Water Filters for Los Gatos Homes: What’s in Your Tap Water and Which Filter Does What

With PFAS and microplastics in the news, a lot of people are wondering whether they should be filtering their tap water. It’s a fair question, and the honest answer starts with some good news. San Jose Water’s 2025 water quality report shows that the water it delivered met every state and federal drinking water standard.

So for most families, filtering isn’t about making unsafe water safe. It comes down to three things: better taste, less scale on your fixtures and appliances, and peace of mind. Here is what’s actually in our local water, in plain terms, and which kind of filter handles what.

Where Your Water Comes From

San Jose Water serves most homes in Los Gatos, Saratoga, Monte Sereno and Campbell, and it draws on three sources:

• Mountain surface water from the Los Gatos Creek and Saratoga Creek watersheds in the Santa Cruz Mountains, where San Jose Water manages about 6,000 acres of protected land.
• Groundwater from local wells.
• Treated surface water from Valley Water.

Which one reaches your faucet depends on where you live, and many homes get a blend. The map in San Jose Water’s 2025 water quality report shows the main source for your neighborhood.

What’s in It Worth Knowing

Hardness. All three sources are hard water. In the 2025 report, mountain water averaged about 151 parts per million (9 grains per gallon), groundwater averaged 288 ppm (about 17 grains) and Valley Water about 99 ppm. The calcium and magnesium are harmless to drink, but they are what leave white spots on glasses and scale inside water heaters. We covered that in our post on hard water in Saratoga.

Chlorine and chloramine. San Jose Water uses these to keep the water free of germs on its way to you. They are safe at these levels, but they are the slight pool taste or smell some people notice.

PFAS. These are the “forever chemicals” you may have read about. San Jose Water has tested for them since 2019, with more than 16,000 samples. Its mountain surface water came back essentially PFAS free. In groundwater, PFOS was above California’s notification level at 2 of 76 active wells, both at one station where a treatment facility has been designed and construction is expected to begin in 2026 or 2027. A related compound, PFHxS, showed up above the notification level at several wells, still well below the level where action is required. San Jose Water also voluntarily took 10 wells out of service between 2019 and 2024. If PFAS is on your mind, a certified filter at your kitchen tap adds an extra layer.

Which Filter Does What

Not every filter does the same job, and the box doesn’t always make that clear. Look for the NSF/ANSI certification on the label, which tells you what the filter has actually been tested to reduce.

• Pitcher and refrigerator filters. Good for taste and chlorine. Many are certified only to NSF/ANSI 42, the taste and odor standard. Some are certified for more, so check the label.
• Under-sink filters. A dedicated filter that feeds your kitchen faucet or a small separate faucet. Models certified to NSF/ANSI 53 are tested for health-related contaminants such as lead, and many are also certified for PFOA and PFOS.
• Reverse osmosis. Water is pushed through a very fine membrane, usually in a compact system under the kitchen sink with its own small faucet. It reduces the widest range of things, including PFAS and most dissolved minerals (NSF/ANSI 58). It sends some water down the drain as it works, and the filters and membrane need changing on schedule.
• Whole-house systems. These treat all the water coming into the house, so showers and laundry get it too. They are a good fit for chlorine or chloramine taste and smell. Chloramine needs a filter rated for it.
• Water softeners. A softener isn’t really a filter. It swaps out the hardness minerals to protect your water heater, fixtures and appliances. Some whole-house systems combine a softener and a filter in one, and many homes pair one with an under-sink filter or reverse osmosis for drinking water.

A Filter Only Works if You Keep Up With It

Cartridges and membranes wear out. Once a filter is past its life it stops doing its job, and an aging filter housing is one of the slow leaks we find under kitchen sinks. When a new filter goes in, put the next change date on your calendar.

How We Can Help

Every home’s water is a little different. Whether it’s the taste, scale on your fixtures, a softener that has stopped keeping up, or you just want a better tap for drinking water, we will tell you plainly what would actually help. That might be an under-sink filter, reverse osmosis, a whole-house system or a softener. Our family has been taking care of Los Gatos homes since 1988. Call us at (408) 358-6446 or learn more about our water treatment services.