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Certified Water Treatment Devices - Frequently Asked Questions

NOTE: This page and the linked pages below are for historical reference only, due to statutory changes -- for information about the current Residential Water Treatment Device Program, click here.

 Last Update:  September 6, 2011

There are hundreds of California-certified drinking water treatment devices. Carbon filters are the most common type of device, typically sold in the form of counter top, faucet-mount or under counter models. Other types of technologies available include distillation, reverse-osmosis, ion-exchange, ceramic filter, and ultraviolet light. 

When a manufacturer claims that a drinking water treatment device will reduce toxic chemicals or makes other health related performance claims, the device must be certified by the California Department of Public Health (CDPH) [Health & Safety Code Section 116830].


What does California Certification mean?

CDPH certification means that the device has been tested by an independent, state-approved laboratory (1) to verify the manufacturer's health-related performance claims, and (2) to ensure that materials within the device do not add contaminants to the treated water. 

CDPH certifies devices for specific health claims such as:

  • "Reduces THMs, 2,4-D, DBCP, lindane, TCE, PCE" (examples of organic chemicals)
  • "Reduces lead, copper, mercury" (examples of heavy metals)
  • "Reduces bacteria, cysts, Giardia, Cryptosporidium, viruses" (examples of microbiological contaminants)

What does California Certification not cover?

CDPH certified water treatment devices are generally not intended for use where the raw water quality, such as ditch water, lake, pond or river water is unknown. CDPH certified water treatment devices are not intended to treat toxic wastes or waters with elevated levels of dangerous chemicals or in conditions where pH extremes might be encountered.

CDPH does not regulate shower filters, sports bottles or outdoor recreation water filters. CDPH does not regulate water softeners or water filters that make only aesthetic claims. Examples of aesthetic claims are claims to reduce taste and odor, including chlorine.

Independent and nationally recognized testing organizations National Sanitation Foundation (NSF), Water Quality Association (WQA) and Underwriter Laboratories (UL) evaluate and certify water treatment devices that meet minimum criteria for aesthetics claims under ANSI/NSF Standard 42. 

Do I need a water treatment device?

You should consider the following when deciding if you need or want a home water treatment device:

  • Does anyone in your household have a compromised immune system (chemotherapy, transplant patient, HIV) that would require drinking water of a higher quality than is required by the general public? For more information, call the EPA Hotline 1-800-426-4791.
  • Are you concerned with taste, odor, appearance, chlorine content, high mineral content (total dissolved solids, TDS), or hardness only? These devices are not regulated by CDPH. However, NSF International, Water Quality Association and Underwriter Laboratories (independent testing organizations) do certify the performance of water treatment devices for aesthetic claims. Look for the NSF, UL or WQA mark on packaging, advertising and the Performance Data Sheet.
  • Are you concerned about contaminants that might affect your health? You can obtain information about your water quality (see below).  If you believe that your water needs additional treatment, CDPH maintains a list of certified Water Treatment Devices in its directory.

How do I obtain information about my water quality? 

The easiest place to get this information is from the annual report (Consumer Confidence Report) published by your water utility (usually included with your water bill). State regulations require each community water system to provide specific information on water quality to their customers. 

If you are on a private well, ask your county environmental health department if it can provide any water quality information for your area. Your can also have your water tested by a private laboratory.


Do I need to test my water?  

Generally not, as testing can be expensive. However, having your water tested will tell you whether there are unacceptably high levels of any tested contaminant. Laboratories that test water samples are listed in the Yellow Pages under "Laboratories - Analytical". The lab you choose should be certified by CDPH's Environmental Laboratory Accreditation Program -- be sure to ask.

Sometimes household plumbing fixtures and materials can contribute contaminants such as lead or copper to the water. If you think that you may have a lead problem, have your water tested. If the test results show lead in your water, purchase a unit certified for lead reduction and remember to change the filter cartridges. Also, caution household members, especially children, to flush the tap before use.


How can I tell if a water treatment device is certified?

  • The device must have a label that includes the CDPH certification number.
  • A copy of the CDPH issued certificate must accompany the device. The certificate lists the contaminants that the filter has proven to effectively reduce. The certificate can be on the Product Data Sheet, separately inserted into the packaging, or a part of the owners manual.

Do I need to be concerned about non-certified devices?  

Yes, many fraudulent water treatment devices are being marketed. If a device is being sold on the basis of health claims and is not certified, there are two problems: (1) there is no reason to believe that it works as advertised and the product warranty and replacement parts will not solve the problem, and (2) the device is being sold illegally in California. Here are some questions to ask about any water treatment device that is being sold on the basis of health claims:

  • Is it certified by the State of California?
  • What specific contaminants does the device reduce? (Verify that they are listed on the certificate.)
  • What is the rated capacity of the device? (Also verify this on the certificate. Note: Some devices do not have a capacity.)
  • You can protect yourself by not buying an illegal and unproven device.

How do I report fraudulent devices?  

To report a suspected uncertified device, send the written material you received (containing health claims and the name of the device) along with the salesperson's business card to CDPH at the address below for follow-up investigation.


For More Information

For more information about certification of residential water treatment devices, contact us at: 

California Department of Public Health
DDWEM-Technical Operations Section,
Device Certification Unit
P.O. Box 997377, MS 7417
1616 Capitol Avenue
Sacramento, CA 95899-7377
(916) 449-5600 (phone) 
(916) 449-5656 (fax)

Last modified on: 6/2/2014 12:05 PM