Corrosive water, also known as “aggressive water,” is water that will dissolve materials it comes in contact with. This naturally occurring water condition can become problematic for a homeowner when it dissolves metals from the household plumbing system. Corrosive water can cause nuisance problems, health-related problems, and in some extreme cases, it can lead to holes in metal plumbing systems that may require replacement.
In homes with metal plumbing, corrosive water may dissolve copper and/or lead from the pipes and fixtures. Corrosion of copper pipes can leave obvious bluish-green stains around sinks and bathroom fixtures and it may give the water a metallic taste. Corrosion of lead from plumbing systems is more of a concern to the homeowner since it is a significant health hazard, will leave no visual sign and has no obvious taste or odor in water. Lead was a very common component of solders used in metal plumbing prior to 1991. It is probable that you have lead present in your household plumbing system if you live in a house built prior to 1991 and the plumbing is composed of metal.
In rare cases, corrosive water may also leach vinyl chloride from plumbing that was constructed with inferior plastic. All plastic PVC used in household plumbing should be approved by the National Sanitation Foundation (NSF). A stamp with NSF should be clearly visible on approved plastic plumbing materials. There are several characteristics of water that determine its corrosiveness, including pH, calcium concentration, hardness, water temperature, dissolved solid content, oxygen, and dissolved carbon dioxide or hydrogen sulfide. Corrosive water is most often problematic in areas of the country where groundwater is soft and acidic, but the only true measure is to use a stability or saturation index that determines if the water is corrosive based on the characteristics mentioned above. Use of a water softener may increase water’s corrosiveness by removing calcium and hardness.
Corrosive water itself does not pose a health threat when consumed. However, corrosive water may dissolve enough metals to create water that is unsafe for consumption. In metal plumbing, copper and lead may be a health concern. Copper in drinking water may cause both aesthetic (as mentioned above) and health-related problems. Excess copper in the human body can cause stomach and intestinal distress such as nausea, vomiting, diarrhea and stomach cramps. The lowest level at which these adverse effects occur has not been well defined. People with Wilson’s Disease, a rare genetic disorder, are more sensitive to the effects of copper.
Lead, the more serious of the two metals, has been linked to health effects in both children and adults.
Lead accumulates in the body until it reaches toxic levels. It can be absorbed through the digestive tract and lungs and is carried by the blood throughout the body. The severity of the effects of lead poisoning varies depending on the concentration of lead in the body.
Excess lead in the human body can cause serious damage to the brain, kidneys, nervous system, and red blood cells. A child’s mental and physical development can be irreversibly stunted by lead poisoning. Lead poisoning can contribute to lower IQ levels, shortened attention spans and increased behavior problems. While some effects of lead poisoning may diminish if exposure is reduced, others are irreversible. Young children, infants and fetuses are particularly vulnerable to lead poisoning. Lead in drinking water is not the predominant source of lead poisoning, but it can increase total lead exposure, particularly the exposure of infants who drink baby formulas and juices mixed with contaminated water.
One last health concern associated with corrosive water would be from leaching of vinyl chloride from inferior plastic plumbing. Although this is rare, plastic plumbing that is not NSF approved can leach dangerous levels of vinyl chloride when exposed to corrosive water.
Since corrosive water is not a health concern by itself, the U.S. Environmental Protection Agency (EPA) has only set a secondary drinking water standard that all drinking water be non-corrosive. Corrosiveness tests can be conducted by most state-certified laboratories. Although there is only a secondary drinking water standard for corrosive water, there are primary drinking water standards for the products of corrosive water, primarily copper and lead. Laboratory analysis can determine copper and lead concentrations in drinking water.
There are various methods that can be used to solve corrosive water problems. Some of these methods include replacement of the household plumbing system, water treatment systems that make the water non-corrosive, or reducing/removing the by-products of corrosive water, for example lead and copper.
Since corrosive water dissolves the components of the plumbing system, one way to deal with it is to replace the entire household plumbing system with materials that are resistant to corrosion. NSF-approved plastic pipe is made for drinking water and is resistant to corrosion. This material can be used to replace metal plumbing throughout the home. This is usually the best method to deal with corrosive water if pinhole leaks are developing.
Another method to deal with corrosive water is to install a treatment system that will make the drinking water non-corrosive. Units such as acid neutralizing filters or chemical feed systems can be used to reduce corrosiveness of the water by increasing the alkalinity. Corrosive water can be problematic throughout the entire household plumbing system, so these treatment units are usually installed at point of entry (POE) in order to treat all the water that enters the home.
Another treatment method involves use of a chemical feed system that slowly forms a protective coating in the pipe system. The coating keeps water away from the metals and in this way controls corrosion.
One final method to deal with corrosive water is to reduce or eliminate the metals being leached from the plumbing system. It is not uncommon for corrosive water to leach dangerous concentrations of copper and/or lead from the plumbing components but not cause any leaks in the plumbing system. In this instance, removal or reduction of the metals in the drinking water may be the best option for the homeowner.
Since both lead and copper typically accumulate in drinking water as the water sits in contact with the metal plumbing components, a very simple and inexpensive solution is to allow the water to run for at least one minute before consuming it. Flushing the system before use in the morning or after the water has sat motionless in the pipes for several hours will allow the system to draw fresh water that has not had much contact time with the plumbing components. If this is the method used for removal of lead and copper, the homeowner should collect a running water sample and have it analyzed to insure that both contaminants are reduced to safe levels.
If flushing the system does not reduce the levels of copper and/or lead in your water supply, then various treatment systems are available to remove these contaminants in drinking water. Distillation, reverse osmosis, and activated alumina filters are all methods that can be used to reduce and remove these contaminants from drinking water.