Education Report

Haig Demergian, PE, CPD, FASPE
Chairman Education Committee
December 2017

WPC Research Data Base

World Plumbing Council (WPC) announced that the Research Data Base is available on website, for review by interested parties.

WPC is an international organization formed to promote word wide, the new research and accomplishments of new technologies of plumbing industry. The main reason for this program is to inform interested parties of the ongoing research and the results of new technologies applied to various plumbing issues. This program will help researchers to know what projects are already completed and what other projects are still in the testing phase. It is evident that this program will reduce duplication of the research efforts.

In the past the same research was done simultaneous in different Countries without the knowledge of the research under way in another Country.

This Data Research Base will provide information of various research projects across the world. To review this Research Data Base, visit WPC home page, and click on “Research”.



One Member’s Opinion



  1. Water definitions and qualities.

Water chemical formula is H2O. In the liquid state water is a transparent and nearly a colorless substance. Water is an excellent solvent. Every where water flows, either to the ground, thru the air, or thru our bodies, it moves valuable chemicals, That is why water is called “The Universal Solvent”. Water is capable to dissolve more substances than any other liquid.

Water is the only substance which can be found on earth on all physical states: solid (ice), liquid (lakes, rivers, oceans) and vapors (clouds). But we will not find any place on this earth, pure water H2O. Water, as an excellent solvent, will always contain a combination of minerals, gases, suspended particles, etc.

Water is an essential substance required for the life of all vegetation, animal world, and population. Without water all plants, trees and all vegetation, all animals and entire population and any form of life, will not survive.

Fortunately, there is plenty of water on earth. 71% of earth surface is covered by water. Only 2.5% of this water is considered fresh water. Approximately 70% of fresh water used by humans is used for agriculture. The total volume of water on this planet is estimated at 1,338,000,000 Km cube.

  1. Water cycle.

Water on earth moves continuously and this is known as water cycle. Water from the surface of all oceans, rivers and lakes evaporates and forms clouds. Also, plants and trees transpires and become clouds. The clouds precipitates over the land, which produces rains and the runoff reaches the seas. And the cycle continues. During this cycle a lot of minerals are moving together with the water.

In addition natural water will also be populated by various viruses, bacteria and microbes which are plenty on the ground and above ground where natural water is flowing. To study the influences of water transmitted diseases over living organisms and plants, a group was organized and was  named Microbiology.

Microbiology, as a science is a relatively new, which started to study bacteria, viruses and microbial life at the beginning of 20th Century, after Dr. Louis  Pasteur, Dr. Robert Koch and others, demonstrated to academicians and scientific organizations, that all illnesses are the result of activities of viruses or microbes or bacteria.

Viruses and microbes and bacteria are the first form of life on this earth. We are fortunate that they left behind fossils. Based upon studies of ancient sites it is estimated that bacteria, viruses and microbes were present about 3.5 billion years ago. Compared with fossils of  “homo sapiens” (ancestors of humans) whose fossils appeared approximately 200,000 years ago, shows the viruses and microbes and bacteria had plenty of time to develop and specialize.

Today we have tens of thousands species of highly specialized bacteria, viruses and microbes living in the water, air, our bodies, underground and elsewhere. This makes the work of microbiologists to find a vaccine, very difficult and time consuming.

For instance: common cold is produced by viruses which enters our body when we inhale. Specialized laboratories work hard to discover a vaccine to be administrated to the population to help our immune system to destroy the virus Discovery of a vaccine, testing it, approvals, packaging and make it available to the population takes an average of 3 to 5 years. When the next epidemic of flu comes, the vaccine produced, is already obsolete, because the new virus is “mutated” and  the vaccine is ineffective.

The main reasons they survived for so long is that viruses and bacteria multiply exponentially, asexually and they poses the capacity to “mutate” to resist extreme  environmental changes.

I am not a doctor or microbiologist, and my education and experience is in engineering. But I am fascinated and interested, to learn more about bacteria, viruses and microbes. As a Plumbing engineer, I designed many potable hot and cold water distribution  systems for various structures. The subject of transmission of viruses, bacteria and microbes in potable water systems, was and is a prime concern of engineering societies as ASHRAE, ASPE and others. I am also concerned, because Legionella outbreaks are on the rise. CDC reports that about 5,000 cases of Legionella are reported each year in USA. Some of these cases results in patients who for hot water and do not survive.

Recent published documents (see ANSI/ ASHRAE 188- 2015 Legionnelosis risk management) suggest that transmission of viruses, bacteria and microbes in potable water systems can be solved primarily by proper design of water systems and proper maintenance. This is a huge responsibility and liability for Plumbing engineers, designers, contractors and owners. Without specific design directions, ANSI/ASHRAE Standard 188-2015, is very confusing and will be a good field of litigation, for lawyers.

