Backwashing Filters

When you need to quickly and effectively treat all of the water that comes into your home, a whole house backwash filter may be your best option. These large water filters include a tank of filtering media through which water flows. The contaminants are trapped in the media, allowing clean, healthy water to flow through your home's pipes. A backwashing filter is particularly effective at treating specific water problems, such as iron, chlorine, or other chemical contaminants.

A whole house backwash filter treats all of the water that enters your house, removing one or more specific contaminants. What makes a backwashing filter special is that it also includes an electronic control valve that starts a cleaning cycle on a pre-selected schedule. This allows the filtering media to be cleaned and reused, often providing several years of service.

These filters are commonly used in a variety of applications, most involving specific water problems. These filters are effective for treating a number of contaminants, including chlorine, chloramines, fluoride, sulfur, iron, and many others.

How Do Whole House Backwashing Filters Work?

A backwash filter, also called a backwashing filter or a media filter, uses a tank that’s filled with some type of filtering media such as those listed above. Generally speaking, this media is used to remove particles from the water; neutralize the pH of acid water; oxidize iron, sulfur, and other contaminants; and absorb certain chemicals such as chlorine, chloramine, and fluoride. Untreated water flows into the tank and passes through the media, which either removes the contaminants or changes them in some way. Cleaner, better water then can flow into your home and be used by your family.

After a set amount of time, the automatic backwash filter cycle begins. Water flows through the filter media in the opposite direction, a process called a backflush. As the water moves through the system backwards, it pulls out the contaminants that have collected in the media and flushes them away, leaving the filter clean and ready to treat more water. In those systems where the media doesn’t pull out the contaminants, the backwash cycle serves to help prevent the media from being packed down and keeps it in good condition. Ineffective backwashing is one of the main reasons that water treatment filters fail.

Typically, a backwash filter cycle will last for 6 to 15 minutes in a residential application. First, water is forced upwards through the filter bed, causing the media to expand, and as it does, the water carries the particles in suspension to the drain. Backwashing then continues for a pre-programmed specific time as a specific controlled rated (based upon tank size). At the end of the backwash cycle, the upward flow of water is terminated, and the water flows very rapidly downward to re-pack the media bed so that it is ready for the next service cycle.

What Can a Backwash Filter Remove?

Depending on what the filtering media is made of, a backwash water filter can be very effective at removing a number of serious contaminants. Here are just some of the different types of whole house backwashing filter and the problems that they can treat:

• Iron, sulfur, and manganese filters
• Granular activated carbon filters
• Catalytic granular activated carbon filters
• Sediment filters
• Calcite pH neutralizer filters
• Bone char filters

Read on to learn more about how each type of backwash filter works.

Iron, Sulfur, and Manganese Filters

Some backwashing filters are designed to remove iron, manganese, and hydrogen sulfide from tap water. These filters typically include a catalytic carbon filter medium, which means that they may also be able to reduce or many organic compounds and trihalomethanes (THMs), a chemical compound believed to have adverse health effects.

The Fusion backwash filter from US Water Systems is designed to be used with a hydrogen peroxide injection system. Hydrogen peroxide is a powerful oxidizer that interacts with the iron, manganese, and hydrogen sulfide, solidifying them so that they can be filtered out of the water. A simple backwashing-approximately every 2-5 days, initiated by the filter control valve, automatically cleans the bed.

Granular Activated Carbon Filters

US Water automatic backwashing carbon filter systems are specifically designed for applications to remove chlorine, chemicals, and pesticides, or for the de-chlorination of water supplies, such as for foodservice, reverse osmosis pre-treatment, and whole-house filtration. Granular activated carbon (GAC) is a special form of charcoal that is made to have a very high adsorptive surface area. Because it’s excellent at pulling chemicals out of the water and adding nothing back in, it’s one of the few water treatment products that always does some good and adds nothing bad. Not only is granular carbon very effective at removing chlorine, organics, and pesticides, it can also remove detergents, improve taste and odor, and is excellent with sediment removal.

Catalytic Granular Activated Carbon Filters

Whole house water filters with catalytic granular activated carbon are used primarily to remove chlorine and chloramines, although this filter media is also used in US Water’s OXi and Fusion systems. Most people only think about catalytic carbon as a way to remove chloramines from a water supply, which is not surprising given that this filtering media is very good at this task – and better than GAC for chloramine removal. Chloramines are the product of chlorine and ammonia that more and more municipalities are using to disinfect their water. The catalytic carbon acts as a catalyst, causing the chloramines to break down into harmless elements.

Reducing chloramines in water is not the only use for catalytic carbon, however. US Water has used this filtering media for nearly 20 years for the removal of iron, sulfur, and manganese from a water supply. The catalytic carbon (which is made from coconut shells) acts as the catalyst between the iron, sulfur, and/or manganese and an oxidizer (such as oxygen, hydrogen peroxide, or ozone) to eradicate them from the water supply.

Whole House Backwashing Filter For Sediment

Whole house backwashing sediment filters from US Water Systems use an alumina-silicate, crystal mineral material that has surface micro-mineral projections with 0.25 to 10 micron spacing. This means that the media can physically filter and trap the suspended solids in the water stream. Our backwashing filters have a dirt-carrying capacity that is three times the amount that a sand filter has.

In addition, the granules can remove a wide range of colloidal and soluble inorganic metallic contaminants. If you have sand, silt, or solids in your water or your water has a high degree of cloudiness (also called turbidity), then a backwashing sediment filter is the right choice.

pH Neutralizer Filters

These filters work to adjust the pH in your water, changing highly acidic water to neutral or slightly alkaline. pH neutralizing backwash filters from US Water use calcite, a form of calcium carbonate, to raise the pH by adding the hardness mineral back to the water supply. If your pH is below 6.9, calcite can be a very effective form of treatment, and it will help eliminate blue or green stains on your fixtures.

Calcite is a naturally occurring calcium carbonate media. One of the advantages of this mineral is its self-limiting property: when properly applied, it corrects pH only enough to reach a non-corrosive equilibrium. It does not over-correct under normal conditions. Calcite is self-sacrificing, so it has to be replace periodically; our tanks have a convenient fill plug on the side to make it easier.

Bone Char Filters

A backwash filter that uses bone char media can be used to remove fluoride from the water for the whole house. This filtering media is different from activated carbon in that it contains both carbon surface area and hydroxyapatite lattice surface area. Hydroxyapatite is a form of calcium that includes a hydroxide (OH^-) ion that can be replaced easily by fluoride. As a result, this media can be far more effective than regular carbon at removing fluoride from the water.

Bone char is produced from selected grades of aged animal bones for better efficiency. It has been shown to have a high adsorption capacity for a wide range of inorganic and organic contaminants, including heavy metals. This filtering media has also been used in the removal of radioisotopes from water and is especially effective in removing radioactive particles, arsenic, and THMs from the water as well.