2012 May-June

Responsibilities in preventing microbiological growth in plumbing systems by Abigail Cantor P.E. (Chemical Engineer) This article describes the responsibilities in preventing microbiological growth from occurring in plumbing systems.  Those responsibilities are shared by the Plumbing Designer, the Building Contractor, the Municipal Water Utility Manager, and the Property Owner. The Plumbing Designer The prevention of microbiological Read more

Responsibilities in preventing microbiological growth in plumbing systems
by Abigail Cantor P.E. (Chemical Engineer)

This article describes the responsibilities in preventing microbiological growth from occurring in plumbing systems.  Those responsibilities are shared by the Plumbing Designer, the Building Contractor, the Municipal Water Utility Manager, and the Property Owner.

The Plumbing Designer

The prevention of microbiological growth in plumbing systems starts with the plumbing designer.  Two new design requirements must be met in order to prevent microbiological growth – the volume of water residing on-site must be minimized and the surface area that the water contacts must be minimized.  These design requirements must be balanced against the property owner’s list of desired plumbing fixtures and the plumbing code’s design criteria.

Considering the Number of Fixtures and Pipe Sizes

The property owner may have a long list of desired plumbing fixtures and showers with multiple sprays.  The plumbing code will base the size of the piping on the number of fixtures that can possibly operate at the same time.  The property owner needs to understand that there is a trade-off between having extra plumbing fixtures versus minimizing the volume of water stored in the piping.  The use of diverter valves as well as the property owner’s acceptance of fewer fixtures may assist in keeping pipe sizes smaller.

Considering Water Conservation Fixtures

Water conservation fixtures are becoming a necessity in some areas where drinking water resources are scarce.  With both new plumbing systems and the modification of existing plumbing systems, the lower water usage must be considered and the on-site storage of water be reduced accordingly.

Considering Tubs

The property owner’s selection of bath tubs and hot tubs will greatly influence the quantity of hot water that needs to be prepared and stored on-site.  The property owner needs to understand the trade-off between the number of tubs and the filling rate of each tub versus minimizing the volume of water stored on-site.

Tankless water heaters can be used to assist in lowering the volume of hot water that needs to be stored.  Acceptance of lower filling rates by the property owner will also help to lower the volume of hot water storage.

Considering Water Softening

With hard water, water softening is required before sending water into a hot water system.  Calcium carbonate from hard water will scale up the heating surfaces in the hot water system which will, in turn, increase the quantity of energy and the cost to heat the water.  The life of the hot water heating equipment will also be reduced with the build-up of scale.

However, water softeners increase both the volume of water stored and the surface area that the water is exposed to on-site.  They can become incubators for microorganisms.  If less hot water is required, then less water needs to be softened and the smaller the softener tank.  Again, the property owner’s acceptance of lower filling rates for tubs will lower the hot water volume requirement.

In addition, cold water does not need to be softened except in a few specific cases.  Water softeners can be smaller when only the water for the hot water system is softened.

Water softeners can also be outfitted with the dosing of chlorine and other biofilm-fighting chemicals to the brine tank so that disinfection of the media inside the softener tank can occur routinely and prevent the development of biofilms inside the tank.

Considering Other Water Treatment

A previous article pointed out that water should not be treated on-site unless absolutely necessary.  The article listed possible contaminants in water and steps to take in deciding whether or not removal of certain contaminants is necessary.

For every treatment device, water volume and surface area is increased in the plumbing system.  Each device must have a means of routine cleaning and disinfection, as was discussed with water softeners, in order to prevent them from becoming incubators for microorganisms and inoculating the downstream piping.


Considering Chemical Dosing into Piping

Water softening and other on-site water treatment devices can remove existing disinfection from the water.  Long residence times for water such as in hot water storage tanks also deplete the disinfection in the water.  Designers of commercial buildings where large volumes of water are required need to consider re-injecting chlorine or other biofilm-fighting chemicals approved for potable water after water treatment devices and before storage tanks.  A previous article described chemical dosing systems.

