Waterdrop TSA 8 Layer Under Sink Water Filter System, Under Sink Water Filtration System, Reduces PFAS, PFOA/PFOS, Fluoride, Chlorine, Bad Taste & Odor, NSF/ANSI 42 Certified Element, USA Tech

What it is and where it fits

The Waterdrop TSA is an under-sink, inline filtration system that replaces nothing on your counter and filters everything on your cold-water line. It’s aimed squarely at households on municipal water who want better taste and odor, less chlorine, and some targeted contaminant reduction (PFAS/PFOA/PFOS, fluoride, and certain heavy metals) without the complexity or waste of reverse osmosis. It does not reduce TDS and it keeps beneficial minerals in the water, which is either exactly what you want—or a deal-breaker—depending on your goals.

I installed the TSA on my kitchen’s cold feed so the main faucet dispenses filtered water. If you’d rather preserve full-flow for rinsing and only filter for drinking, it’s also easy to plumb to a separate drinking faucet; just plan your adapters ahead.

Installation and design

Installation is refreshingly straightforward. The manifold is compact and mounts flat against the cabinet wall, leaving plenty of room for cleaners and a trash bin. Waterdrop includes push-to-connect fittings and adapters for common 3/8-inch or 1/2-inch connections. My installation took about 20 minutes: shut off the cold supply, disconnect the line to the faucet, mount the bracket, cut and seat the tubing, then leak-check. The push-to-connects are forgiving as long as you squarely seat the tubing; a light tug confirms it’s locked.

After install, I flushed the system for several minutes (I ran a few pitchers through) to clear air and carbon fines. Expect a short period of slightly cloudy water with microbubbles—that’s normal in the first 5–10 minutes. Once the air purged, flow stabilized and the water ran clear.

Build quality is better than most plastic under-sink filters I’ve used. The manifold feels rigid, and the cartridges twist-lock with a positive, quarter-turn motion. Waterdrop touts high-pressure testing (burst and cycle) and I didn’t see any weeping at fittings or the housing. The system survived a few quick on/off cycles and full faucet blasts without a hiccup.

Filtration architecture and claims

This is an 8-stage setup delivered through three cartridges:
- A sediment stage that catches rust, sand, and silt.
- A KDF/resin stage targeting heavy metals and fluoride.
- A carbon block (coconut shell) stage that reduces chlorine, taste, and odor.

The carbon block is certified to NSF/ANSI 42 (via IAPMO) for chlorine taste and odor reduction. That’s the certification that matters most for taste. Waterdrop also markets PFAS/PFOA/PFOS and fluoride reduction. I don’t have a home lab to verify PFAS reduction, and the system isn’t positioned as a full NSF 53/401 contaminant-reduction platform. If PFAS is your primary driver, I’d ask Waterdrop for third-party test data for your flows and change intervals—or consider a certified alternative. For fluoride, the resin-based approach can be effective, but again, certification and source-water chemistry matter.

In day-to-day use, the difference in taste is the headline: the sharp chlorine edge disappeared, and both coffee and tea improved. Using simple test strips, my free chlorine dropped from approximately 1.5 ppm at the tap to undetectable at the faucet after filtration. That aligns with the spec and the immediate sensory improvement.

Note on materials: the carbon block uses coconut shell. Most people won’t have any issue, but if you have a severe coconut allergy, consult your physician before using coconut-shell carbon.

Flow, pressure, and day-to-day use

Inline systems rise and fall on flow. Measured with a one-gallon pitcher, I averaged about 63 seconds to fill, which works out to roughly 0.95–1.0 GPM on my line pressure. That’s more than enough for drinking, cooking, and rinsing produce. I do notice the flow limit when filling large stockpots from the cold side. If you regularly need high-flow cold water, route the TSA to a dedicated drinking faucet to avoid “throttling” your main faucet.

Noise is a non-issue; no buzzing or hammering in my setup. The cartridges stayed quiet and solid during on/off cycles.

Maintenance and filter life

There are three cartridges with staggered lifespans: roughly 6 months for the sediment stage, 8–12 months for the KDF/resin stage, and 12–18 months for the carbon block, depending on your water quality and usage. I appreciate not having to change all three at once—swapping the sediment filter at six months kept flow snappy and protects the downstream stages. The twist-and-lock cartridges make changes a 30-second task, and the manifold’s vertical orientation avoids drips all over the cabinet floor.

Practical tips:
- Keep a spare sediment cartridge on hand; it’s the one most likely to slow your flow if your city does line work or you get a seasonal turbidity spike.
- If you’re away for a few weeks, cap or bag the cartridges to avoid drying; Waterdrop suggests refrigerating them for trips up to 30 days (never the freezer).
- Mark change dates where you can see them. Staggered intervals are great in theory, but they’re easy to forget in practice.

In terms of cost of ownership, it’s solid for an inline system. Without quoting specific prices (they fluctuate), you’re generally looking at a low annual cost compared to reverse osmosis, especially if you buy multi-packs of replacements. There’s no waste water, no storage tank, and no re-mineralization to fuss with.

What it doesn’t do

• It does not reduce TDS. If you test with a TDS meter, expect little to no change. That’s by design; the TSA retains dissolved minerals like calcium and magnesium.
• It’s not a scale/softening solution. If your goal is fewer spots on glassware or less kettle scale, this won’t address hardness.
• It’s for cold, municipal water only. If you’re on a private well, you’ll want pre-filtration sized to your water’s sediment and iron profile—or a different system entirely. Don’t plumb it to hot water.
• It’s not a certified heavy-metals or PFAS “catch-all.” While the KDF/resin stage targets these, check for contaminant-specific certifications or lab data if you need guaranteed reduction to a particular threshold.

Reliability and cabinet fit

The form factor is cabinet-friendly. I mounted it toward the back wall and still had clearance for a pull-out bin. The integrated manifold simplifies the layout—no spaghetti of housings and hoses to contend with. Over several months, I saw no leaks or cartridge wobble, and the fittings remained dry. If you live in a very cold climate with unconditioned cabinetry, the thicker housing materials inspire confidence, but you should still protect the area from freezing.

Who it’s for

• Apartment and homeowners on municipal water who primarily want better taste and odor and a cleaner baseline for cooking and drinking.
• Households wary of PFAS who prefer a non-RO approach and are comfortable reviewing manufacturer test data for peace of mind.
• Anyone who dislikes the clutter of countertop filters and wants a quick, leak-resistant install with minimal maintenance.

Who should look elsewhere:
- Those needing certified reduction for a long list of contaminants (lead, cysts to NSF 53, pharmaceuticals to NSF 401, etc.)—consider a certified RO or a more robust carbon block system.
- Users on well water without proper pre-filtration.
- People expecting “bottled water” TDS numbers or soft water.

The bottom line

The Waterdrop TSA nails the fundamentals of an under-sink inline filter: easy installation, cabinet-friendly size, clean taste, and predictable maintenance with staggered cartridge life. The NSF/ANSI 42 certification for chlorine taste and odor is the meaningful, verifiable piece, and it shows in the glass. Flow is strong for an inline design, and the build feels sturdier than many budget three-stage systems.

I recommend the TSA for municipal-water households who want a low-hassle upgrade in taste and odor, prefer to keep minerals, and appreciate a compact, leak-resistant package. If you need guaranteed reduction for specific contaminants like PFAS to certified thresholds, ask Waterdrop for independent lab data—or step up to a system certified for those claims. For most city-water kitchens, though, this strikes an excellent balance of performance, simplicity, and cost of ownership.