The right water filter depends on what is in your water and what you want changed. Here is how to work that out for a San Jose home before anyone sells you a system.
Water Softener San Jose is an independent referral service, not an installer or plumber. When you send the form, your details are passed to an independent local water treatment pro, who can contact you and prepare a quote. This page is a plain guide to the choices.
Start with what is in your water
Water filtration in San Jose begins with two documents you can get for free: your water bill, which names the company that supplies your home, and that company’s annual water quality report. If San Jose Water supplies you, its 2025 report covers its main system and the City of Cupertino system, lists its three sources (mountain surface water, groundwater and Valley Water treated surface water), and includes a map of which source feeds which area.
Consumer advice on home water treatment puts the next step as a question: what contaminant do you want to remove or reduce? Then select a unit certified by NSF, Underwriters Laboratories or the Water Quality Association to remove that contaminant, and make sure the certification covers it. Everything below follows from that.
- Read the report for what has been detected in your supply.
- Write down what you notice: a taste, a smell, staining, sediment, scale.
- If you want to know what reaches your own tap through your own pipes, have the water tested by a state-certified laboratory.
- Then choose equipment certified for that problem.
One tap or the whole house?
Filters come in two broad placements. Point-of-use filters treat water at one fixture: a filter on the faucet, under the sink, or a reverse osmosis system with its own drinking water tap. Point-of-entry filters sit on the main line and treat everything that comes into the house. The question is where the problem matters to you.
| Placement | What it treats | Fits when |
|---|---|---|
| Faucet or under-sink filter | One tap | You care about drinking and cooking water |
| Reverse osmosis at the sink | One tap, through a membrane | You want a membrane system for drinking water |
| Whole-house filter | Every tap, shower and appliance | Taste, odor or sediment through the house |
| Water softener | Every tap (hardness only) | Scale, spots and soap that will not lather |
The two pages that go deeper are reverse osmosis in San Jose for the under-sink membrane system and the whole house water filter in San Jose for treatment on the main line.
The standards that tell you what a filter does
Water filtration products carry all kinds of claims. The NSF/ANSI standards are how you check them. Each covers a kind of equipment or a kind of effect, and a product’s certification listing names exactly what it was tested to reduce.
| Standard | What it covers |
|---|---|
| NSF/ANSI 42 | Aesthetic effects, such as chlorine, taste and odor |
| NSF/ANSI 53 | Health effects, such as lead |
| NSF/ANSI 55 | Ultraviolet (UV) systems, Class A and Class B |
| NSF/ANSI 58 | Reverse osmosis drinking water systems |
| NSF/ANSI 401 | Certain incidental contaminants |
| NSF/ANSI 44 | Residential water softeners (hardness) |
Two words to be careful with: certified and purified. Ask what a unit is certified to reduce, by name, under which standard. And treat any claim that a filter makes water pure or safe with caution: a certification lists specific contaminants and test results, not a general promise.
Not sure which filter fits? Send the form and an independent local pro can contact you about your water.
Taste, staining and what EPA’s guidelines say
EPA sets secondary standards for 15 contaminants: non-mandatory guidelines for aesthetic considerations such as taste, color and odor, which EPA does not enforce. They help you read a report or a lab result.
- Iron above 0.3 mg/L can mean rusty color, sediment, a metallic taste and reddish or orange staining.
- Manganese above 0.05 mg/L can mean black to brown color, black staining and a bitter metallic taste.
- Chloride above 250 mg/L can taste salty.
- Total dissolved solids above 500 mg/L can mean hardness, deposits, colored water, staining and a salty taste.
- The guideline range for pH is 6.5 to 8.5.
Hardness is not on EPA’s table and has no health-based standard. San Jose Water says hard water does not pose a health risk. If the trouble is scale and spots, the equipment you want is a softener: see water softener installation in San Jose.
PFAS and filtration
PFAS is another reason people ask about filters. San Jose Water’s 2025 report says it monitors 88 groundwater wells and 9 surface sources for PFAS. EPA’s final rule set enforceable limits of 4.0 parts per trillion for PFOA and for PFOS; on May 18, 2026 EPA proposed keeping those limits with up to two more years, to 2031, for water systems to comply, and proposed rescinding the limits for four other PFAS. When this page was written those changes were proposals, not final rules; EPA’s PFAS page has the current status.
For treatment at home, EPA’s WaterSense program lists PFAS among the contaminants reverse osmosis systems can potentially remove. For any filter, check the certification listing for the specific PFAS you are concerned about.
Where ultraviolet systems fit
Ultraviolet (UV) systems are a different kind of treatment from filters: they expose water to UV light rather than passing it through a medium. NSF/ANSI 55 is the standard for them, with two classes, Class A and Class B. If a UV system is suggested for your home, ask which class it is certified to, what it is meant to treat in your water, and what the maker says about lamps and upkeep.
For a home on city water, ask why UV is needed for your supply, and look at the report before you decide. Our page on water treatment in San Jose sets UV beside the other options.
What affects the cost of water filtration
This site gives no prices: no installer is named and every home differs. These are the things that change the job, so you can read a quote with them in mind.
- One tap or the whole house.
- The type of system, and what it is certified to reduce.
- Whether a softener goes in on the same visit.
- Where the main line or the sink plumbing is, and how easy it is to reach.
- Whether a drain connection or a new faucet is needed.
- Replacement cartridges, media or membranes over time, on the maker’s schedule.
Choosing a system without star ratings
Search for the highest rated water filtration system and you will find lists, rankings and reviews. A more useful test is the certification: does the unit’s listing name the contaminant you care about, under the right NSF/ANSI standard? A filter certified for chlorine taste and odor under NSF/ANSI 42 is not the one to buy if your concern is lead, which NSF/ANSI 53 covers.
Questions to ask before you buy a water filter
- What problem is this system meant to solve in my water?
- Which contaminants is it certified to reduce, under which NSF/ANSI standard?
- One tap or the whole house, and why?
- Do I also need a softener for the hardness of my water?
- What does the maker say about replacing cartridges, media or membranes?
- Does the install need a plumbing permit? (For San Jose, check with the City of San Jose permit center.)
- Is everything in the price written down so I can compare it with another quote?
For a side-by-side look at softeners, filters, reverse osmosis and UV, see water treatment in San Jose. When you are ready, send the form with your ZIP code. Asking is free and you never have to buy.
Questions people ask
How do I choose a water filter in San Jose?
Start with your water provider’s annual report and what you notice at the tap, decide what you want to reduce, then pick a unit certified to reduce it under the right NSF/ANSI standard.
How much does it cost to put in a water filtration system?
This site gives no prices. The cost depends on one tap or the whole house, the type of system, access to the plumbing, and replacement parts over time. Ask for a written quote.
Is a water filter the same as a water softener?
No. A softener works on the calcium and magnesium that cause hard water. A filter is chosen for taste, odor, sediment or a specific contaminant.
What does NSF/ANSI 53 mean on a filter?
It is the filter standard for health effects, such as lead. Check the listing for the specific contaminants a unit is certified to reduce.
Is San Jose tap water safe to drink?
Read your water provider’s annual water quality report for the test results in your supply. This site makes no health claims about tap water or about filtered water.