During the last few months, I have heard a number of debates about the use of the term “potable water” versus “drinking water.” What has been interesting is everyone actively involved in the plumbing profession insists on using the term “potable water.” While others think that “drinking water” is more understood by the general public.

To date, potable water has won out. Being a purest, I have supported the use of the term potable water, which in the plumbing profession is drinking water. The plumbing codes have defined potable water as water safe to drink.

I was curious as to the origins of the term potable, so I did some checking on word origins. Apparently, the word potable dates back to the 1500s. It has Latin origins: pōtābilis means drinkable. Also, in Latin pōtā(re) means to drink. This reminded me how my mother always thought that I should take Latin so I would do better in English. I always told her that Latin is a dead language and why waste my time. Maybe she was right.

The discussion on potable water relates to a number of standards that are currently being developed or updated. IAPMO has a new manual being established on the standard practice for opening and closing buildings. During the pandemic, there were many buildings that shut down for months. Thus, the plumbing systems sat unused for a long period of time. When employees are called back would the water be potable?

The IAPMO document is entitled, “The Manual of Recommended Practice.” The manual is being developed through the consensus process; however, it is not intended to be a standard. The manual will be a wonderful document that plumbing engineers can use to assist their clients. It can also be used to answer questions that building owners may have regarding the use of their building.

In addition to requirements on potable water systems, the manual also has provisions for non-potable water systems and hydronic systems. The information on cooling towers and Legionella is also very good.

You can review the draft of the manual by downloading it from the IAPMO website, www.iapmo.org.

The standards that regulate certain aspects of the quality of potable water are NSF 60, NSF 61 and ASHRAE 514. NSF 60 and 61 have been a part of the plumbing profession for more than 30 years. Plumbing engineers have long been requiring compliance with NSF 61 for any material used in potable water systems. NSF 60 is the standard that lists the products that can be directly added to the potable water system, namely, chemicals used to maintain the potability of the water.

Many have considered NSF 60 to be a standard used by municipal water treatment facilities. With an increased use of local or building water treatment systems, NSF 60 comes into play. There are a number of treatment systems that add chemicals directly to the potable water system. The chemicals and the dosage need to be in compliance with NSF 60.

I encountered a recent building treatment system with chemicals being added. The chemicals being provided were not listed in NSF 60. Furthermore, upon investigation, the company supplying the chemicals didn’t even know that NSF 60 existed. I considered this dangerous, since third-party certification to a consensus standard assures us that the use of the chemicals is safe.

The other NSF standard, NSF 61, has become debatable for hot water applications. There are some in the profession who believe hot water is not used for drinking water. I will not debate that issue, other than to say that many plumbing codes, including the International Plumbing Code and the Uniform Plumbing Code, require hot water piping materials to comply with NSF 61.

One of the issues recently raised has been the application of NSF 61 for materials used in hot water recirculation systems. NSF 61 is actually based on a single pass through the piping. With a recirculation system, the water passes through the piping many times. The engineering community needs to realize that this application has not been addressed yet.

The last standard mentioned is ASHRAE 514. This standard is currently under development. There was recently an advisory draft posted for review by ASHRAE. This resulted in many comments to the draft.

ASHRAE 514 is identified as a new standard to regulate the quality of water. It started as an offshoot of ASHRAE 188. As most engineers will recognize, ASHRAE 188 is the standard on Legionella. The problem that has arisen with ASHRAE 188 is many consider the standard to be a risk management standard. As a result, many engineers view it as a document for building owners to use, not the engineering profession. Of course, engineers are always involved in doing risk management as a part of their evaluation of building systems. Hence, the standard can be used by engineers. It merely becomes difficult to reference the standard in the plumbing codes.

ASHRAE 514 will contain provisions for Legionella prevention, but it will also include provisions for other possible contaminants that can be present in the potable water system. Again, the debate between potable water and drinking water. Rather than being identified as a risk management standard, ASHRAE 514 will be identified as a standard that can be adopted and enforced through the plumbing codes.

While ASHRAE 514 sounds very promising, which it is, the standard will not be published for at least another two years. That it how long the consensus process takes with such a complex standard.

Having been a member of SSP 514, the committee developing ASHRAE 514, I can report that the progress has been excellent. While I may not agree with some of the provisions, that is a part of the consensus process. You add your comments, but listen to others. In the end, the document will contain very good provisions that the engineering profession can use.

Protection of potable water has always been the most important aspect of a plumbing code. That level of protection is constantly being reviewed, with many new requirements being developed to guarantee the safety of potable (not drinking) water.