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Plumbing Systems

By HHI Staff

Water is vital to life, so it should be as healthy as possible. This article covers plumbing and how it impacts the health of occupants. A plumbing supply system carries water into a house, where we drink it, use it for laundering clothes, preparing food, flushing toilets, bathing, etc. Once we are done with the water, a plumbing drain system carries it away from the house to a sewer or septic system.


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All water supplies contain some contaminants, and water can pick up additional contaminants as it passes through municipal water-treatment plants, water mains, supply piping, and fixtures. Water is said to be a universal solvent. This means that virtually anything can be dissolved in it—the good, the bad, and the ugly.

Water supply

The water we use in our houses generally comes from a surface supply (rivers or lakes) or an underground source (a well). Lakes and rivers can be polluted because of agricultural runoff, direct dumping of pollutants by industry, seepage from septic tanks, and spills from sewage-treatment plants. The pollution in the St. Lawrence Seaway is bad enough that beluga whales living there are so loaded with PCBs their bodies are considered hazardous waste. Wells that pull water up from underground reservoirs—known as aquifers—are also often contaminated with toxic chemicals. This is especially common near landfills, or in agricultural areas where herbicides, pesticides, fertilizers, and other chemicals seep down through the soil into the aquifer.


You don’t have to drink water to be affected by it. A major route of exposure to many water-borne chemicals is through the skin while bathing. One study found that up to 70% of the exposure in adults is through the skin. Another study found that an equal amount of contaminants are inhaled when showering. There are fewer chemicals volatilized into the air from bath water than during showering, but an individual may have more prolonged skin contact with the water when bathing. Water supplies that come from wells can also contain radon, which is released into the air as water pours from the tap.


Public water supplies are disinfected to kill harmful microorganisms—usually with chlorine, but sometimes ozone, ultraviolet light, silver, iodine, or bromine are used. Many water utilities also add other chemicals, such as fluoride.


Regulations usually require public water supplies to be disinfected routinely, whether the water needs it or not. Chlorine is a very good disinfectant, but it’s definitely not without risk. When it reacts with dissolved organic material in water, it produces, among other things, chloroform—a known carcinogen. Chloroform is in a chemical family known as trihalomethanes (THMs) which are very commonly found in water supplies. Chlorine can be so bothersome to some people that they cannot even bathe or wash their faces in water containing it—much less drink it. A number of studies have found a link between chlorinated surface water and increased cancer mortality. It’s been estimated that there are 6,500 cases of rectal cancer and 4,200 cases of bladder cancer each year in the U.S. due to chlorinated water. Chlorine can also corrode the inside of galvanized-steel pipes.


Private water supplies, most of which are wells, are often not disinfected at all. So, it’s not surprising that a study done by Cornell University found 63% of rural household water supplies were considered unsafe. A 1988 EPA study found dozens of different pesticides in ground water, 46 of which were attributed to normal agricultural use, and 32 were related to pesticide misuse.


There are three different piping systems in houses—supply lines, drain (waste) lines, and vents. Water enters through the supply lines. After we are done using it, the water passes into the drain lines. These systems must be kept separate to prevent the waste water from contaminating the supply water. The vent lines are actually a part of the drain system. The plumbing pipe sticking out of your roof is a vent pipe. Vents are necessary to allow the wastewater is to flow freely, without gurgling.


Some supply lines can contaminate the water inside them. Above-ground plastic supply lines can also outgas into the air. If drain lines contaminate wastewater, it won’t affect your health—at least immediately. But it could contribute to planetary water pollution because many contaminates are not removed by sewage-treatment plants. Above-ground plastic drain and vent lines can also outgas into the air.

Supply lines

The water mains that carry water to your house can contaminate the water within them. Underground water mains can be made of cast iron, ductile iron, galvanized steel, copper, asbestos cement, or plastic. If a water main is deteriorating—even slightly—contaminants can be transferred to the water supply. Ingesting water containing asbestos fibers released from asbestos-cement water pipes can result in an increased risk of gastrointestinal cancer. Plastic water mains, especially those glued together, can add VOCs to the water. Many people notice a funny plasticky taste when drinking water from a plastic container, evidence that the plastic is contaminating the water.


Sometimes, organic chemicals in the soil can permeate through underground plastic watermains and contaminate the water inside them. This is more of a problem where the ground is seriously contaminated, such as in the vicinity of a gasoline spill.


Private wells often use a pressurized tank to maintain water pressure in the house. Sensitive people tend to be bothered by tanks lined with plastic, or those containing a rubber bladder, more than plain galvanized-steel tanks. In the past, well-casing pipes and the water lines coming into the house were routinely made of metal, but today they are increasingly made of plastic.


There is little you can do about changing underground water mains. And, in most municipalities, some of the mains are so old, few people even know what they are made of. But you can filter the water as soon as it enters your house to remove any contaminates that were there originally, were added at the treatment plant, or were released by the mains.
You have more control of the piping that’s actually inside your house—to a degree. For example, if an existing house has unhealthy piping, it can certainly be removed and replaced. But that can be expensive, time consuming, and disruptive. Pipes are often hidden inside walls, so replacing them means tearing into the walls, then repairing the damage.


