Routing Pipe and Home Plumbing Configuration
Potable Water Delivered by Pipes, Shut-Off Valves, and Fittings
Oct 8, 2009
The residential water supply system is made up of various metal and plastic components. Generally, these are classified as fittings, valves, and pipes. These water delivery materials have been evolving since the days of the elaborate Roman and the Machu Picchu aqueduct systems.
Types of plumbing materials
- ABS. This is a plastic, once popular, but now restricted.
- Copper. This metal is easy to bend so the use of fittings is minimized. It is very long-lasting but expensive.
- Cast iron. This is a rugged material but can be difficult to work with. It's mainly used for waste drains.
- Galvanized iron. This is the classic. The drawback is that it can corrode over time. A new process called ACE DuraFlow cleans the interior of the pipes and makes them like new by applying an epoxy coating.
- PEX tubing. This polyethylene plumbing component was developed in the 1950s and has outstanding benefits; it remains flexible and stable from below freezing to 200 degrees F (93.3 degrees Celsius) for one thing. This virtually eliminates problems with connectors.
- CPVC. This thermoplastic is reliable, inexpensive, and easy to work with.
The water distribution route
Water is usually delivered to the home from a municipal water system or from a well. As it enters the property, it passes through a meter, which the city or county reads to calculate the water utility bill. Next, it enters the home at ground level. This might be through a basement or crawlspace or by the concrete slab.
Now the line branches off. One side remains cold and the other goes to the hot water heater. For the most part, the cold and hot branches run parallel to each other, although the hot water supply line misses fixtures like toilets that only use cold water.
Controlling and balancing the plumbing configuration
A common rule of thumb is, “the more valves, the better”. Starting with the meter where the city turns service on for new residents, cut-off valves make maintenance easier. Every sink should have one for each supply line, every toilet should have one; even sprinkler irrigation systems benefit.
The pipes by each fixture and appliance should have an air chamber; many local building codes require them. These are vertical capped-off pipes that give the system a shock absorber to absorb the elevated water pressure when the the water is turned off. Otherwise, the result is a water hammer (bang!) or the possibility of a burst pipe.
The drain-waste-vent (DWV) system
This system carries waste out of the home under gravity, not pressure. The first section is a p-trap or s-trap which keeps fetid sewer gas out of the home. All the branch drains line up with and empty into a vertical stack (stink pipe) which vents up through the roof.
The purpose of the stack is to maintain atmospheric pressure on the DWV system. If the stack becomes clogged with an obstruction like a bird nest, a vacuum will be created and odd things will happen. For example, a common toilet problem where the bowl fills properly but then slowly drains out. The vacuum is slowly drawing it out as the system pressure tries to equalize. This has left more than one hapless homeowner perplexed.
That's home plumbing; humble, yet sophisticated.
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