Frequently Asked Questions
Do I really need a water filter?
Maybe. It depends on what’s in your water — which depends on where you live and where your water comes from. A simple water test tells you what you’re dealing with; then you match the filter to the problem. Guessing is how people waste money.
What’s actually in my tap water?
Usually chlorine or chloramines (added to kill germs), plus minerals like calcium and magnesium. Depending on your area, there can also be lead from old pipes, PFAS (“forever chemicals”), nitrates, or sediment. Your local water utility publishes a quality report every year — worth a look.
What’s the difference between a pitcher, an under-sink filter, and a whole-house system?
A pitcher is cheap and simple but slow, with limited filtration. An under-sink system filters the water at one tap — usually much more thorough. A whole-house system treats all the water coming into your home, including showers and laundry. Bigger coverage, bigger price.
How do I know which filter I need?
Test first, buy second. A basic water test kit (or your utility’s annual report) tells you what’s in your water. Then pick a filter certified to remove those specific contaminants. The most expensive filter isn’t the best one — the best one is the one that removes YOUR contaminants.
Do water filters remove fluoride?
Most standard carbon filters (like pitchers) don’t remove much fluoride. Reverse osmosis systems and distillation do. If fluoride is your concern, check the filter’s certifications before you buy.
How often do I need to change the filter?
Follow the manufacturer’s schedule — usually every 2–6 months for pitchers and faucet filters, 6–12 months for under-sink cartridges. An old filter is worse than no filter: it can dump everything it trapped back into your water.
Is bottled water better than filtered tap?
Usually not. Bottled water is often just filtered tap water in a plastic bottle, marked up thousands of times. A good home filter gives you the same quality for pennies per gallon — without the plastic waste.
What does “NSF certified” mean?
NSF International is an independent lab that tests whether a filter actually removes what it claims. Look for NSF/ANSI 42 (taste and odor), 53 (health contaminants like lead), or 58 (reverse osmosis). A filter without certification is running on promises.
Where can I find a local water treatment installer?
I don’t do installation — I do guidance. If you need a local pro, the Water Quality Association (the water treatment industry’s trade association) has a member directory: type in your ZIP code and it lists member dealers near you. It’s a solid starting point, not a blanket endorsement — check reviews and get multiple quotes, like you would with any contractor.
How do I find out what’s in MY tap water?
Two free tools, no filter company required. First, look up your water system’s annual Consumer Confidence Report — every city supplier has to publish one, listing exactly what was detected in your water last year.
Find your water system’s report
If the EPA’s tool gives you trouble on your phone, just google your water company’s name plus “water quality report” — most post it on their own site.
Second, punch your ZIP code into the EWG Tap Water Database to see detected contaminants in plain English.
On a private well? Those reports don’t cover you — start with a lab test instead.
See our Well Water Testing Guide
What does a filter’s micron rating mean — absolute vs. nominal?
A micron rating tells you what size of particle a filter catches. Two ratings tell you how certain that is:
• Absolute rating — the filter catches at least 99.9% of particles that size, every time. This is the stricter claim and the one that counts for health claims.
• Nominal rating — the filter catches most particles that size (usually 60–90%, depending on the maker). Useful, but not a guarantee.
For scale: a standard sediment prefilter runs 1–5 microns; carbon blocks that meet the NSF/ANSI 53 lead-reduction standard are typically built around a 0.5-micron pore size; ultrafiltration runs about 0.01–0.1 micron; nanofiltration about 0.001 micron; and reverse osmosis membranes run about 0.0001 micron — roughly ten thousand times finer than that 0.5-micron carbon block.