Hidden Kitchen Systems: Plumbing, Waste and Water Purification
Plumbing Supply Lines
Plumbing lines also come in two types, supply and waste. They are very different in many ways. Supply lines bring hot and cold water into your kitchen from the hot water heater and main water supply line. They are pressurized by water pressure provided by the water authority or, if you use spring or well water, by a pumping system. The fact that these lines are pressurized is important because it determines what they are made of and requires that their installations be done correctly to avoid damaging leaks.
Supply lines are made of copper, plastic or galvanized steel. Galvanized steel lines eventually clog up from mineral deposits and have generally been replaced by copper or plastic which do not. If you own an older home with galvanized supply lines, have them replaced now because they will eventually become useless. You may notice a corresponding increase in water pressure as a result.
The quality standard in supply lines is copper pipe soldered together at joints. In some areas plastic or poly-vinyl-chloride (PVC) supply lines are allowed by code. They are cemented together with a solvent based adhesive which permanently bonds the joint. Given the choice most plumbers will recommend copper for its durability and strength over plastic. In our opinion you should install the best plumbing supply lines you can afford. They should last the life of your house. In many areas building codes still require the use of copper supply lines.
Supply lines must be provided for all sinks, dishwashers, refrigerators with ice makers and any other fixed appliance that uses water. Plumbers have quite a bit of flexibility in running lines because the water pressure will push the water through complex corners and joints with no problem. However, all plumbing occasionally entails drilling holes in wall studs and floors or cutting away framing. By planning your plumbing lines carefully your carpenter can anticipate these needs and built in spaces to run pipe without compromising structural integrity.
Plumbing Waste Lines and Venting
Supply lines are the easy to handle aspect of plumbing. All that water has to go somewhere after it is used and that is down the drain and into the waste water system, eventually finding its way into sewers or a septic system. Waste lines are not under pressure so they do not require the same degree of leak protection as supply lines. Because waste water often contains foreign solids, these pipes are larger, up to six inches in diameter and made of cast iron or plastic, both of which are acceptable in most areas.
Waste lines must have a steady downward flow to drain properly. Without pressure to push the water through the system they rely on gravity to keep things flowing. For this reason they require more planning to travel around obstacles than supply lines. You need a waste line wherever you have a water supply and every waste line must have a curved trap with a small quantity of standing water in it below the drain. This trap keeps sewer gases including methane from flowing up the drains and into the rooms. The trap must either have a removable clean-out access point for unclogging it or be easily disassembled. The main waste lines must also have clean-outs at various points in the system.
Vent Lines
Waste lines do not just go down, they also go up and out of the roof of the building to vent out gases and eliminate suction which could stop drains from draining properly. These vent lines are often overlooked by neophyte designers and amateur plumbers with potentially disastrous results. Every drain must have a corresponding pipe running up through and out to the outside to eliminate suction. A system without a source of outside air can suck water out of traps allowing dangerous sewer gases into the house. These vent lines run in your walls and up to the roof. They branch off of the waste lines at places near the trap. An improperly designed vent system can result in poor drainage and poisonous gases entering the house.
Vents are a major design consideration because they affect your choices in placing sinks and other water using appliances. You cannot simply add a vent line anywhere you want because they must go up to the roof. Most houses use a series of vent stacks placed near baths and kitchens that ascend vertically through the house to the roof. Vents from various place rise up and connect to these stacks.
Venting becomes a particular problem with sinks located in islands and peninsulas where there is not a convenient wall to run your vent pipe into. Because you don’t want a vertical vent pipe running up and out of your island, plumbers have devised complex systems for routing vent pipes off of islands. It is not a job for an amateur and will increase the cost of placing a sink in an island as opposed to against a wall near an existing stack.
Water Purification and Softening
A clean source of pure water is vital to good, healthy cooking. With many areas suffering from poor municipal water quality you should consider installing a water purification system and/or water softener. This is another choice to be made at the planning stage unless you install it in the basement to purify the entire home’s water supply.
