Yes, these 17 Series Check Valve are suitable for potable water systems! 
Both the 17YBCV (NL Yellow Brass) series and the 17CV (NL Bronze) series have third party NSF/ANSI-61 certification. And are suitable for projects NSF/ANSI-61 certification is mandated.
The 17CVSS (304SS) series does not currently have official third party NSF/ANSI-61 certification.
Stainless steel valves have been widely used in plumbing / water well systems for many, many years and from a materials standpoint they are considered good for potable water applications.
The valves are certified to NSF/ANSI-372 certification for low lead content. https://support.boshart.com/is-nsf-372-the-same-as-nsf-61
The process of obtaining NSF/ANSI-61 certification on the stainless steel valves is underway.
CAUTION: If NSF-61 is mandated these 17CVSS Series Check Valves will not meet the criteria and will not be a suitable option! Until we have the formal documentation, it is crucial that the installer and / or end user check with local jurisdictions to make sure that the stainless product meets and exceeds all the applicable plumbing and water well construction codes which are applicable in the geographic area in which the product will be installed. Code requirement can vary from one jurisdiction to the next, therefore Boshart cannot provide a definite answer to this question.
IMPORTANT: Beyond the code requirements, the Authority Having Jurisdiction (AHJ) over the project could potentially deny the use of product that meets all code requirements; however, they cannot allow product to be used that do not meet all the applicable codes. It is always best practice to verify the certification requirements with the inspector and AHJ.
Material Selection:
NL Brass (No-Lead Yellow Brass) - We do not recommend the use of 17YBCV yellow brass valves in highly corrosive environment such as direct burial or for down the well application, especially in installations where water quality is questionable. Yellow brasses (regardless of make / brand) are susceptible to dezincification corrosion. For this reason, if the check valve is going to be used in a pipe column down the well copper / zinc brass alloys are not a suitable option.
NL Bronze (No-Lead Red Brass) - 17CV series are a great option since Bronze (aka red brasses) having less than 15% zinc content are also immune dezincification corrosion and will last in corrosive environments.
Are products certified to ANSI/NSF-372 truly No-Lead (NL) or Lead-Free (LF)?
https://support.boshart.com/are-products-certified-to-ansi/nsf-372-truly-no-lead-nl-or-lead-free-lf
The answer is both YES and NO. It depends entirely on the material from which the product is manufactured. Very confusing to say the least! In this article we will explain why the misleading NL (No-Lead) or LF (Lead-Free) terminology is commonly used across the plumbing industry in both the U.S.A. and Canada.
304 Stainless Steel (Austenitic stainless steel) - The 17CVSS series 304SS check valves, currently do not have third party NSF/ANSI-61 certification at this time, however we are working on the certification application to obtain the NSF-61 certification on the stainless steel check valves (no firm date for completion available at this time). Austenitic stainless steel has excellent corrosion resistance and formability, high toughness, is 100% lead free, and is impervious to dezincification corrosion. An excellent choice all around, and highly recommended by Boshart.
What if I want to use Stainless Steel and NSF/ANSI-61 Certification is a requirement?
No problem! Until the 17CVSS has been officially certified, Boshart can supply fully compliant 316 SS check valves for projects where third party NSF/ANSI-61 certified product is mandated, we offer high quality FLOMATIC brand valves, links to the common options are copied below 80SS / 100SS (316 Stainless Steel) or the model 80E or 100E (NL Bronze).
https://www.flomatic.com/valves/check-valves/unleaded-bronze/80e/
https://www.flomatic.com/valves/check-valves/unleaded-bronze/100e/
https://www.flomatic.com/valves/check-valves/stainless-steel/80ss-100ss/
WARNING: It is the responsibility of the qualified system designer, AHJ (Authority Having Jurisdiction) and the installer to make sure the products used in any installation meet or exceed all the applicable national and / or local plumbing, building and water well construction code requirements. All liabilities due to misuse of the product are assumed by the installer / end user. It is their responsibility to make sure installations meet all the applicable National and or Local codes in the area, and materials and products are approved by the AHJ over the project.
Additional resources:
https://support.boshart.com/do-i-need-more-than-one-check-valve-in-a-submersible-pump-system
https://www.flomatic.com/news/submersible-check-valves-installation-when-where-why/
https://support.boshart.com/how-to-install-a-submersible-pump-check-valve