Forecasters say 2012 Likely to Be a Better Year

 

A steady increase in Florida’s population, an uptick in housing starts and a gradually improving economy should make 2012 a better year for the state’s plumbing professionals. That’s the consensus of several economists who track Florida’s housing market.

“New job creation, rising rents and the inflow of international buyers are positive factors for the state’s housing market,” said Lawrence Yun, chief economist, National Association of Realtors, at the recent 2011 International Real Estate Congress in Coral Gables.  “Today, the smart money is chasing real estate.”

Florida’s population is likely to increase by about 130,000 people in 2012, according to John Silvia, chief economist, Wells Fargo. In a recent forecast, Silvia added that tourism and healthcare are leading the recovery, but other sectors will also be adding new jobs.

New housing starts will increase in 2012, says economist Sean Snaith, director of the University of Central Florida’s Institute for Economic Competitiveness in Orlando. He predicts about 55,000 new residential starts in the coming year. About three-fourths will be single-family homes and the rest will be multi-family construction.

“Nationally, U.S. housing starts are at the lowest level since the end of the second world war,” Yun said. “America is not building any homes, even though we are adding 3 million people a year to our total population. Building activity needs to triple in order to get back to a normal level.”

However, tight credit for builders and developers, as well as home buyers, remains a negative factor for the housing market, Yun added.  “The inventory of newly build homes is very low,” he said. “That means builders are selling whatever they can complete. The problem is that they can’t get construction loans in the current environment.”

While housing prices have stabilized in most Florida markets, they are still well below the boom-year peaks of 2004-2005. That’s because foreclosure sales continue to be a large part of the state’s real estate market. However, Yun said that lenders are bringing their REO (real estate owned) properties online gradually, rather than dumping them on the market at once. In addition, many lenders are recognizing that they lose less money by approving “short sales” (where the existing mortgage is larger than the home’s market value). Some are accelerating the sales process or even offering incentives for owners to move.

For Florida residential plumbing contractors, key opportunities include repairing foreclosed homes and other distressed properties, as well as additions and remodeling projects. One trend of note: some Florida parents are investing their excess cash by buying inexpensive homes and condos for their 20-something children. That allows these Millennials to have a place of their own that they can “fix up” and decorate themselves.

On the commercial side of the business, new construction is most likely to occur in the healthcare, retail and warehouse sectors. Little new office construction is likely as vacancy rates are now at 12 to 20 percent in the state’s major markets.

Yun notes that international trade will be one of the driving forces in the state’s economy in 2012. That could create new commercial opportunities in the state’s gateway cities like Miami, Fort Lauderdale, Jacksonville and Tampa Bay.  As Yun said, “In Florida’s commercial markets, the worst is probably over.”

 

 

 

KEY WATER HEATING CHARTS AND FORMULAS
by Rich Grimes 

It’s 2012 already and in this issue we will try to give you plenty of information and useful charts related to water heating. I don’t receive many requests so I am glad to accommodate on such a pertinent subject. The best part is that you won’t have to read too much from me as these charts and formulas speak for themselves! So here we go…

BTU

A British Thermal Unit (BTU) is a measurement of heat energy. One BTU is the amount of heat energy required to raise one pound of water by 1ºF. Water weighs 8.33 pounds per gallon so we can calculate that one gallon of water requires 8.33 BTU to raise the temperature 1ºF.

BTU CONTENT OF FUELS

ENERGY SOURCE                        BTU PER HOUR

COAL

1 Pound                                         =       10,000 – 15,000

1 Ton                                              =       25 Million (app.)

ELECTRICITY

1 KW                                              =       3,412

OIL

1 Gallon #1 Fuel                            =       136,000

1 Gallon #2 Fuel                            =       138,500

1 Gallon #3 Fuel                            =       141,000

1 Gallon #5 Fuel                            =       148,500

1 Gallon #6 Fuel                            =       152,000

GAS

1 Pound of Butane                         =       21,300

1 Gallon of Butane                         =       102,800

1 Cubic Ft. of Butane                     =       3,280

1 Cubic Ft. of Manufactured Gas    =       530

1 Cubic Ft. of Mixed                        =       850

1 Cubic Ft. of Natural                     =       1,075

1 Cubic Ft. of Propane                   =       2,570

1 Pound of Propane                       =       21,800

1 Gallon of Propane                       =       91,000

HORSEPOWER

1 Boiler Horsepower (BHP)            =       33,475 BTU

1 Boiler Horsepower (BHP)            =       34.5 Pounds of Steam @ 212ºF

1 Boiler Horsepower (BHP)            =       9.81 KW

COOLING

1 Ton of Cooling                             =       12,000

GAS INFORMATION

NATURAL             PROPANE

Specific Gravity                                                          =       0.62                    1.52