It also will require additional design fee, and increase the cost of construction, to comply with all the recommendations included in ANSI/ASHRAE Standard 188-2015, especially for construction of health care facilities.

Center for the Disease Control (CDC) describes Legionella Pneumophila as respiratory disease caused by a bacteria called Legionella. The bacteria were discovered after a 1976 outbreak in a Philadelphia Convention center of the American Legion. A total of 127 were affected from a type of pneumonia, and 12 died. More information about Legionella history and outbreaks, review

I read several proposed solutions to limit or stop the growth of Legionella bacteria in plumbing systems. Some of them suggest temporarily increasing the hot water temperature to 160°F and re-circulating the super hot water, throughout the system. This is supposed to kill all the bacteria in the plumbing system , but in the mean time, will make the hot water system subject to scalding especially young children, older persons and people with disabilities. Unfortunately, recirculation of super hot water will not reach the entire piping system, for existing buildings, which were installed with a lot of “dead ends”.

All vertical branches serving plumbing fixtures will not be affected by the super hot water. These “dead ends” will contain enough live bacteria to start new colonies of millions bacteria. In addition, since plumbing systems are “open systems”, every time a plumbing fixture is used, new bacteria will be admitted in the system from municipal water system. We know that municipal potable water is allowed, by EPA Standards, to have small percentage of Ecoli and other bacteria. If temporary increase in water temperature will be the procedure to destroy bacteria, then each fixture using hot water must be equipped with a “point of use ”thermostatic mixing valve”, to limit delivery of hot water to the fixture at 105°F to 110°F. Also, the water heater, or other equipment providing hot water, shall be capable to deliver water at 160°F. Another suggestion to control bacteria, is to temporarily add additional chlorine, and recirculate in the plumbing system of super chlorinated water. The situation with the “dead ends” mentioned above will apply, and the intention to kill all bacteria will not work.

Definition of potable water

The big puzzle in my mind is that the acceptable definition of potable water to be furnished by water purveyors is not pure H2O. The EPA definition of potable water allows small amounts of various minerals and salts, plus a small amount of E coli (which is a species of bacteria). For instance, potable water, delivered by Los Angeles Department of Water and Power (DWP), after all water treatments, includes various quantities of chemicals such as: carbonates, bromate, fluoride, halo acetic acids, lead, trihalomethanes, and coliform bacteria among others.

Exponential growth of bacteria

All bacteria reproduce by exponential, asexual reproduction, which results in cell division. We know that single cell bacteria have extremely rapid way to multiply. For instance, one bacterium will divide, and now we have two. These two will divide again and we have four. Four will divide again and we have eighth. This is called exponential growth. This process of multiplication repeats, and in a matter of few hours the new colony of millions of bacteria is formed.

In the lab the growth of bacteria was monitored, and in the average, they found several phases:

Lag phase. Bacteria initially adjust to the new environment (test tube or dish). About 8 hours.

Exponential phase. Bacteria start dividing. About 18 hours.

Stationary phase. When the space becomes too small or the nutrition is exhausted, bacteria stops growing. About 5 hours.

Death phase. Eventually bacteria show loss of viability and dies in about 10 hours.

Water piping for HVAC

Water piping serving HVAC projects (hot water and chilled water) is a “closed system”, where the water filled at the beginning, is continuously re-circulated. Make-up water, in small quantities, is added to compensate water lost due to leakage of the system. The water is maintained at temperatures of 180-200°F, for hot water which kills bacteria and 40-45°F for chilled water, which do not allow bacteria to multiply. Special chemicals (bactericides) can be added to the system to keep bacteria from multiplication or kill them.

Another system is the water from the cooling tower, (condensing water), is an exception. This water system is an “open system” because condensing water  becomes  in contact with outside air and  will add more bacteria and viruses, when the cooling tower water runs thru the cooling tower.

A recent article published in Water Conditioning and Purification of September 2017 prepared by Timothy Keister  CWT, FAIC, entitled “Using Softened Water for Cooling Towers” makes the argument for the benefits of using soft water for Cooling Towers.(Very interesting article with diagrams and calculations to justify his proposal)

Potable water piping.

Potable water piping serving Plumbing projects is an “open system”, where every time a faucet is open for flushing a Lavatory, WC, Sink, Urinal, etc., a fresh quantity of municipal water is admitted into the system. This fresh water admits in the Plumbing systems: Salts, impurities and bacteria allowable in the municipal potable water  systems.

Therefore, the proposed procedures to prevent growth of bacteria for HVAC projects must be different than the procedures for Plumbing projects.

