Backwashing carbon filter

Backwashing Whole House Carbon Water Filters

Why do Backwashing Carbon Filters save you money?

Because the GAC carbon is reused over and over for typically 4-5 years. Sediments and rust are periodically flushed down your drain during the “backwash” mode. Set the timer to backwash the carbon every 2-3 days. Backwash every 1-2 days if you have sediments but no sediment prefiltration and you use a lot of water.

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Installation instructions if you have a water softener OR a Chlorine Injection System.

If you have a Water Softener: Installing carbon upstream of a water softener will greatly extend the lifespan of your water softener resin by removing chlorine and organics, both of which will foul softener resin over time and reduce it's service life. Chlorine will turn softener resin into a worthless mush.

If you use Chlorine Injection: Placing a carbon filter after chlorine injection (as far as possible downstream to get sufficient disinfection contact time with chlorine) will reduce chlorine and cancer causing byproducts of chlorine such as Trihalomethanes (THM) and Haloacetic Acids (HAA). For best results a small point of use carbon filter is still recommended at your taps where you obtain your drinking water. This will typically remove 98-99% of any leftover chlorinated organics. Whole house removal of chlorine and chlorine byproducts will significantly reduce your exposure by Inhalation to these chemicals during showering. Showering releases a significant amount of these chemicals (when present) into the air that you breathe, which then instantly get injected into your bloodstream via the process of Inhalation.

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Activated Carbons we may use for your systems:

  • Very Good - Calgon Acid-Washed Bituminous Carbon for good chlorine, taste and odor removal. This premium grade USA-made carbon is better and more expensive than “plain” GAC carbon because the acid wash process removes inorganic impurities from the carbon.
  • Better - Coconut Shell Carbon (vegetable derived) for superior chlorine, VOCs, and chlorinated solvent removal. Produces a sweeter tasting water. Offers better resistance to breakdown from long term backwashing. Has a microporous carbon structure (very small), so is less effective at removing heavier organics with larger molecules.
  • Best - Centaur Catalytic Carbon for outstanding performance in removal of VOCs, chlorine, chlorine byproducts, taste, and odors.
  • Treating Chloramines.  See guideline chart.
  • Treating Dissolved Iron (up to 8 ppm)  See guideline chart.
  • Treating Hydrogen Sulfide (up to 8 ppm) can be accomplished provided you have at least 4 ppm dissolved oxygen in the water.  EBCT is 5 minutes.   See guideline chart. For hydrogen sulfide you need at least twice as many ppm of dissolved oxygen in the water than hydrogen sulfide.  Water can hold no more than 8 ppm of disssolved oxygen even under the best conditions. Extra oxygen can be added to the water with an Air Injection System. 
  • For higher levels of these contaminants, see our Backwashing Oxidation Systems.

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Properly Sizing your Whole House Carbon Filter

Notice: It is critical that you properly size your carbon unit. To do this you will need to accurately determine the Maximum Service Flowrate (in GPM) of your incoming household water service to make sure your unit can properly clean itself during Backwash Mode. You will also need to use the instructions below to determine your Maximum Water Demand/Flowrate (in GPM, not gallons) for your household, to make sure you have enough carbon to properly filter the water being used by several fixtures running all at the same time such as a shower, toilets flushing, 2 running sinks, and laundry machine. Call us if you need assistance or consult your water service professional.

Step 1) For standard Chlorine, Taste, and Odor (CTO) removal, select your carbon unit by first carefully determining your anticipated Maximum Water Demand/Flowrate (in GPM) for your house. You must add up the water demand caused by several of your household's fixtures listed below. This is critical. Undersizing a unit will lead to poor performance. This is measured in Gallons Per Minute.

Approximate Water Demand/Flowrate for Residential Fixtures (Add several of these up): Standard Shower: 3 GPM, Bathtub: 5 GPM, Kitchen Sinks: 2 GPM, Each Toilet: 3 GPM,Dishwasher: 2 GPM, Washing Machine: 2 GPM, Bathroom Sinks: 1 GPM, Garden Hose: 5-10 GPM. Note: for public fixtures these values typically are doubled.

Step 2) Then select a carbon filter system where its stated Maximum Service Flow is greater than the anticipated Maximum Water Demand/Flowrate of your house.

TIP: Carbon works better with (more carbon=larger tank volumes), so you will get better quality water by having the Maximum Service Flow of the carbon filter exceed the Maximum Water Demand/Flowrate of your house by 2 or 3 or 4 GPM. Do not undersize your carbon filter or it will not work properly.

TIP: The Maximum Service Flow values given are for performing “standard dechlorination”, which is relatively easy for carbon to do. For removing extra contaminants and organics (which is more difficult) you will want to subtract several gallons from that (MSF) number – which will put you into a larger sized unit. More carbon means more contact time and more filtration.

Step 3) Make 100% sure that your household water service can meet or exceed the Minimum Required Backwash Rate of the carbon filter you are contemplating. This is absolutely critical to flush out the collected sediments and properly clean the carbon bed. Oversizing a unit so that you cannot deliver the Minimum Required Backwash Flowrate needed by the unit will lead to carbon bed fouling and very poor performance.

If you have high sediment water: If you have a lot of sediments in your water you may precede your carbon filter with a 20 micron (reusable) pleated sediment filter to keep the carbon bed and valves from fouling with sediments and rust. At the very least, use a BB 10” size, but the best performance comes from a BB 20” size, which is considered high performance and creates the lowest pressure drop.

If you also have a water softener or water conditioner: Install the Backwashing Carbon Filter before (upstream of) the water softener to protect the water softener resin beads from chlorine damage. Chlorine will turn softener resin into a mush.

Installation Advice: These are professional products. We recommend having a “qualified installation professional” who has experience with these types of units properly load the carbon, install the unit, and correctly program the control valve for all carbon filters (and water softeners). This will give you the best results, maximize your satisfaction with your fine product, minimize your installation liabilities, and keep you in compliance with your local plumbing codes. Ask your Installation Professional for at least a 30 day guarantee for any call-backs due to leakage or poor performance. Install and use these systems at your own risk.

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Prices are subject to change without notice. 
We reserve the right to change incorrectly priced items.