| Stage | Part number | What it does | Replace every |
|---|---|---|---|
| 1 | WD-10PP | PP sediment — blocks sand, rust, particulates | 6 months |
| 2 | WD-10GC | Granular carbon — chlorine, taste, odor | 8–12 months |
| 3 | WD-10CT | Carbon block + KDF — final polish, WQA certified | 12–18 months |
The correct annual buy: 2 × WD-10PP + 1 × WD-10GC + 1 × WD-10CT
Sold as the 1-Year Combo Pack — Home Depot model B-WD-2PPGCCT. Not the standard 3-filter set.
Before anything else: confirm you have a WD-TSA
Waterdrop sells several similar-looking under-sink systems and the filters are not interchangeable. Open the cabinet and read the part number printed on your installed cartridge. It should say WD-10PP, WD-10GC, or WD-10CT.
Two lookalikes to watch for: the WD-TSU and WD-TSC use WD-TSPP and WD-TSCT cartridges — one letter different, wrong fit. The WD-10UA and WD-10UB use a single WD-RF10 cartridge. If your cabinet has one filter body instead of three, you are in the wrong guide.
| System | Uses 10PP/10GC/10CT? |
|---|---|
| WD-TSA, WD-TSB | Yes — all three |
| WD-TSB-CM, WD-TSB-ALK, WD-TSA-UF, WD-TSB-UF | Partially — confirm each |
| WD-TSU, WD-TSC, WD-10UA, WD-10UB | No — different cartridges |
The three filters — what each one does
Water flows through them in order. Each stage protects the next — which is why the replacement schedule isn't arbitrary. A clogged stage 1 makes stages 2 and 3 work harder and shortens their life.
Stage 1 — WD-10PP
PP sediment filter
Advanced polypropylene membrane. Blocks sand, rust, particulates, and suspended solids. The shield that protects the carbon stages — if this clogs, flow drops and the GC and CT degrade faster.
Part: WD-10PP · Home Depot B-WD-10PP ($29.99) · Amazon ASIN B0CM8MHWNT
6 mo
Replace every
Stage 2 — WD-10GC
Granular activated carbon filter
Reduces chlorine, bad taste, and odor. Most of the perceived improvement in water quality happens here. If chlorine taste returns before your scheduled replacement, replace the GC early.
Part: WD-10GC · Amazon ASIN B0CM8KV1M9
8–12 mo
Replace every
Stage 3 — WD-10CT
Natural carbon block + KDF
Final polish — the last thing the water touches before your glass. The KDF component inhibits bacterial growth. This is the only certified element in the system: WQA-certified against NSF/ANSI 42 (model EWF-8016S) for 92.7% chlorine, taste, and odor reduction, and NSF/ANSI 372 for lead-free materials.
Part: WD-10CT · Home Depot B-WD-10CT · Amazon ASIN B0CM8SDWWD
12–18 mo
Replace every
What the WD-10CT certification actually covers
Retail listings describe reduction of PFAS, fluoride, and lead. The WQA certification Waterdrop publishes is NSF/ANSI 42 — which covers aesthetic effects (chlorine, taste, odor) — and NSF/ANSI 372 for lead content in the filter materials, not lead removal from water. Health-related contaminant reduction is covered by NSF 53, which is not claimed for this element. This doesn't mean the reduction claims are false; it means the certified performance and the marketed performance are different lists.
5-year replacement calendar
Based on Waterdrop's published lifespans using the longer end of each range — 12 months for GC, 18 months for CT. If your water is heavily chlorinated or usage is high, shift toward the shorter end.
| Month | WD-10PP | WD-10GC | WD-10CT |
|---|---|---|---|
| 0 — install | New | New | New |
| 6 | Replace PP | — | — |
| 12 | Replace PP | Replace GC | — |
| 18 | Replace PP | — | Replace CT |
| 24 | Replace PP | Replace GC | — |
| 30 | Replace PP | — | — |
| 36 | Replace PP | Replace GC | Replace CT |
| 42 | Replace PP | — | — |
| 48 | Replace PP | Replace GC | — |
| 54 | Replace PP | — | Replace CT |
| 60 | Replace PP | Replace GC | — |
What to buy — and the mistake to avoid
The most common mistake: buying the standard 3-filter set once a year
One of each filter leaves you one WD-10PP short every year. The sediment filter needs replacing every 6 months; the other two don't. You end up running an overdue sediment filter for six months, which degrades everything downstream.