While lead pipes are no longer used in new construction, they can still be found in some older houses. The lead can leach out into the water causing ill health. Galvanized steel pipes are much more inert, but they are rarely used today in residential construction because of increased costs. It’s been suggested that some galvanizing processes can impart small amounts of cadmium into the water. In most cases, galvanized pipes are quite inert, but there are rare instances where problems have developed. One woman, after 17 years of investigating, got to the bottom of a health problem related to galvanized piping. She found a dead-end section of galvanized piping in which the galvanized coating had eroded away due to soft-water corrosion. This became a prime place for the growth of filamentous rods, bacterial and fungal spores, decomposing algae, and iron bacteria—all capable of producing toxins which could be aerosolized when water flowed from the tap.


Copper pipes are believed to be quite safe, but one writer has suggested that people can absorb enough copper from drinking water to result in a zinc deficiency. A more-significant problem with copper piping is the fact that the joints and fittings are usually soldered together. Prior to 1986, most solder contained a considerable amount of lead, and that lead could leach into the water. The amount of lead leaching into the water from solder (or lead pipes) depends on several different factors (e.g. the acidity or alkalinity of the water), and there are certainly installations where the lead remains in the solder and does not contaminate the water. Lead leaches into water slowly, so if you run the water for about 15 seconds, you will flush out most of the lead-contaminated water. Then the water drawn off after flushing will contain little lead. In a high-rise building with large-diameter pipes joined with lead-based solder, you may have to run the water for several minutes to flush out the lines. This can waste a great deal water and can be costly.


Another drawback to soldering copper pipe is the fact that the pipe must be coated with flux before soldering. A certain amount of flux can be transferred to the water and it can bother some sensitive people but, in most cases, the flux is eventually flushed out of the lines. In the actual soldering process, plumbers typically heat the pipes with a small gas-fired torch. The burning gas, and the hot solder and flux, release combustion by-products into the air that should be removed from the house quickly with extra ventilation.


In order to eliminate soldering completely in a new installation, flared brass fittings, or brass compression fittings can be used to assemble copper pipe. This tends to be more expensive and more prone to leaks, and it usually isn’t necessary because, today, federal law prohibits the use of lead-based solder in houses. Just to be extra safe, one sensitive individual went so far as to use stainless steel for some plumbing lines—an expensive and extreme measure.


Various kinds of plastic piping are being used more and more to reduce costs. However, sensitive people sometimes complain about water from plastic pipes tasting like plastic. The piping can also outgas slightly into the living space and contaminate the air—especially when used for hot-water lines. PVC plastic has been shown to outgas diethylphthalate, trimethylhexane, aliphatic hydrocarbons, and aromatic hydrocarbons. However, outgassing from hard plastic water lines is usually not significant. (Softer, flexible plastics tend to outgas more than hard plastics because of plasticizer additives.)


The cleaners and glues used with plastic piping are actually much more polluting than the pipe itself—contaminating both water and air. Plumbers who work with glues and solvents regularly are urged to do so with plenty of ventilation. When used indoors, the area should be aired out until the odors dissipate completely. These materials are quite volatile, so they outgas fairly quickly—usually in a matter of hours. However, they can contaminate the water inside the piping for an extended period of time. The water can be turned on and allowed to run for a while to flush out the pipes, but the chemicals will volatilize into the air, so ventilation is again necessary. Another solution is to install an activated-carbon filter to capture any volatilized chemicals in the water.


If the temperature and humidity conditions are right, moisture from the air can condense on cold-water supply lines. This sweating can drip onto surrounding building materials and result in a mold problem. This type of condensation can be prevented by using pipe insulation. If the insulation is bothersome to a sensitive person, it can be wrapped with aluminum foil to minimize outgassing.

Drain lines

The material used for drain lines and vents isn’t nearly as important as that used for supply lines, simply because they do not carry water that will be consumed. Most drains and vents are constructed of cast iron, galvanized steel, copper, or plastic. Plastic lines are considerably less expensive that the alternatives, but they can outgas into the air—primarily from the glues and solvents used to assemble them. However, once the outgassing from the glue dissipates (usually within a few hours), the plastic itself isn’t a significant outgassing source. But it can be bothersome to some sensitive people—especially if they are exposed directly.


There are actually several things that can be done to minimize outgassing from plastic drains and vents. Plastic drain lines that are underground, or cast inside a concrete slab, are well-separated from the living space, so plastic used in those locations is generally not a problem. Plastic drain lines within the house itself, or inside building cavities can be wrapped with aluminum foil to prevent outgassing into the living space. In addition, the plastic pipe can be purchased early in the construction process and allowed to outgas before being installed. If these precautions are taken, plastic piping is often acceptable in a healthy house—particularly for drains and vents.


It’s important that supply lines and drain lines be separated and not interconnected. It they are connected together, the wastewater could easily pollute the supply water. While this doesn’t seem like a strong possibility, there are some situations where it does occur. For example, there is an overflow pipe attached to a temperature-and-pressure relief valve on a water heater that is sometimes connected directly to a drain. While the valve rarely opens, if it does, there can be a direct pathway from the drain into the hot water tank. This is called backflow contamination.