Some property owners, such as those with private wells, do not want to introduce disinfection because of its taste and smell in the water.  Disinfection chemicals can also form harmful by-products if dosed incorrectly.  But chemical disinfection, especially chlorine, is the most significant protection against the growth of microorganisms in modern water systems because of its disinfecting power at a reasonable cost and its ability to remain in the water to the far reaches of the plumbing system.

Considering Pipe Flushing Features

If high-volume, complicated plumbing systems are inevitable in a building, automatic pipe flushing should be considered.  Automatic valves can be placed at the ends of long pipe runs to move fresh water through the water line.  Such a valve needs to be slow-opening and closing so that water hammer does not occur as it does with a solenoid valve.  Also, this strategy wastes water which cannot be tolerated in areas where water resources are scarce.  Nevertheless, in some cases, automatic pipe flushing may be the only answer to keeping water fresh on-site.

Considering Sampling Taps

Small valves and faucets are inexpensive to install in pipelines.  Consider installing such taps before and after any water treatment or storage tank in the plumbing system so that water samples can be taken and the quality of water, as it changes throughout the plumbing system, can be monitored.  A previous article described critical locations in plumbing systems where microorganisms can grow.  This can be a guide for locating sampling taps.

The Building Contractor


The growth of microorganisms in plumbing systems begins during the building’s construction period when water pipes are filled with water.  The water usage, at that time, is not what the plumbing system was designed for and the water sits stagnant in the pipes for a long period of time.  Any disinfection in the water is quickly depleted.  Microorganisms can now thrive.  Building contractors should ensure and document that this does not occur on their watch.

Before a project begins, review the plumbing plans for the design features that have been discussed in these articles.  Every pipe run, water treatment device, and water storage tank has the potential for microbiological growth during the construction period.  Is there a way to monitor, flush, and disinfect each plumbing system feature during the construction period?  If not, work with the plumbing designer to provide the means to do so.

Before filling new pipes with water, make sure that they have been cleaned of debris and disinfected.

After filling new pipes with water, begin monitoring for and documenting chlorine concentration routinely and frequently.  A previous article describes how to do this with a relatively inexpensive field test kit.

Less frequently, monitor for microbiological activity.  A previous article described how to do this with water samples for Heterotrophic Plate Count (HPC) analysis.  Since that article was written, a better test has become commercially available.  It is a test for ATP and is described in a sidebar to this article.

Run treatment devices through their cleaning cycles on a routine basis during construction and refresh the water in piping and tanks.

The amount of plumbing system flushing can be reduced by dosing the water system with chlorine and biofilm-fighting chemicals used in potable water systems.  (See a second sidebar for a description of chemicals that can be used.)

Strategies to carry out these tasks in an economical fashion during construction need to be developed.  This is a new concept for the building industry, but it can and must be done based on the current knowledge about microbiological growth in water systems.

The Municipal Water Utility Manager


The role that microorganisms play in water systems is a new topic in the drinking water industry as it is in the plumbing industry.  Municipal water utility managers are just becoming aware that microorganisms and their biofilms can help to transfer piping metals like lead, copper, and iron to water.

Municipal water utility managers need to ensure and document that the water throughout the water distribution system stays properly disinfected and that microbiological activity is low.   Throughout the distribution system, managers need to:

  • Monitoring for disinfection and microbiological activity
  • Minimize water residence time (water age)
  • Ensure a proper disinfection residual
  • Perform uni-directional flushing on water mains to properly clean piping

Managers might want to refer to a Water Research Foundation report that demonstrates techniques to control water quality at the consumers’ taps (Project 4286: Distribution System Water Quality Control Demonstration).

Ironically, because of modern plumbing design practices, the growth of microorganisms can occur whether or not there is a high microbiological activity in the water entering a building.  However, water utility personnel should document that the municipal system did not contribute significantly to any building’s plumbing problem.

The Property Owner


Property owners need to understand the dilemmas in designing and installing modern plumbing systems as have been discussed in these articles.  That way, they can make better decisions in planning their buildings’ plumbing systems.

