NSF/ANSI 40 - 2005


Due to co-operations between PIA and NSF, tests according to NSF / ANSI test standards 40 and 245 can also be performed in Europe at the test site of the PIA in Aachen.

The standard NSF/ANSI 40 specifies minimum requirements regarding material, design, construction and testing procedures, which a manufacturer of small/ residential wastewater treatment plants must meet, to obtain a license (Class 1 or Class 2) for the North American market.

The standard applies to systems that have a treatment capacity between 1514 l/d (400 gal/d) and 5678 l/d (1,500 gal/d).

Before the plant is tested, a visual material control and a 24-hour test of the plant’s infiltration and exfiltration resistance will be conducted by PIA..
After a start-up phase of 3 weeks, the actual examination begins and lasts for 26 consecutive weeks. During the examination samples are taken on 116 days. The examination includes the following loading scenarios:

16 weeks

design loading (5 samples/week)

7,5 weeks (52 days)

4 stress loading scenarios (separated by 7 days of design loading):

  • 3 wash days in a 5-day period
  • scenario working-parent stress, also 5 days
  • power failure for a period of 48 hours. (feed likewise 0% for 48 hours)
  • scenario vacation for a 10 days period including 8 consecutive days with 0% feed

2,5 weeks (18 days)

design loading (5 samples/week)


For questions concerning the NSF examinations, please contact: e.lance [at]