Some bacteria produce a “biofilm”, which will deposit inside the pipes, and will protect other bacteria covered by “biofilm” from being destroyed by biocides or temporary super hot water (160°F) circulated occasionally.

The way I see it, the water entering the building from municipal piping should be free of any bacteria, viruses or microbes and to have minimal residual salts, minerals or other chemical compounds. For instance: minerals, as calcium carbonate (CO3Ca) or magnesium carbonate (CO3Mg), will eventually deposits inside the pipes and equipment, will produce a scale, which will increase the friction loss (more energy to move the water), will corrode the pipe and will be an excellent place for bacterial development. Various USA zones contain water with high concentration of these compounds (hard water). Removing them from water entering the building will save a lot on energy and maintenance. This is beneficial for Plumbing and HVAC systems.

Plumbing water piping disinfection.

Pipes and materials used for potable water piping systems shall be certified to comply with NSF (National Sanitation Foundation) Standard 61.

Piping shall be delivered at site with caps on all open ends and stored to prevent contamination with foreign particles as sand, dust, rust, etc.

At the end of each working day, all open pipe ends shall be capped to prevent contamination.

A thorough flushing and disinfection of plumbing piping system, in accordance with AWWA C 651 or as required by Code, with chlorine or other bactericides, and final flushing must be performed before plumbing piping is accepted to be used by the occupants.

After disinfection, samples of water shall be collected and submitted to a Certified Lab to determine the concentration of bacteria. If bacteria are detected, the procedure shall be repeated.

Also, water entering the building from municipal piping, should have a device, for instance a UV (Ultra Violet) generator,  to destroy all bacteria and viruses for potable water, supplied to the building occupants.

Potable water systems designed and installed based upon traditional practices include uncounted number of “dead ends”, serving plumbing fixtures, water hammer arrestors, flushometer valves, equipment, etc.  Bacteria once admitted in the Plumbing Systems will be very difficult, if not impossible, to destroy them.

A recent study performed in a hospital in Sherbrooke, Canada determined that heat exchangers, installed to conserve energy, promoted growth of Legionella in the hot water supply. The study appeared in the Journal of the Society for Healthcare Epidemiology of America. The conclusion was: Remove heat exchangers. Reason: “No energy or water savings are worth a human life”

Water Management Plan (WMP)

ANSI/ASHRAE Standard 188-2015 requires that all buildings, except single family, shall have a WMP. We should differentiate WMP for existing buildings from WMP for new buildings. The reason is that existing building’s plumbing systems were designed and installed with no special attention to WMP.

New building’s plumbing systems should be designed and installed to comply with new rules to restrict or limit exponential multiplication of bacteria or other pathogens in plumbing systems. Building Owners and Managers, as responsible parties, should have a plumbing system which can be monitored and disinfected, if necessary. This can be accomplished by proper design.

Smart loop hot water recirculation system.

Recently I read about a relatively new system for recirculation of hot water for large buildings, called “smart loop system”, offered by Viega, as part of pro press piping system. The system includes hot water recirculation pipe (HWR), inside hot water (HW), and a special “double drop elbow”, which eliminates “dead ends” for supplying  water to fixtures.

Fundamental criteria to combat micro organisms in potable water piping.

Prevention is preferable to cure.

Micro organisms have an extraordinary fast way to multiply, and mutate to be resistant to antibiotics or other medications we invent.

Remove or destroy any micro organisms, before potable water enters building piping distribution systems.

Remove salts and minerals from water supplied from municipal pipes.

Some of these minerals will eventually precipitate and deposit inside pipes and equipment, and will be an excellent place for micro organisms to hide and multiply. This can be  accomplished by using water softeners or other procedures.

Best Available Technology (BAT)

The fight against Legionella just started. Appears that bacteria are a step ahead of our technology to destroy them, and protect our population. Therefore, in the near future, we should expect more outbreaks of Legionella disease. In the mean time we should adjust and continue our fight, by using revised and improved BAT.

Request for review and comments.

I prepared this document, based upon my limited knowledge of all equipment and devices available to combat multiplication of micro organisms in potable water systems.

It is agreed by all authorities that micro organisms and chemicals in potable water systems are detrimental to health and safety of population. As professionals, we should use all existing and new technologies, to prevent spreading diseases and allowing deposits of scale on pipes and equipment of potable water systems.

All These suggestions, really will require a new approach for designing potable water systems systems. We should not expect that a Plumbing Engineer/Designer alone will come up with a proper design of improved Plumbing system.

This complex task, calls for collaborative effort of many engineers, contractors, and manufacturers. ASPE is the organization which should take the lead.

Please call or write me with your comments and suggestions.