What water treatment systems suit Valley homes?

Not much for safety. Tempe's water utility says its water meets federal, state and local standards, so secondary treatment devices are not needed. It adds that some people install treatment for aesthetic reasons such as hardness deposits or chlorine taste. Those are secondary standards, not health limits. Phoenix takes the same position in its report, describing taste, odor and hardness as harmless aesthetic aspects.

So the honest starting question is what bothers you, not what to buy. The CDC's own advice is to test your water and choose a system that removes the harmful chemicals or germs you are concerned about, and it says that if your tap water does not contain harmful germs or chemicals, you may not need a system at all.

Three problems come up over and over in Valley homes.

1. 1Hardness. Phoenix reports 172 to 302 milligrams per liter, or 10 to 17.6 grains per gallon. Mesa reports about 12 in its City Zone and about 16 in its Eastern and Southern zones. Our page on hardness by Valley city has the details.
2. 2Taste and smell. Chlorine, and in late summer an earthy or musty note. Phoenix says algae in the canals are a major source of the musty odor.
3. 3Specific contaminants you want lower, such as arsenic, lead from old plumbing, or nitrate. Our page on what contaminants are in Arizona tap water lists what the city reports show.

A water softener is the fit for hard water. NSF/ANSI 44 covers softeners, which use a cation exchange resin, regenerated with sodium or potassium chloride, to reduce hardness by swapping calcium and magnesium ions for sodium or potassium ions. The CDC says softeners remove minerals, primarily calcium and magnesium, and that hard water leaves scaly buildup and can stop soap from lathering. The CDC adds that some softeners may also remove other substances, and to check the product's label for the specific chemicals it removes.

Phoenix's report says hard water can cause scaling in pipes and water heaters and on faucets and showerheads. That is the case for treating hardness at the whole house, where the water heater and the pipes benefit, not just the kitchen tap. Our page on how hard water damages plumbing explains the damage.

A few practical points for a Valley install.

• Set it to your real number. Mesa recommends setting a softener at 16 grains per gallon and adjusting to your needs. In other cities, use your city's figure or a test at your tap.
• Know what a softener is not. It is not a drinking-water purifier. It does not remove germs, per the CDC.
• Know the alternatives. Salt-free systems are sold as scale reducers, and our page on whether salt-free softeners work covers what they do. For the difference between a softener and a conditioner, see water softener vs conditioner.

You have two main choices at the kitchen tap.

A certified carbon filter. NSF/ANSI 42 covers filters certified for aesthetic impurities such as chlorine, taste and odor, and NSF/ANSI 53 covers filters certified for contaminants with a health effect. The CDC says filters like these improve taste and smell, and the certified ones can also reduce specific chemicals such as lead. Check the label for the claim.

Reverse osmosis. The CDC says RO removes parasites, bacteria and viruses, removes some chemicals including lead, copper, chromium and sodium, and may reduce arsenic, fluoride, nitrate and others. NSF/ANSI 58 covers these systems. It is a bigger install than a filter, and the EPA notes it needs filter cartridges and the RO membrane replaced and sends untreated water down the drain. Our page on whether reverse osmosis is worth it covers the trade-offs, and reverse osmosis versus a softener explains why they do different jobs.

Here is how to choose between them.

• Taste and chlorine only: a certified carbon filter is enough.
• A specific chemical from your test or report: RO, or a carbon filter certified for that chemical.
• Both hard water and drinking water concerns: a softener for the house, plus one of the above at the kitchen tap. The CDC says you can use multiple types of systems to remove germs or chemicals more effectively.

City water is disinfected before it reaches you. Phoenix says its entire supply is disinfected with chlorine before delivery. Private wells are different. The CDC recommends testing a private well at least once a year for germs and chemicals. If a test shows germs, UV is one answer. NSF/ANSI 55 covers UV systems that inactivate bacteria, viruses and cysts, and the CDC says UV with pre-filtration removes parasites, bacteria and viruses but no chemicals. Our page on how UV, carbon and RO differ compares the three.

Well water also often needs a sediment stage and sometimes a softener or metal treatment, depending on the test. Let the lab result choose.

Treatment adds upkeep, and skipping upkeep can make things worse, not better. Tempe warns that secondary treatment devices may cause more water quality problems if not properly maintained. Phoenix's report warns that not following the manufacturer's instructions for operation and maintenance can result in potentially unsafe water.

Keep these five rules in mind.

1. 1Test first. Read your city's annual report, and test your own tap if your plumbing is old or you are on a well. Our page on how to read a tap water quality report shows you how.
2. 2Match the system to the problem. A softener does not purify, a carbon filter does not disinfect, and UV does not remove chemicals.
3. 3Look for NSF certification that names your specific concern. NSF says certification does not mean a product reduces every contaminant.
4. 4Plan for maintenance. Salt refills, cartridge changes and membrane swaps all come with ownership. Our page on how often to change a whole-house water filter explains cycles.
5. 5Be careful with whole-home chlorine removal. The CDC warns that a whole-home filter that removes chlorine or other disinfectants may let more germs grow in your plumbing.

If you would like a second set of eyes, we can look at your plumbing and your water report, recommend only what the problem calls for, and give you an upfront price before any work starts. The estimate is free.

### Quick answers

Here are the short versions.

Do I need a whole-house system? For hard water, a softener at the main line is the usual answer. For drinking water, a tap-level system is usually enough.

Is treatment needed for safety on city water? Tempe says its water meets standards and secondary devices are not needed. Many people choose treatment for scale and taste.

Can I combine systems? Yes. The CDC says multiple types can be used together.