Of the two types of whole-house water filters, backwash filters have a reputation for being the most cost-effective. Low-maintenance, they guarantee a cleaner water supply throughout your home.
But how do whole-house backwashing filters work? How are they different than cartridge filters, and will they fix your water quality problems? Join us as we solve these mysteries and more, covering everything you need to know about backwash water filters.
What Is a Whole-House Backwash Filter?
There are two types of whole-house water filters — cartridge filters and backwash filters. Both improve your water quality home-wide, but they work differently.
A cartridge filter relies on one or more disposable filters to remove waterborne contaminants. Multistage systems may contain sediment filters, catalytic carbon cartridges, reverse osmosis membranes, water conditioners and more. Changed at frequent intervals, each individual filter requires separate maintenance.
Backwashing filters are different. Like water softeners, they’re single tanks packed with filtration media. They can target a single substance or do the job of multiple filters, from reducing chemical contaminants to sediment removal.
How Do Whole-House Backwash Filters Work?
Unlike cartridge filters, backwash systems are self-cleaning. Untreated water flows through a riser tube into a filter media bed that removes contaminants.
Backwash filters are like water softeners. Equipped with an electronic head, they initiate a scheduled regeneration cycle that sends water flowing backward through the filter to cleanse the filter medium. Contaminants go down the drain, and only treated water flows from your taps.
The backwash cycle is automated, refreshing the filter bed as often as necessary to maintain peak filtration capability. An electronic control valve does all the work, but the backwash frequency is up to you. You can change it anytime.
What’s the Purpose of Backwashing Filter Media?
The purpose of backwashing is three-fold.
It flushes out contaminants, from fine sediment and chlorine to iron and heavy metals, renewing the media’s filtration capacity.
Backwashing also removes organic contaminants, such as algae, and prevents bacterial growth within the media bed and your plumbing fixtures.
And if you don’t backwash filter media often enough, you’ll notice a water pressure drop at the tap as it loses efficiency. Regular backwashing keeps your water filter system clean and guarantees a brisk shower.
Do Backwash Filters Require a Drain?
The majority do, but there are some tank-style filters that don’t. These filtration systems use upflow technology to consistently agitate the filter media so that it absorbs large volumes of contaminants without needing mechanical backwashing.
Limited in capability, however, whether they can accurately be called backwash filters is up for debate.
Types of Whole-House Backwashing Filters
Not all filters target all substances, so like multistage cartridge filters, backwashing filters can utilize more than one type of filtration media or be combined with other types of filters for broader contaminant removal.
Based on the results of a water test, you’ll likely need one or more of these:
Backwashing filters reduce fine sediment, but most manufacturers recommend a sediment prefilter cartridge to remove suspended solids unless your filter is equipped with anthracite, Micro-Z media or Filter Ag. Low-cost, Filter Ag is the most widely used for sediment removal.
Anthracite is a combination of garnet, sand and minerals that trap large particles of dirt and rust as water flows through the mineral tank. Granular, it can hold large quantities of sediment without reducing water pressure.
Micro-Z is a lightweight filter media produced from zeolite, a porous mineral featuring surface micro-mineral projections that remove up to eight times more sediment than sand.
Granular Activated Carbon
Activated carbon filters remove chlorine, sediment and other chemical contaminants. The best-quality carbon is made of crushed coconut shells.
Catalytic carbon filters are chemically enhanced with iron hydroxide to remove hydrogen sulfide and chloramine, an inexpensive chlorine-alternative. Hydrogen sulfide is the odorous gas that makes water smells like rotten eggs.
KDF media removes a greater proportion of chemicals, chlorine and heavy metals than carbon filters. Antimicrobial, it also prevents bacterial growth within the filter.
Iron Removal Filters
Iron removal filters rely on air or chemicals, like chlorine, to oxidize and remove ferric ion. An ion exchanger, such as a water softener, can remove low levels of ferrous iron, but you’ll need a sediment filter to remove ferric iron first.
Activated alumina targets arsenic and fluoride. It’s safe and does not add aluminum ions to your water.
Bone char is made from burnt animal bones. It’s porous, granular media containing carbon, tricalcium phosphate and calcium carbonate. Like activated alumina, it removes fluoride.
Alkalizing Water Filters
Some types of filter media, especially in iron filters, works better when water is slightly alkaline. If you have an acidic water supply, alkalizing filters add calcium carbonate to the incoming water stream, raising the pH.
How Often Does a Whole-House Water Filter Backwash?
A whole-house filter should be backwashed based on water usage, contaminant levels and the type of filtering media — every three to four days on average.
You can install pressure gauges to monitor the system’s performance if desired. All filters have maximum pressure recommendations. Since backwashing uses fresh water and energy, monitoring pressure may help you pinpoint the sweet spot between backwashing too often or too little.
You may not need to backwash filter media as often if usage is low, but a minimum of weekly backwashing is recommended to avoid the buildup of bacteria in the tank.
Pros and Cons of Backwashing Filter Systems?
A backwashing filter system has pros and cons.
• Backwashing prolongs the life of filtration media, so unlike disposable cartridges that are replaced every few months, backwash filters are economical long-term and need less maintenance. They’re set-it-and-forget-it systems.
• They’re also versatile. Different media can be layered to remove more contaminants, including some that cartridge filters can’t handle, like iron.
• Water flow rates are brisk and rarely cause a pressure drop at the tap.
• A whole-house backwashing filter requires electricity to operate and will add to your power bill.
• It also saves money in the long run but costs more upfront than a cartridge filter.
• Backwashing wastes gallons of fresh water — a problem in drought areas. But backwash water can be repurposed for the garden or washing the car.
• City water supplies offer enough incoming pressure to support backwash flow rate requirements. But wells with low flow rates may not provide enough water to adequately backwash filter media.
Always review the technical specifications before selecting water treatment equipment.
Are Whole-House Backwashing Filters Easy to Install?
Installing a whole-house water filter is straightforward. Most homeowners can do it in a day with limited DIY skills. The hardest part for most people is setting the control valve.
First, you’ll plumb-in the filter and add the drain line. Next, you’ll attach the electronic head and plug in it. Following the instructions in the owner’s manual, you’ll set the backwash valve to the treatment position, program the backwash filter cycle, and then give yourself a round of applause for a job well done.
What Do Whole-House Water Filters Cost?
The cost of a whole-house filter depends on:
The Control Valve
Electronic control valves vary in cost. Name brands, like Fleck, have a strong track record for reliability. Look for models with a least a five-year warranty on electronic components.
The Type of Filtering Media
The more advanced the media, the more most filters cost. Catalytic carbon media, for example, costs more than granular activated carbon, and specialized media, like KDF and Micro-Z, will set you back more.
The Size of the System
Filtration media is measured by the cubic foot. A filter containing three cubic feet of media will naturally cost more than a one cubic foot system.
The Quality of the Components
Metal valves, and oversized ports that offer a higher-than-average water flow rate add to the price of a filter but are worth the investment for their durability and performance.
Some systems include a separate sediment filter cartridge. And chlorinating iron filters may come with a carbon post-filter to eliminate unwanted residual tastes.
They’re nice extras, but both will add to the price of your system. If you’re replacing an existing whole-house filter and already have a sediment filter or carbon post-filter, you might save money by choosing a model without them.
Plan to spend $900-$2500 for a high-quality system and add 50-percent for professional installation.
When water quality counts, the type of filtration system you install is less important than the contaminants it reduces. But if high maintenance is all that stands between you and the water you deserve, a whole-house backwashing filter may be the solution you’ve been looking for.