator and turn the hot water valve back on. Your problem with calcium buildup in hot water pipes should be solved.
How to Remove a Cache Aerator
Aerators are listed in three standard sizes on the Plumbing Supply website: regular (or quarter-size), junior (or nickel-size) and Tom Thumb (or dime-size). Dime-size aerators are often hidden inside the spout, and you can remove them with pliers. These cache aerators are sometimes loose enough to unscrew by forcing your fingers inside them and turning, which works best if you're wearing rubber gloves. But sometimes, you need a tool to loosen one.
Usually, a plastic, cylindrical aerator removal key comes with any faucet that has a cache aerator. If you can't find yours, you can order one online for less than $10, but you probably don't need it. If you can't remove the aerator with your fingers, you should be able to do it by wedging the jaws of a pair of needle-nose pliers against the sides of the aerator and turning it.
Getting Rid of Sediment in Cold Water Line
Because of the higher temperature, it's more common for hot water pipes to collect sediment than cold water ones. But in homes serviced by wells or with very hard water, anything is possible. You would use the same procedure to flush sentiment in the cold water line, but instead of shutting off the hot water, you need to shut off the main water and use an outside water source, such as a spigot from a neighbor's backyard.
Run a hose from the neighbor's spigot to a cold water spigot in your house (an outdoor one works as well as one in the basement), and screw the hose onto the spigot. Now, cover the aerator at the problem faucet, open both valves and let water run out through a third faucet or spigot. If the third faucet has an aerator, be sure to remove it to allow all of the sediment out of the pipes,