If a property owner uses a private well instead of municipal system water, that person must take on the responsibilities of a water utility manager.  They need to know what contaminants should be removed from the water and the best method of removal.  They also need to consider how to keep the water and the system disinfected.  They must monitor for disinfection and microbiological activity and ensure that their water system is operating safely.



Preventing the growth of microorganisms in plumbing systems is a new reality for modern plumbing systems.  There has not been a lot of experience in designing systems with minimal volume and surface area while still utilizing the new plumbing fixtures that are available today.  But, the plumbing industry can start by being aware of the microbiological growth issues and design dilemmas.  Eventually, people in the plumbing and construction industry will figure out how to accomplish this task economically and efficiently.

This pushes people away from techniques that they have always used and what they have always known to be true.  But, the industry must move in this direction or else the future will be filled with ruined plumbing systems in new buildings, angry property owners, and liability lawsuits for plumbing and building contractors.

This series of articles does not provide all the answers needed to tackle this problem; they were written to raise awareness of the problem and to encourage the plumbing profession to consider the repercussions of the volume of water stored on-site and the surface area that the water is exposed to.  The growth of microorganisms in plumbing systems can be prevented with everyone’s participation.


A New Method of Testing for Microbiological Activity


In a previous article, a method of measuring microbiological activity in water was presented.  It was a method to measure the number of heterotrophic bacteria colonies that can grow from a water sample (HPC analysis).  But, there are other types of bacteria in water besides heterotrophs.  Nevertheless, the HPC analysis was used because it was the only economical and commercially available test.

A new type of test now meets the economics of the HPC analysis.  It is a test for adenosine triphosphate (ATP), the energy molecule found in living organisms.  This test will measure the presence of any type of living organism in the water sample, not just heterotrophic bacteria.

Unfortunately, there are only a few laboratories and professors that have the equipment to run this test.  For example, only one small laboratory in Wisconsin can run the ATP test.  Nevertheless, it is worthwhile to pursue the use of this test by inquiring at commercial laboratories and by contacting major manufacturers of the equipment (http://www.luminultra.com/Industry-Applications/water-treatment.html).

New Chemicals to Clean Out Biofilms

Chlorine is the most common chemical used for disinfection of drinking water.  The chemical is effective in preventing biofilms from forming.  However, once the biofilms have formed, it is difficult for the chlorine to penetrate the biofilm and remove it from surfaces.  In addition, many modern plumbing materials cannot be exposed to high concentrations of chlorine, so dosages that can be used are limited.

There are new chemicals on the market that can penetrate and destroy biofilms.  For use in drinking water, the chemical must be approved by NSF International (http://nsf.org) as an acceptable additive.  When determining new chemicals to use for biofilm removal, look for the NSF approval and follow-up on references of organizations that have used the product.

Promoting Energy Efficiency with luxury by Lori Henderson We all know we should eat healthier foods, protect our- selves from the harmful rays of the Florida sun, exercise every day, and turn off the shower when we’re done rinsing. But why do so many Florida residents resist doing things that are good for them?I’m sure Read more

Promoting Energy Efficiency with luxury
by Lori Henderson

We all know we should eat healthier foods, protect our- selves from the harmful rays of the Florida sun, exercise every day, and turn off the shower when we’re done rinsing. But why do so many Florida residents resist doing things that are good for them?I’m sure that inertia is a big reason many Floridians avoid making changes in their life styles and personal habits. But as a plumbing professional, you have opportunities every day to talk with your customers about advancements in energy effi- ciency. After all, a few simple changes can help your cus- tomers beautify their homes, maintain the “wow” factor, and save money by conserving resources. Now is the time to take advantage of this opportunity to educate your customers and build your plumbing business.As you know, there are many ways you can help your cus- tomers upgrade their current homes to use water more effi- ciently without losing their favorite design elements, affecting their lifestyles, or breaking the bank.Some of you out there are already doing your part, and we thank you for that! The reader I am addressing is the contrac- tor who doesn’t know what to say to the customer or thinks these new options are just too expensive for today’s market.Through this article we will explore the different options and resources for your residential and commercial customers to conserve water without sacrificing design and luxury.

