ZeroWater makes a specific promise: bring total dissolved solids in your water to near zero. It keeps that promise. The included TDS meter reads your tap water, you filter, and the number drops to 0 or 1.

That’s worth something. But the cost to maintain it depends entirely on where you live, and in many US cities, the math doesn’t favor ZeroWater.

How It Works (and Why TDS Matters Here)

Most pitcher filters use activated carbon to reduce contaminants through adsorption. ZeroWater uses a 5-stage system that adds ion exchange resin, which actually strips dissolved minerals from the water. That’s what brings TDS to near zero.

Ion exchange works by trading sodium ions for dissolved minerals and contaminants. It’s effective, but the resin has a finite capacity. Once the resin is saturated, it stops exchanging. How quickly it saturates depends on how much dissolved material is in your source water, measured as TDS.

High TDS water (lots of dissolved minerals) exhausts the filter fast. Low TDS water extends the filter life considerably.

The NSF Certifications

ZeroWater holds NSF/ANSI 42 and NSF/ANSI 53 certifications. That covers:

• Chlorine taste and odor (NSF 42)
• Lead reduction (NSF 53)
• Mercury (NSF 53)
• Chromium (NSF 53)
• Benzene (NSF 53)

These are real certifications, verifiable in the NSF database. ZeroWater removes lead and mercury through ion exchange, and the NSF 53 standard confirms this.

What ZeroWater does not remove: PFAS. The manufacturer has confirmed ZeroWater filters are not certified or tested for PFAS removal. No NSF P473 certification exists for ZeroWater. If PFAS is a concern, you need Clearly Filtered or a reverse osmosis system.

ZeroWater also doesn’t meaningfully reduce fluoride, nitrates, or arsenic at NSF-certified levels.

The Filter Life Problem

This is the part that matters most before you buy.

ZeroWater’s filter replacement frequency is directly tied to your source water’s TDS. Here’s what that looks like in practice:

• Low-TDS cities (Seattle, Boston, Portland, San Francisco, typically 20-60 mg/L TDS): filter lasts about 35-45 gallons
• Medium-TDS cities (Chicago, Atlanta, Denver, typically 80-150 mg/L TDS): filter lasts about 20-30 gallons
• High-TDS cities (Las Vegas, Phoenix, Dallas, parts of Southern California, 200-400+ mg/L TDS): filter lasts about 10-20 gallons

Replacement filters cost about $12-15 each. At 15 gallons per filter in a high-TDS city, you’re paying about $0.80-$1.00 per gallon of filtered water.

For reference, Clearly Filtered runs about $0.10-0.14 per gallon on subscription. A Brita Longlast+ runs about $0.15-0.18 per gallon. The cost difference in a high-TDS city is enormous.

Check current pricing (affiliate link, see disclosure above)

How to Check Your TDS Before Buying

ZeroWater includes a TDS meter with every pitcher. You can also get one for about $15 on Amazon and test your tap before committing to ZeroWater as your regular filter.

Alternatively, most municipal water utilities publish an annual Consumer Confidence Report (CCR) that includes TDS or conductivity. Your city’s water report is usually findable with a search for “[city name] water quality report.” ZeroWater’s website also has a filter life estimator tool where you enter your TDS reading and household usage.

If your TDS is above 150 mg/L, do that math before buying.

The Fishy Smell: What It Means

Many ZeroWater users report a fishy odor from their water before they realize the filter needs replacing. This happens when the ion exchange resin exhausts and begins releasing trimethylamine, a compound with a distinct fishy smell.

It’s reliable: the smell means the filter is done. Replace it immediately when you notice it. Continuing to use an exhausted filter means you’re getting unfiltered water plus a bad taste, with no removal benefit.

Setting a filter replacement reminder based on your calculated gallons (from TDS testing) is more reliable than waiting for the smell.

Pitcher Sizes and Options

ZeroWater makes pitchers from 5-cup up to 22-cup. The 10-cup and 12-cup sizes are most common. All pitchers use the same filter cartridge. The 22-cup ready-pour version includes a spigot for dispensing without lifting. That’s useful if you fill large bottles frequently.

All pitchers include the TDS meter.

Who ZeroWater Is Right For

Low-TDS cities where filter life is reasonable (35-45 gallons per filter). Households that specifically want near-zero dissolved solids, for making coffee, feeding fish tanks, or mixing formula where mineral content matters. People targeting lead and mercury removal at a lower upfront cost than Clearly Filtered.

In Seattle, Boston, or Portland, ZeroWater makes practical sense. The filter life is workable, and the TDS reduction is real.

Who Should Look Elsewhere

Households in Phoenix, Las Vegas, Denver, Dallas, or any city with TDS above 150 mg/L should calculate their expected monthly filter cost before buying. At 15 gallons per filter, a family of 4 goes through two filters per month. That’s $25-30/month just in filters, for a product that doesn’t remove PFAS.

Anyone concerned about PFAS should use Clearly Filtered. Full stop. ZeroWater isn’t in the conversation for PFAS.

Anyone on a budget who wants reliable lead and taste improvement: Brita Longlast+ at 120 gallons per filter is more cost-effective at most TDS levels.

Concrete Recommendation

Before you buy ZeroWater, check your source water TDS. Either use the included meter (if you already own the pitcher) or look up your city’s water report. If TDS is above 150 mg/L, calculate your monthly filter cost. For many US households, Clearly Filtered or Brita Longlast+ will be cheaper per gallon while offering better or comparable contaminant coverage.

If TDS is below 100 mg/L, ZeroWater is a reasonable choice with real NSF 53 certifications and a unique ability to strip dissolved solids completely. Just replace the filter before the fishy smell starts.

For a full side-by-side of ZeroWater, Brita, and Clearly Filtered, see the best pitcher water filters guide.

Test your water before choosing treatment. Source water TDS varies dramatically by region. Filter life estimates depend on actual source water composition.