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WATER PUMPS, TANKS, TESTS, WELLS, REPAIRS
WATER CONTAMINANT LEVELS
WATER HAMMER NOISE DIAGNOSE & CURE
WATER ODORS, CAUSE CURE
WATER PUMP REPAIR GUIDE
WATER PRESSURE LOSS DIAGNOSIS & REPAIR
WATER PUMP SHORT CYCLING
WATER SOFTENERS & CONDITIONERS
WATER TANK REPAIR PROCEDURES
WATER TANK: USES, TROUBLESHOOTING
WATER TESTS, CONTAMINANTS, TREATMENT
WATER TREATMENT EQUIPMENT CHOICES
WELLS CISTERNS & SPRINGS
WELL FLOW RATE
WELL WATER PRESSURE DIAGNOSIS
WELL YIELD IMPROVEMENT
WINTERIZE A BUILDING
Water filters: this article describes different types water filters used for drinking water purification both as portable filters and where installed on building water supply systems, including both municipal water supplies and private well water systems. The filters described here are usually intended to improve aesthetic issues in home water supply such as removing debris particles, sediment or odors.
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Types of Drinking Water Filters
Cartridge Type Water Filters
Water is passed through a filter cartridge that is usually contained in a plastic or metal canister. Both portable and permanently-installed water filters are widely available and form the most common water filter system found in residential installations where sediment, odors, or chlorine residue are a concern.
The sketch at left illustrates the water filter element and the path of water passing through it.
Watch out: most conventional cartridge-type water "filters" such as the filter cartridges shown at left are not water purifiers. Only a filter that is certified to remove adequate levels of bacterial contamination are permitted to be sold as water "purifiers". Typically a filter that functions as a water purifier will be a ceramic device.
Ceramic water filter-purifiers, including hand-held portable units capable of removing bacteria, cysts, cryptosporidium, sediment, and other water contaminants are discussed in detail at CERAMIC FILTERS & Water Purification. We recommend that you review independent water filter performance or water purifier performance test reports before relying on a water filter/purifier for the production of safe drinking water.
Watch out: the functions performed by any cartridge type water filter depend on the material from which the cartridge is made. And many home water filter canisters will accept a variety of filter cartridge types intended for varying purposes.
Be sure to read the properties of the filter cartridge you are buying and select a filter cartridge type that performs the functions required. For example a water filter designed to reduce sediment may work well for that purpose but may be ineffective at removing odors.
Hooking Up a Cartridge Type Home Water Filter - typical plumbing connections
As the water filter parts sketch at left shows, a cartridge type water filter is installed in-line in the main water supply pipe after the water pressure tank and before the cold water line branches off to hot water or other destinations. Shown in the schematic is a standard-sized whole house water filter from Aqua Pure (3M) type AP11T. 
You might want to install the water filter downstream of your piping that feeds outside faucets used to water the lawn or wash cars, as you probably don't need to filter that water stream.
The sketch shown at left is the simplest installation, showing a single shutoff ball-valve on the inlet side of the water filter.
Notice that most water filters are installed with the cartridge/canister pointing "down". The filter would work in other positions but only in this down-position can you unscrew and remove the filter base to change the cartridge while avoiding spilling an unnecessary dose of dirty water on your floor.
Most water filters including the water filter shown at left include a shutoff or bypass built into the filter head. The water filter shown at left was installed ahead of a UV light water treatment system. In that location the water filter helps keep the UV light bulb clean and improves the both the level of UV treatment (for bacteria) and reduces the frequency of the need to change-out or clean the UV bulb.
You can see the plastic water filter body wrench in our photo (yellow arrow). We hang this tool near the filter where it won't get lost.
With the filter "off" or on "bypass" you can unscrew the plastic filter base to change the filter cartridge without having to use other water shutoff valves. But we like to install the water filter with more options, as shown in our photo. Most plumbers will install two shutoff valves at the water filter:
Shutting Off the Whole House Water Filter - by Valves or the built-in Bypass/Off Control
Closing both of these valves allows complete removal of the whole water filter assembly without spilling water from the building piping and water supply system should the filter assembly need to be changed out.
A third shutoff valve on a bypass loop that can, if this valve is opened, completely bypass the whole water filter installation. This plumbing bypass around the water filter is handy if the unit is damaged, leaky and needs complete replacement.
To make it easy to change the water filter cartridge most water filters include a built-in shutoff-valve in the plastic filter body top - the red arrow in our photo above and marked by the blue tape in our photo of a Sears whole house cartridge type water filter (photo at left).
This handle rotates to 90 degrees from the position shown in order to turn off water at the filter entry port. Now the cartridge base can be unscrewed, cleaned, and a new filter cartridge installed.
Watch out: Take care when installing the new water filter cartridge that you hold the canister and cartridge upright and that the cartridge is properly seated in the bottom of the canister and that it seats centered in the filter top to which the canister is screwed. If you let the filter flop over to one side during installation the assembly may not filter water and it may even leak.
We like to note the date that the filter cartridge was installed - in the photo we just stuck a piece of blue masking tape on the filter shutoff handle and wrote down the filter cartridge installation date. Then when your water pressure falls to nil and you go to change out the filter cartridge you can embarrass yourself by noting how ridiculously long you'd left the old filter cartridge in place.
Brands of Water Filters used for Drinking Water Treatment
Above at WATER FILTERS we discuss the installation and use of water filters on private water supply systems, a portion of our review of WATER TREATMENT EQUIPMENT CHOICES. Also see WATER ODORS, CAUSE CURE.
Just below we provide the most comprehensive list of water filter and replacement water filter cartridge brands we have been able to find. CONTACT us to add to this list. These water filter products are available from building suppliers, plumbing suppliers, hardware stores, and on-line.
Purchases: With the exception of links to recommended books at Amazon.com who pays us a microscopic commission on book sales, we do not sell anything. Please do not call or write asking to buy something.
American Plumber Replacement Filters American Plumber Filters
Frequently Asked Questions (FAQs)
Questions & answers or comments about choosing and using all types of portable or installed water filters
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Technical Reviewers & References
Related Topics, found near the top of this page suggest articles closely related to this one.