(Left) American Standard’s Reliant 3 LifeStyle collection: Cadet 3 HET and Reliant 3 shower.
(Above) Watermark’s Titanium faucet.There are many ways you advise your customers about upgrading their current residence and promote a healthier life style and elevate the design of your home. We are going to focus on a few out of the many options, including:

  • Changing out an older toilet for a high-efficiency toilet (HET).
  • Replacing the old showerhead, faucet, or body sprays with WaterSense-certified selections.
  • Selecting attractive, recycled materials for sinks and vanities.
  • Replacing a water heater with a heat pump unit.

Discussing these types of options with your customers pro- vides an ideal opportunity to generate new business. After all, a homeowner who starts off wanting to add new water-saving faucets might eventually decide to redo the entire bath.

Advantages of HETs

Let’s start by examining the benefits of changing out a customer’s toilet for an HET.  As a plumbing professional, you know there have been enormous advancements in toilet technology in the past 20 years, going from 5 gallons down to 3.5 gallons down again to 1.6 gallons and now down to 1.28 gallons per flush (gpf).  However, your customers are probably not aware of these changes and need someone to explain things to them.  They may also have misconceptions about HETs that make them hesitate to try it. Here is an opportunity to explain the advances in technology and the benefits to upgrading the bath.

After all, many of the toilets we have available to us today flush better than the antiquated 5gpf toilets.  In 2003 MaP (maximum performance) testing for toilets was developed. A toilet that is MaP approved must flush 350 grams of solid waste and tests up to 1,000 grams of solid waste (over 2 pounds). Now that we are able to rate the toilet’s performance, the best toilets strive to function at or over the 1000 gram mark while using a 1.28gpf.

Once a company has mastered HET performance the next focus is the style. In the high-performance toilet category, styles ranging from traditional to contemporary and everything in between are now a must in all price points.  Since there are many options available, try to narrow down what features are most important to your customer.  Luxury features can add benefits a homeowner may never have considered, such as:

• Higher seats, designed at the same height as if you were sitting on a chair.

• Enclosed trapways

• A smooth side to cover the dust catching rolls on the base of the toilet

• Dual flush, one for liquid and one for solids to help save even more water

• Antibacterial agents, infused or baked into the glaze to help protect against germs

• Bidets

• Heated toilet seats

• Water cleaning functions built into the toilet.

Tell the homeowner she doesn’t have to sit on a cold toilet seat and watch her eyes light up. And with slow closing toilet seats, slamming the seat is a thing of the past.  These are just a few of the features available while your customer is getting the best performance and saving water with each flush!


Now for the shower

Let’s talk about the shower next. About 17 percent of residential indoor water use in the United States is from showering.  This adds up to more than 1.2 trillion gallons of fresh water each year nationwide, according to the U.S. Environmental Protection Agency (EPA).

When you replace your customer’s older inefficient showerhead, handshower or body spray with a WaterSense model, there are potentially big savings on the water bill and on the energy bill as well, since there will be less demand on the water heater.

WaterSense provides consumers with the confidence these products will work effectively and efficiently with a 20 percent or greater water savings.  Think about this: If one in every 10 homes in America installed a WaterSense faucet or showerhead, it could save 6 billion gallons of water per year!

A good showerhead can make or break the shower experience. No one wants to end up with soap in our hair or a trickle of water coming out to rinse with.  Performance is the most important feature of the showerhead or faucet so you want to make sure the model has innovative function that qualifies it as WaterSense®.  If the model has the option for a low-flow aerator to reduce water flow it probably isn’t the best function.  The best models have a mechanism or function that allows the water to flow at a lower rate while providing the same experience as a high flow model.

Many manufacturers have introduced innovative showerheads and faucets that are WaterSense certified while maintaining superior function.  When helping your customer search for a new showerhead, look for multiple spray patterns, adjustable flow rates, non-removable flow restrictors and rubber nozzles.  Many shower arms are available to add height and adjustability to the showerhead as well.

