Lead in Household Water

Table of Contents

• Introduction
• Sources of Lead in Household Water
• Effects
• Testing for Lead
• Reducing Exposure to Lead
• Treatment
• Alternative Home Plumbing Materials

Introduction

People are exposed to lead from a variety of sources. In Virginia there are negligible amounts of lead in surface water and groundwater, but the water in household plumbing systems can contain high levels of lead. Because lead is a serious health hazard, it is very important to reduce lead contamination of drinking water.

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Sources of Lead In Household Water

If your plumbing was installed before 1930, it probably contains lead pipes. Since then copper pipes have largely replaced lead pipes, but lead solder is still commonly used.

In many cases, lead levels decrease as a building ages because mineral deposits from the water coat the inside walls of pipes, providing a barrier between the lead and the water. However, water with very low pH is too corrosive to deposit this protective coating, or scale. Instead, corrosive water will dissolve the metal pipe and fittings, depending on the extent of the water's corrosivity, its temperature, and the length of time it is in contact with the lead source.

Shallow groundwater sources are generally more corrosive than deep wells. Soft water enhances dissolving of lead from plumbing because the absence of minerals in soft water tends to make the water more reactive.

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Effects

Lead reacts with enzymes in the body to slow or stop essential physiological reactions. Since lead is accumulated and stored in the bones, continued exposure to it will severely affect our health. When lead levels become so high that they saturate the bones, blood lead levels begin to affect nerve tissue.

Fetuses, infants, and young children are particularly vulnerable to lead poisoning. Doses of lead that might have little effect on adults can severely affect small bodies. Also growing children rapidly absorb any lead they consume. A child's mental and physical development can be irreversibly stunted by over-exposure to lead.

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Testing for Lead

The current drinking water standard for lead is 0.05 milligrams per liter (or 50 parts per billion in water). The only sure way to determine if your water contains too much lead is to have it tested. You should be particularly suspicious and pursue testing if your home has lead pipes (lead is a dull-gray metal that is so soft you can easily scratch it with a house key), and/or there are signs of corrosion in the plumbing system (frequent leaks, rust colored water, or stained dishes or laundry).

Water samples can be analyzed for lead content at a certified water testing laboratory. For more information about the location of these laboratories, contact the local Cooperative Extension office or county health department. To evaluate the highest levels of lead present, you should take a sample from the tap after water has been held in the pipes for several hours or overnight. A second sample, taken after the water has flowed from the tap for four or five minutes, will show if flushing the line substantially decreases lead content. For reliable results, carefully follow the laboratory's instructions when you collect each water sample.

The water should also be tested for pH and corrosivity. A pH below the recommended standard of 6.5 indicates the water is acidic enough to corrode plumbing systems.

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Reducing Exposure to Lead

If tests confirm that drinking water contains too much lead, avoid consuming water that has been in contact with the plumbing for more than six hours. Let the cold tap water run for four or five minutes before you drink it or use it for cooking. Use only cold water for preparing baby formula and cooking. Hot water dissolves more lead from pipes. Bottled water is an alternative to tap water.

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Treatment

The first step in limiting lead in drinking water may be to neutralize acidic water by using a soda or phosphate feeder or a tank that contains lime. High or persistent lead levels in drinking water can be reduced by reverse osmosis (RO) or distillation treatment. These methods also will remove a high percentage of other impurities from drinking water.

Ordinary carbon and mechanical filters are not designed to remove lead. If lead is a problem in your plumbing system, do not connect water softeners to pipes leading to drinking water taps. All water treatment devices must have proper maintenance to achieve effective lead removal.

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Alternative Home Plumbing Materials

The June 1986 amendments to the federal Safe Drinking Water Act banned the use of any pipe or pipe fitting with more than 8% lead and any solder or flux with more than 0.2% lead in public drinking water supply systems, residences, and other buildings connected to a public drinking water system. Furthermore, the Virginia uniform building code prohibits the use of lead pipe and solder in plumbing in all new home construction.

Such alternative products as tin/antimony (95/5%) or tin/ silver (96/4%) can be used for solder in home plumbing systems. Both materials have been shown to be more resistant than lead solder to the dissolving action of corrosive water. Plastic piping, if allowed by local building codes, should also be considered as an alternative.

Publication #: 356-483

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