KITCHEN & BATHROOM PLUMBING
YOUR HOME'S PLUMBING
Domestic plumbing consists of three basic systems: supply lines, fixtures and drainpipes. Although it may appear a random puzzle of pipes and fittings, the system and its various components work in a logical way.
The supply system is made up of pipes, fittings and valves that carry potable water throughout the house. Water enters your property under pressure from a reservoir, municipal water system or, in rural areas, from the pump-and-tank system of a private well. Typically, the water passes through a curb valve near the street (owned by the water utility), a water meter and the main shutoff valve. The meter is usually on the street side of the house, and the pipe enters a basement, crawlspace or, if your house is built on a slab, a utility center. Water pressure in the supply lines ranges from 35 to 100 pounds per square inch; the ideal pressure is 40-50 psi. Lower pressure may cause insufficient flow at fixtures; higher pressure may encourage water hammer or burst pipes.
From the cold water main, one supply pipe branches off to the water heater to begin a second, parallel run called the hot water main. From there, secondary branches of hot and cold water spaced about 6 inches apart snake through walls and ceilings to the various fixtures. In a well-designed system, each branch contains a shutoff valve near the point where it leaves the main line. Thus you can turn off an individual run without cutting off water to the entire house.
Plumbing fixtures include sinks, bathtubs, showers, toilets, sprinkler systems and appliances that use water and connect either permanently or temporarily to the supply and drainage systems. Not all fixtures need both of the supply lines; a toilet tank has only a cold water line, a dishwasher only a hot one. Once again, in a good system, shutoff valves control each fixture. Behind the wall at most fixtures are air chambers -- capped vertical pipes that trap a column of air to cushion onrushing water when the faucet is turned off. Without an air chamber, an abrupt turn-off might create several hundred pounds of pressure within the supply system and result in water hammer.
The DWV (drain-waste-vent) system is the least visible part of the plumbing system, but the most strictly regulated by plumbing codes. The system is not under pressure, but depends on gravity to carry waste water out of the house. Each fixture is connected to a drainpipe by a P- or S-shaped trap filled with water that prevents harmful sewer gas from entering the home. When a toilet is flushed or a sink emptied, the water in the trap is replaced.
Branch drains lead to a larger vertical pipe called a stack, which drops to the level of the outgoing sewer line, and projects up through the roof to vent sewer gas and maintain atmospheric pressure in the system. (Larger dwellings may have two or more stacks.) At ground level (or below if there is a basement), the stack makes a near-45-degree turn to become the main drain, then slopes away from the house to enter a public sewer line or private septic system.
Sink faucets are simple valves that control the flow of thousands of gallons of water each year in the kitchen and bathroom. Faucet trouble usually announces itself as a steady drip, drip, drip from the spout, or as a slow leak from around the handle or collar. To solve the problem, you must first identify what kind of faucet you have so that you can buy the exact replacement parts. In most cases, this means disassembling the faucet, then comparing it to those illustrated in this chapter.
Compression faucets, always double-handle, have a washer that rests on a seat at the bottom of the stem. When a compression faucet is turned on, the washer rises to allow water to flow to the spout. A variation is the reverse-compression faucet; when it is turned on, the stem lowers to create a space between the washer and seat, allowing water up. Refer to the section on compression faucets for repairing both types. Simply changing the stem washer will often stop the spout from dripping. Replacing the O-ring or packing in the stem will usually stop leaks from the handle.
A diaphragm faucet, another type of double-handle faucet, is easily repaired. A change of O-ring stops most leaks from the handle. Replacing the diaphragm, which controls water flow, stops leaks from both the spout and the handle.
A disc faucet, double-handle or single-lever, has a pair of plastic or ceramic discs that move up and down to regulate the volume of water, and rotate to control temperature. The disc assembly rarely needs changing, but the inlet ports can become clogged, and the seals can wear out.
A rotating-ball faucet, another single-lever faucet, employs a slotted plastic or brass ball set atop a pair of spring-loaded rubber seats. The handle rotates the ball to adjust water temperature and flow. When this faucet leaks from the spout, its springs and seats probably need replacing. Seepage around the handle points to worn O-rings or a loose adjusting ring.
A cartridge faucet regulates water flow by means of a cartridge controlled by a single lever. Repairs involve changing the O-rings or replacing the entire cartridge.
Leaks under the sink may be a result of loose connections between the faucet body and the supply plumbing. Refer to the illustrations below and check all locknuts and coupling nuts for snugness, tightening one-half turn where necessary. Leaks around the aerator or a reduced flow from the spout may be caused by an accumulation of sediment on the screen inside. Every few months, unthread the aerator from the spout and brush it clean with a toothbrush and vinegar.
Most modem kitchen sinks are made of stainless steel or enameled steel, with two basins draining into a trap bend that blocks sewer gas from entering the house. A trap ann joins the bend to the drainpipe at the wall. Under a single sink is a one-piece fixed or swivel trap, consisting of a trap bend connected to a trap ann. A dishwasher fits under any sink; its drain hose attaches to an air gap -- a simple device that prevents back-siphonage -- and another hose leads to the garbage disposer or sink tailpiece.
The two problems that most frequently plague kitchen sinks, clogged drains and leaky supply pipes, can be handled with basic plumbing tools. You can avoid clogs altogether by placing strainer baskets in the drain openings and not pouring grease or coffee grounds down the drain. If a sink does back up, a plunger or manual auger will break up most clogs. Use a chemical opener in a porcelain sink if the drain is only partially clogged, but never use chemicals in an enamel or stainless-steel sink; they will mar the finish. More serious blockages can be cleared by opening the trap or by probing the drainpipe behind the wall.
You may only need to tighten a loose slip nut on the drain assembly to stop a leak under a sink. If this doesn't work, remove that part of the trap nearest the leak and install a new washer under the connecting slip nut. Keep an assortment of washers on hand; whenever you disassemble a trap it's wise to replace all the washers.
When you remove part of a trap, you may decide that the piece is too corroded to reinstall. You can replace it with metal, polypropylene or PVC plastic. Because it is light and easy to work with, plastic is especially suited for do-it-yourself plumbing. (If you leave for the plumbing supply store, close the shutoff valves to ensure that the faucet will not be turned on.)
Check that the water under the sink is not leaking from a faulty dishwasher drain hose. If the hose is at fault, turn off power to both the dishwasher and the disposer and close the dishwasher shutoff valve. Then tighten the hose clamps at the disposer and at the a