Faucets are available in a variety of styles, finishes, shapes, construction and function.  Find a WaterSense labeled faucet with quality construction features, including ceramic cartridges, cast brass construction, lifetime warranties and brass drains. Then let the customer’s preferred style be your guide!


Selecting recycled materials

In addition to conserving water, there are other simple ways for a homeowner to save energy. Many manufacturers now create products with reclaimed, recycled, and sustainable materials that require less energy and reduce the drain on our natural resources.  Many of the designs created from these materials are unique and hand crafted. Imagine a vanity for the bathroom created from wine-making oak barrels or made from the sustainable properties of bamboo.  A kitchen sink today could be made up of reclaimed copper that kills bacteria or recycled stainless steel. Each piece could be one-of-a-kind, adding a piece of artwork to the home while being ecologically friendly.


Consider heat pumps

Here is a great idea for helping the homeowner: Install an Energy Star® rated electric heat pump that is more than twice as efficient as a standard electric water heater.  The hybrid electric heat pump water heaters will heat the water while cooling the air surrounding the unit.  Electric heat pumps use the surrounding heat of the room to heat the water while dehumidifying and cooling the air. This averages about $360 dollars a year in energy savings  – before you install all of the WaterSense products – according to the Department of Energy. Imagine a garage with cool air or directing that cool air up into the attic to help cool the entire home!


Rebates add to affordability

When comparing costs for these energy-saving upgrades, be sure to tell you customers about rebates that can help offset the costs to make these important changes. Federal, state and local rebates are now available in most locations.  The rebates offer substantial savings from $100 on HET to $650 on heat pumps to $1 per square foot on a whole energy efficient home.

Some examples of products for which rebates are available, include water heaters, heat pumps, central air conditioners, building insulation, windows, roofs, solar screen, window film, heat pump water heater, tankless water heaters, pool pumps, in-ground irrigation, cooking range, dryer, solar water heat, photovoltaics, washers, toilets, showerheads and more.

Here are two websites that offer information on rebates:

• Federal – http://www.dsireusa.org/incentives/index.cfm?State=US&ee=1&re=1

• State – http://www.dsireusa.org/incentives/index.cfm?getRE=1?re=undefined&ee=1&spv=0&st=0&srp=1&state=FL

Clearly, you can benefit from helping your customers understand the many “green” options available that will allow them to conserve our natural resources and enhance their homes with beautiful designs.  Good luck!


We are back with another article and this time we will look at water quality and its effect on water heaters and boilers. BOILERS Boilers are typically closed loop systems where fresh water is used to fill the system but the same fluid is used over and over again. After a system fill, very small Read more

We are back with another article and this time we will look at water quality and its effect on water heaters and boilers.


Boilers are typically closed loop systems where fresh water is used to fill the system but the same fluid is used over and over again. After a system fill, very small amounts of fresh water will enter to maintain system pressure. Chemicals are added to inhibit corrosion and prevent freezing. The dissolved oxygen, calcium and other minerals will precipitate or “fall out” of the heating fluid. They only become present if fresh water is allowed to re-enter the closed loop system.

For instance, I experienced a scaled up heat exchanger on a properly installed closed loop boiler. After further inspection of the closed loop fluid it was found to be untreated fresh water.  The maintenance crew had been using a boiler drain valve to extract heating hot water for cleaning purposes. This occurred every day where they would fill a 5-gallon bucket twice a day. They had access to a Domestic water heating system (right next to the boiler) that resolved their boiler scaling issue.



Water heaters are designed to heat volumes of fresh water up to temperature for domestic and potable uses. The fresh water can contain various minerals and chemicals that will shorten heater life or cause adverse conditions when heated.

Scale build-up is the single most cause of water heater failure and loss of efficiency. The nature of water heater design can be a definitive factor in longevity and overall efficiency but the water conditions are area, utility or site specific. Calcium is present in water and it wants to stick to heating surfaces as it changes from suspension to solids.



Most tank-type water heaters use a ceramic porcelain Glass lining to protect the steel vessel interior from fresh water. The glass lining requires a sacrificial anode to cover and protect any weak spots on the lining. Electrolysis will attack the weakest spot on the lined tank interior and the anode is designed to give itself up to fill that particular spot. Over the life of the heater the anode will sacrifice or “give up” small amounts of its soft metal to protect the lining.

