iSpring WGB21B-PB vs Pentair Pentek FloPlus Protect 20BB

Last updated: November 2, 2026

The iSpring WGB21B-PB is the better whole-house water filter overall, rated 2.6 to 2.0. The iSpring WGB21B-PB leads on flow. The iSpring WGB21B-PB costs $27.01 less ($230.99 vs $258).

iSpring WGB21B-PB vs Pentair Pentek FloPlus Protect 20BB

Prices were last checked November 2, 2026 and are subject to change; the price and availability shown by the retailer at the time of purchase apply.

Which should you buy?

Scores side by side

Each factor is scored 0-100 against the same fixed reference points for every cartridge whole-house water filter; a clear win is highlighted. How we rank explains each one.

Factor weightiSpring WGB21B-PBPentair Pentek FloPlus Protect 20BB
Overall rating2.6/52.0/5
Running cost 25%8 $2.44 per 1,000 gallons ($121.99 every 50,000 gallons)0 $4.69 per 1,000 gallons ($187.46 every 40,000 gallons)
Certification 25%0 no certification in a public listing, no tested to claim0 no certification in a public listing, no tested to claim
Flow 15%100 15 gpm service flow0 5 gpm service flow
Price 20%74 $230.9968 $258
Warranty 15%0 1-year warranty0 warranty not published, scored as none

Specifications

iSpring WGB21B-PBPentair Pentek FloPlus Protect 20BB
Filtration
Capacity50,000 gallons40,000 gallons
Replacement filters or media$121.99$187.46
Running cost$2.44 per 1,000 gal$4.69 per 1,000 gal
Stages21
ChloramineYesNo
PFASNoYes
Build
Flow15 gpm5 gpm
Ports1 in1 in
UV stageNoNo
Warranty1 year-

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