Aeration Treatment of Private Drinking Water Systems

How Aeration Works:

Aeration treatment consists of passing large amounts of air through water and then venting the air into the atmosphere. The air causes dissolved gases or volatile compounds to be released from the water. In the case of iron and manganese, the air causes these minerals to precipitate out of solution. The water can then pass through a filter to trap the iron and manganese particles.

The air intake for the aerator can be positioned either outside or inside of the home. First identify a clean area for locating the air intake. Avoid areas that have moisture, mold, odor or airborne particles. For inside the home locations, the intake should be at least a foot above the floor, but preferably near the ceiling. If the home is “air-tight” construction, an interior intake location may result in a vacuum being created within the home. This will prevent proper venting of the heating system combustion gases unless a fresh air source is provided.

Typical diffused aeration configuration

Typical packed tower aeration configuration

If the intake is outside of the home, the intake should be high enough to avoid contaminant discharges from the exhaust of automobiles or power equipment such as lawn mowers and leaf blowers but be far enough away from the smoke discharge from a woodstove or furnace. The intake also needs to be positioned away from the waste air discharge location on the aeration treatment system.

At the air intake, you can install an air filter to ensure clean air. Take steps to prevent the entry of animals and insects into the intake air.

Waste air from the aerator needs to be disposed of outside the home. This air is now moist and has a higher concentration of the contaminant removed from the water. The waste air discharge point should be above the eave of the roof. Place the vent away from windows and on the downwind side of the prevailing wind direction. The waste airline should include a manufactured vent cap that prevents the entry of dust, bird droppings, small animals, and other bacterial hazards.

Mist will carry over from the aerator into the waste air vent line and condensation may also occur. Both the intake and waste airline need to be sloped to allow drainage for moisture. The waste air line connections need to be airtight within the home to prevent leakage of hazardous gas.

Effectiveness of Aeration Treatment:

Aeration treatment is effective at removing dissolved gases such as radon, carbon dioxide, and volatile organic compounds, like methyl tert-butyl ether (MTBE) or industrial solvents. Aeration can also be effective at reducing taste and odor concerns from organic compounds. Aeration is also an effective way to precipitate iron and manganese out of the water prior to the metals being removed through a filter system. Aeration raises the pH of water by removing carbon dioxide.

Aeration treatment is not effective against the removal of heavy metals, pathogenic (disease-causing) organisms like bacteria and viruses.

Maintenance

Regardless of the quality of the equipment purchased, it will not perform satisfactorily unless maintained in accordance with the manufacturer’s recommendations for maintenance, cleaning, and part replacement. Keep a logbook to record equipment maintenance and repairs.

Bacterial slime will grow in aerators and storage tanks; therefore, continuous or periodic chlorination will be required. Chlorination may oxidize iron and other metals and cause them to precipitate out, requiring the need for a filter to remove the metal particles.

Adequate ventilation is a must when operating an aeration system. The tank needs occasional cleaning as precipitated sulfur, iron sulfide, rust, and algae collect inside the tank. A valve-controlled drain line to the ground surface makes flushing the storage tank, at least once or twice each year, easier.

Other Considerations

Ensure the system you choose is installed and operated according to the manufacturer’s instructions. After installation, retest both the raw water (prior to treatment) and the treated water at a state certified laboratory to ensure it is working properly and removes the contaminants of concern. You should continue to test the quality of both the raw and treated water annually or more frequently (quarterly or semi-annually) if high levels of contaminants are present in the raw water. Frequent testing will also help you determine how well your treatment system is working and whether maintenance or replacement of components may be necessary.

If there are elevated levels of dissolved iron or manganese in the water, the aeration process can cause rust and other solids to form, staining plumbing fixtures and clothing unless a post-treatment filter is installed to trap the solid forms of iron and manganese. On the other hand, if the raw water coming into the house contains elevated levels of iron and manganese in its solid, precipitate form, a filter may need to be installed before the water enters the aeration system.

The advantage of aeration is that there is no disposal or regeneration of treatment media necessary.

Questions to Ask Before You Buy

Before purchasing a water treatment device, have your water tested at a state certified laboratory to determine the contaminants present. This will help you determine if aeration is an effective treatment method for your situation. Please also review our guidance document Questions to Ask When Purchasing Water Treatment Equipment for more information.

Consumers should inquire about the following before purchasing an aeration system:

• Has the treatment system been tested and certified by a third party to ensure that it meets the manufacturer’s claims?
• What maintenance requirements are there?
• Are there any special installation requirements that may add to the equipment cost, for instance changes to your household plumbing?
• How loud is the air blower? Will soundproofing be required?
• How much electricity does the blower require? Is it energy efficient?
• Check with the State Department of Environmental Protection to determine if any air quality laws may be violated

Product Certification

NSF International is a non-profit organization that sets performance standards for water treatment devices and chemicals. Because companies can make unsubstantiated statements regarding product effectiveness, the consumer must evaluate test results of the device to determine if claims are realistic. Products that have been tested or evaluated by NSF and meet their minimum requirements are entitled to display the NSF listing mark on the products or in advertising literature for products. Manufacturers and models that meet NSF’s standard are included in a list published twice a year. For more information contact NSF at: 800-NSF-Mark or https://www.nsf.org/consumer-resources/drinking-water.