In the case of a water heater, backflow contamination can be prevented by having an air gap between the end of the overflow pipe and the drain itself—something that is required by building codes. Backflow contamination can also occur when lawn chemicals flow backwards into a lawn-sprinkler system, when a hot-water or steam heating system is interconnected with a drinking-water supply, or when someone is unclogging sewer lines with a garden hose. Prevention can be as simple as installing a backflow-prevention valve, available from local plumbing suppliers. Using a garden hose connected to a sprayer containing chemicals can allow the chemicals to travel backwards into the water supply. This can be prevented by attaching the hose to a sillcock fitted with a backflow-prevention device.


In one unusual case, an exterminator was using a client’s garden hose to power his pesticide sprayer. At the same time, the water utility was doing some repair work to a water main. There was a drop in water pressure, and pesticides were pulled backwards into the main. The resulting contamination lead to $60-65 million in lawsuits, and all the plumbing and water-related appliances (refrigerators, washing machines, dishwashers) in 19-20 houses had to be replaced. On a much smaller scale the same type of thing can happen with a kitchen-sink sprayer. If the sprayer is dropped into a sink of dishwater, and there is a drop in water pressure, it might pull dirty water back into the plumbing, which could be deposited into a cup of drinking water a little later.


The brass components used in some faucets can be contaminated slightly with lead. Some manufacturers use plastic components instead to avoid even small amounts of lead. Most faucets contain some plastic or rubber components that can leach into the water that’s directly in contact with them. This leaching is a very slow process, so there isn’t much water that’s actually contaminated. When you turn the water on, if you let it run for a second or two before filling a drinking glass, the small amount of contaminated water will go down the drain.


When sinks and faucets are installed, they are often set into a bed of plumber’s putty. This is to prevent water that gets splashed around the edges from running underneath the sink or faucet. Plumber’s putty has a slight odor, but once a sink or faucet is installed, there is only a very thin line around the perimeter that is exposed to the living space, so it generally isn’t a significant outgassing source. Because more plumber’s putty is exposed at the underside of a sink, it has more potential to outgas downward into a cabinet. If this is bothersome, the underneath side can be covered with aluminum-foil tape. It’s possible to substitute caulking for the plumber’s putty, but this generally isn’t recommended, because the caulking acts as an adhesive, making future removal of the sink or faucet difficult. Plumber’s putty is formulated to remain flexible—and removable.


It simply isn’t possible to eliminate all possible water pollution. Pumps, valves, dielectric fittings, etc. all contain various minor parts that could theoretically contaminate the water. The goal is to eliminate as many contaminants as reasonably possible then, if the water is still a problem for a sensitive person, a filter can be used to 'polish' the water. Occasionally, some very sensitive people must resort to bottled water for drinking and cooking.

Water heaters

Some water heaters can affect water quality, and some can also affect indoor air quality. Installation and operating costs vary, depending on the equipment chosen. In a combo system, a boiler can be used to provide both hot water for domestic use, and hot water for heating the house.


Some water-heater tanks have a plastic lining, but sensitive people generally prefer glass-lined tanks because they tend to be slightly more inert. The insulation, which is between the inner water tank and the outer sheet-metal shell, is either fiberglass or a foam product, both of which can outgas into the room’s air when the tank gets hot. One way to minimize outgassing from either kind of insulation is to set the water heater’s thermostat on high—while increasing the ventilation to the area—to speed up the outgassing rate. After a few days of outgassing, the thermostat can be turned back down to a normal setting.


Many water heaters contain a magnesium anode rod to inhibit corrosion. With some water supplies, the reaction between the water and the rod can result in the hot water having a “rotten egg” odor. This problem can be minimized by filtering the water, choosing a water heater with a plastic liner which doesn’t require an anode, or by removing the anode—something that can shorten the life of the heater.


Solar water heaters can be a healthy option. Most are considered pre-heaters to be used in conjunction with a conventional water heater. There are two basic types of solar water heaters, but there are variations of each. Batch water heaters consist of a water tank mounted outdoors in an insulated box with a glass top. Sunlight warms the water in the tank, then it flows indoors into a conventional water heater to be heated up to a usable temperature. This is the lowest-cost and simplest approach. A flat-plate collector consists of a dark-colored outdoor panel that absorbs heat from the sun and transfers it to a fluid (usually antifreeze) which is pumped to a heat exchanger which, in turn, transfers the heat to the water in a conventional water heater. Some flat-plate collectors, if they are located lower than the water heater, don’t require pumps.


Solar water heaters can be expensive to install—sometimes as much as $4,000. But they tend to be less costly to operate than other water-heating approaches. If you are considering a solar water heater, reducing your consumption should be a priority. This can be done by installing low-flow shower heads, etc. If you use less water, you lower your energy needs, thus the cost of the system. 


The primary health consideration with solar water heating has to do with the potential for leaking antifreeze, but if a system is installed conscientiously, this shouldn’t be a problem.


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Plumbing Systems:  Created on July 8th, 2008.  Last Modified on November 3rd, 2009


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