What is the NSF 350 Greywater Certification?

Greywater Certification

What is the NSF 350 Greywater Certification?

Greywater certification through NSF 350 is a rigorous process manufacturers pursue to display the NSF mark on their products. This process includes 26-weeks of continuous third-party testing during which system maintenance or process adjustments are not allowed, a review of design specification compliance, and a satisfactory 7-year audit history.

If a manufacturer has successfully completed the NSF 350 certification review, their product will have demonstrated satisfactory treatment for biochemical oxygen demand (BOD5), total suspended solids (TSS), turbidity (NTU), and bacteria (e-coli), among other test parameters.

Being tested and certified by NSF to meet their 350 standard is a great way for a product to show that it consistently meets high water quality requirements with minimal maintenance or operator intervention.

There are 2 categories of NSF 350 certification, residential (R) – Single Family Residential Dwellings and commercial (C) – Multifamily Residential Dwellings and Commercial Facilities.  The (C) certification tests are more stringent than the (R) testing with for example a lower level of e.coli allowed.  Both categories have ratings for the amount of water that can be processed on average each day.   (C) rated systems can be scaled to large capacities by using multiple certified units. 

Currently, only Aqualoop is NSF 350 certified and tested by NSF for greywater recycling for Class C applications. Aqualoop uses moving bed-membrane bioreactor (MB-MBR) technology and equipment to process water on-site for use in non-potable fixtures. More information about Aqualoop and other INTEWA products can be found at https://www.ecoviewater.com/.

Within each of these categories are 4 types of influent source water with which products can be certified.  Each has different water quality levels for the parameters listed above.  Here are the four types, listed in order of lowest water quality (dirtiest) and highest (cleanest):

  • Waste Water – Also, referred to as Blackwater.
  • Greywater (Laundry)
  • Greywater (Bath+ Laundry)
  • Greywater (Bath Only)

The NSF 350 listing is required in many states and municipalities for greywater treatment products. Without it, designer engineers and developers may need to prove their treatment system through independent review and additional testing during permitting, if the product is even considered. Using a pre-certified product can save the valuable permitting time.

Building owners benefit from NSF 350 certified products with the knowledge that the certified product has proven excellent water quality and low maintenance requirements.

Examples of NSF 350 Certified Products:

NSF 350 certification is time-intensive and difficult to obtain for manufacturers.  Many manufacturers make claims of NSF 350 compliance without being actually 3rd party tested and certified.  Some even make fraudulent claims of actually being tested and certified by NSF to meet the 350 standard.  Others are 3rd party certified by other organizations (not NSF).   Here is what to look for to make sure a greywater treatment system has been tested by NSF to meet 350 (C) certification:

  1. Is the product found on the NSF website link for the 350 standard? To check if a manufacturer’s product is certified through NSF, the product can be searched by either industry type or company name at CLICK HERE to see the current listings. If a product is not shown on this link, it has not been tested and certified by NSF to meet the 350 standard. 


  1. Can the manufacturer produce the certification document from NSF showing the 350 test results? Here is the document for Aqualoop.  If the manufacturer cannot provide this documentation, then the product may not be certified by NSF.
  2. Does the manufacturer display the NSF logo indicating the product is NSF 350 certified? Only systems certified by NSF can use the NSF logo.NSF350 Certification
  3. Is the greywater product certified for the type of greywater that is planned to be recycled for the building; namely, bath only, bath+laundry, or laundry only? They’re actually fairly large differences between the different types of greywater sources.  Greywater from bath only is easier to process than bath + laundry which is, in turn, easier to process than laundry only.
  4. Has the greywater product been installed and operated in other similar applications? That is, does the product have a proven track record of success? 

Why is Greywater Recycling Important?

The United States southwest and west are examples of where implementing greywater recycling for new construction and redevelopment construction has a significant impact. As drought conditions continue to worsen, stored water in snowpack and reservoirs are becoming depleted and less dependable. Add the additional factor of a growing population and water scarcity becomes a more relevant concern. While many communities can take advantage of rainwater collection that requires minimal treatment, many geographies west of the Mississippi do not have this opportunity.

This is where greywater recycling becomes a very viable alternative. Consider that over half of a single-family home’s water discharge is considered greywater. This means it did not come from the toilet or kitchen sink. An average family of 5 would consume 250 gallons of water per day. By using an NSF 350 certified greywater treatment system, that household can supply up to 150 gallons of water per day rather than sending it to the municipal treatment plant or backyard septic system. Scale that system to a commercial multifamily complex or a new office high rise, and the total amount of water conservation increases dramatically. For this reason, products that are NSF 350 tested and certified become more and more valuable.

Greywater recycling solutions that are implemented building-by-building and site-by-site help to reduce wastewater system peak flows, reduce overall water system demand, conserve water, and ultimately increase a community’s water resiliency.