The two metals most commonly used in water heaters for anodes are either Magnesium or Aluminum. These metals are softer than steel and less noble. They can sacrifice themselves prematurely if attacked by the content of the water. These have distinct signs and smells that help to recognize how to deal with such issues.

Here are some common water problems related to water heaters and anode rods:


Hydrogen Sulfide – reaction created by a sulfate-reducing bacteria. It occurs with water that has high sulfur content and it attacks the magnesium anode. It is referred to as “Rotten Egg” smell. Hydrogen Sulfide gas in large quantities can be toxic and explosive.

Hydrogen Sulfide normally can be corrected by changing to an aluminum anode rod after performing a complete chlorination and flush of the tank and piping to kill the bacteria. Some manufacturers specifically use an aluminum anode rod as standard equipment in Florida to avoid the reaction to magnesium.


Aluminum Hydroxide – reaction caused by high pH water. It occurs many times in areas with high chlorine/chloramines in the water supply. Chlorine has a very high pH of 11.7. This reaction forms a jelly-like substance on the anode rod and in the bottom of the tank. It can appear as grey, blue or green beads or gel. The odor produced smells something like week-old trash so it is not something you can tolerate very long!

High pH also means alkaline or scaling so the tank must be flushed out and possibly de-scaled. The reaction is treated with the other viable anode made of magnesium.


Water Softeners – water softeners reduce grains of hardness through a process of ion exchange. Most water softeners exchange sodium (salt) ions with insoluble calcium and magnesium ions. Sodium can increase electrical conductivity and accelerate anode consumption. Use of water softeners warrant monitoring of pH level, conductivity and anode inspection at a regular interval, no less than once a year.


Stagnation – allowing the same water to exist in the tank for long periods of time will result in stagnation. The potential for bacteria increases. This can attack the anode and the results are smelly water and a heater that needs service. Many seasonal residents of Florida will leave their winter homes and forget to drain down their water heater. They typically turn off the power before they leave and the low temperature, stagnated water starts creating the perfect Petri dish. The other application is a larger storage heater that does not get used much, where very little fresh water enters to replenish the stagnated water. A 50 gallon heater on a break room sink is a great example of an over-sized and under-used heater.


Grounding – bad earth grounding can create an electrical potential that will erode the anode at a rapid rate. Once the anode is gone, the steel tank is attacked by the electrolysis.



There is newer technology on water heaters for cathodic protection. Electronic controls can help to implement a non-sacrificial anode. The benefits of such a device are a milestone in tank protection.

The Powered Anode is a titanium rod that is immersed in the top of the heater tank. It can function as a Low Water Cut Off to insure that the tank is full of water. Titanium is a very hard metal, mostly impervious to fresh water and much more noble than steel. It will last longer than the water heater and does not sacrifice itself. So there is no smell that will be generated by this non-sacrificial anode rod.

The electronic controller will send out a micro-DC current to the Titanium rod to offset electrolysis. The electronic controller sends out more micro-DC voltage as the tank lining gets older. At some point, the electronic control cannot put out any more current. The integrity of the tank lining is so diminished it is already leaking or within days or weeks of leaking. This is a valuable feature, to know that when you cannot maintain power to the electronic anode rod, you are about to experience a tank failure in the very near future. Time to schedule a change out!



Water can and will contain a variety of chemicals and minerals that can create adverse conditions when heated. The heating of the water will increase precipitation of scale. It causes the calcium to leave solution form and become a solid that sticks to itself and accumulates on heating surfaces.

High iron content is very common in Florida with well systems. Tannic acids will turn the water yellow to brown in color. Lime is naturally present in every water source to some degree. Bacteria can also be thriving in a particular water supply. The process of heating accelerates the various reactions. There is a wide range of targeted treatment and filtration products that can address these such as UV, Iron filters and the like.

It is important to remember that it is not the fault of the water heater, but a adverse reaction to the water…