| What to buy | Contents | Price (approx.) | Verdict |
|---|---|---|---|
| 1-Year Combo Pack | 2×PP + 1×GC + 1×CT | ~$107 | Correct. Matches the actual schedule. |
| Standard 3-filter set | 1×PP + 1×GC + 1×CT | $88.99 | Wrong for annual use — one PP short. |
| 3-Pack (2PP+GC) | 2×PP + 1×GC | Varies | Good for years when CT isn't due. |
| Singles as needed | Whichever filter is due | PP: $29.99 | Most precise — easiest to forget. |
| Autoship | 3-filter set on chosen interval | From $80.09 | Check interval — see warning below. |
Autoship warning: On a 6-month interval you receive a GC and CT every 6 months — far more carbon than you need. On 18-month, you receive one PP every 18 months — a third of what you need. Only the 12-month interval is close to right, and even then it's one PP short. If you subscribe, plan to buy PP filters separately.
How to replace the filters
The twist-lock design takes about 3 seconds per cartridge. The steps around it are what prevent a wet cabinet.
Shut off the cold-water supply valve
Then open your kitchen faucet on the cold side and let it run until flow stops — this relieves pressure in the system.
Lay a towel under the manifold
Position a shallow tray and have the new cartridge in hand before removing the old one.
Twist off the old cartridge
Support the filter body with one hand. Tip it upright as it comes free — it holds water and will run down your arm otherwise.
Wipe the seat, check the O-ring, insert new cartridge
Confirm the new cartridge's O-ring is seated evenly in its groove. Insert and twist to lock — it should seat positively without force.
Turn the water back on slowly
Quarter-turn, pause, half-turn, pause, then fully open. Watch the cap seams for the first 30 seconds as pressure builds.
Flush 5–10 minutes, then leak check overnight
New carbon sheds fine black dust — this is normal. Run until clear. Lay dry paper towels under every fitting and check in the morning.
Write the date on masking tape, stick it to the filter body
There is no electronic filter-life indicator on the WD-TSA. The tape label lives where the problem is and survives phone upgrades.
Troubleshooting
| Symptom | Likely cause | Fix |
|---|---|---|
| Black particles after new filter | Normal carbon fines | Flush 10–15 min. Should clear. |
| Particles persist past 15 min | Damaged cartridge or seal | Stop use, contact Waterdrop support. |
| Flow drops over months | Stage 1 sediment clogging | Replace WD-10PP; shorten interval. |
| Chlorine taste returns | GC filter exhausted | Replace WD-10GC early. |
| Drip from cap seam | O-ring pinched or misseated | Depressurize, inspect O-ring, wipe seat, reseat. |
| Cartridge won't twist off | System still pressurized | Shut supply, open faucet, let flow stop. Never use tools. |
| TDS meter shows no change | Expected — by design | The WD-TSA does not reduce TDS. Not a fault. |
| Musty taste | Filters overdue or system unused | Flush 5 min. If it persists, replace all three. |
Common questions
How often do I replace Waterdrop WD-TSA filters?
WD-10PP every 6 months, WD-10GC every 8–12 months, WD-10CT every 12–18 months. Simplified: PP twice a year, GC once a year, CT every 18 months.
What's the correct annual filter purchase?
2 × WD-10PP + 1 × WD-10GC + 1 × WD-10CT — sold as the 1-Year Combo Pack, Home Depot model B-WD-2PPGCCT. The standard 3-filter set (one of each) leaves you one sediment filter short every year.
Is the WD-TSA suitable for well water?
No. Waterdrop explicitly states the system is designed for municipal tap water on a cold supply only. It is also not suitable for hot water, and it does not reduce TDS. If you need dissolved solids removed, you need a reverse osmosis system.
What is the difference between WD-TSA and WD-TSB?
Same three filter cartridges and same replacement schedule. The WD-TSA connects to your existing kitchen faucet. The WD-TSB comes with its own dedicated lead-free brushed stainless faucet.
Why is there black in my water after replacing filters?
Normal carbon fines from new media. Run filtered cold water for 5 minutes, wait 5 minutes, run again for 5 minutes. Should clear within 10–15 minutes total. If particles persist beyond 15 minutes, contact Waterdrop support.