NSF 42 vs 53

This is a brief comparison between NSF 42 vs 53 standards for water treatment system.

Even NSF is not a legal requirement for water filters, it’s good to know about these certified in the case your a purchasing a water filter systems for your home.

NSF 42 vs 53 Comparison Table

 NSF-ANSI 42NSF-ANSI 53
ScopePoint-of-use and point-of-entry systemsPoint-of-use and point-of-entry systems
CoverAesthetic (taste and odor) claimsHealth-related claims
Reduction ClaimsChlorine, taste and odor, chloramine, particulate, iron, manganese, zinc and total dissolved
solids (TDS)
Over 50 contaminant reduction claims. Some of the most popular include: lead, Cryptosporidium, VOCs and chromium.
TestingMaterial safety, structural integrity and specific aesthetic-related contaminant reduction
claims (claims vary by product)
Material safety, structural integrity and specific health-related contaminant reduction claims
(claims vary by product)
POE Test period16 hours/day or the rated capacity of a filter is achieved16 hours/day or the rated capacity of a filter is achieved
POE Rest period8 hours/day8 hours/day
Gravity filter Test period2 - 6 gallons per day2 - 6 gallons per day
Plumbed-in filter systems Test period50% / 50% On/Off or a 10% / 90% On/Off cycle50% / 50% On/Off or a 10% / 90% On/Off cycle
Testing flow rateAt the manufacturer’s desired rate (Start at the 60 PSI flow rate)At 60 PSI flow rate
Testing conductedUntil it reaches 100% of the manufacturer’s anticipated reduction capacityMaximum:
- 120% of the manufacturer’s anticipated reduction capacity if testing with performance indication devices (PID).
- 200% of the manufacturer’s anticipated reduction capacity if testing without PID.
ExceptionIron and manganese are once conducted to 120% of the system’s reduction capacityNo exception