Flammability Limits (GAS/AIR Mixture)           =       4%-14%             2.4%-9.6%

Maximum Flame Propagation (GAS/AIR Mixture) =       10%                    5%

Ignition Temperature                                                =       1200ºF                950ºF

1 Pound of Gas (1 PSI)         = 28″ Water Column (w.c.)

1 Pound of Gas (1 PSI)         = 16 Ounces (oz.)

1 Therm = 100,000 BTU

 

ELECTRICAL INFORMATION

1 Kilowatt (kW)   =       3412 BTU Per Hour

1 Kilowatt (kW)   =       1000 Watts Per Hour

1 Kilowatt Hour (kWH) will evaporate 3.5 pounds of water from and at 212ºF

 

Amperage – Single Phase (1 Ø)      =       KW x 1000                   or      WATTAGE
                                                                         VOLTAGE                               VOLTAGE

 

Amperage – Three Phase (3 Ø)      =       KW x 1000                   or      WATTAGE
                                                                      VOLTAGE x 1.732                  VOLTAGE x 1.732

 

WATER HEATING FORMULAS

 

BTU Per Hour Requirement

BTU OUTPUT        =       GPM x Temperature Rise x 8.33 Lbs/Gallon x 60 Minutes

 

BTU INPUT           =       (GPM x Temperature Rise x 8.33 Lbs/Gallon x 60 Minutes)

% Efficiency

 

Heat Transfer Efficiency

% EFFICIENCY    =       (GPH x Temperature Rise x 8.33 Lbs/Gallon)
BTU/Hr INPUT

 

Heat-Up Time

Time in Hours      =       (GPH x Temperature Rise x 8.33 Lbs/Gallon)
                                               (BTU/Hr INPUT x % Efficiency)

 

Temperature Rise

Temp. Rise (∆T)   =           (BTU/Hr INPUT x % Efficiency)   

(GPM x 60 Minutes x 8.33 Lbs/Gallon)

 

GPH Recovery

Electric                =       (kW INPUT x 3412 BTU/kW x % Efficiency)

(Temperature Rise x 8.33 Lbs/Gallon)

 

Gas                     =                (BTU/Hr INPUT x % Efficiency)       

(Temperature Rise x 8.33 Lbs/Gallon)

 

MIXED WATER FORMULA

% of Hot Water Required      =       (Mixed Water ºF – Cold Water ºF)

(Hot Water ºF – Cold Water ºF)

 

WATER INFORMATION

1 Gallon     =       8.33 Pounds

1 Gallon     =       231 Cubic Inches

1 Cubic Ft   =       7.48 Gallons

1 Cubic Ft   =       62.428 Pounds (at 39.2ºF – maximum density)

1 Cubic Ft   =       59.83 Pounds (at 212ºF – boiling point)

1 Ft of Water Column (w.c.) = .4333 PSI

 

Water expands 4.34% when heated from 40ºF to 212ºF

Water expands 8% when frozen solid

 

OPEN VESSEL

BOILING POINT @ 0 PSI      ALTITUDE

212ºF                                    0 Feet (Sea Level)

210ºF                                    1000 Feet

208ºF                                    2000 Feet

207ºF                                    3000 Feet

205ºF                                    4000 Feet

203ºF                                    5000 Feet

201ºF                                    6000 Feet

199ºF                                    7000 Feet

 

CLOSED VESSEL BOILING POINT @ PSI @ Sea Level

BOILING POINT             GAUGE PRESSURE

212ºF                                    0 PSI

240ºF                                    10 PSI

259ºF                                    20 PSI

274ºF                                    30 PSI

287ºF                                    40 PSI

298ºF                                    50 PSI

316ºF                                    70 PSI

331ºF                                    90 PSI

ONLINE RESOURCES

There are an unlimited number of online tools and calculators for every mathematical formula. The internet is full of helpful resources to get the job done quicker. Here are a few links to some useful websites:

 

WEBSITE/PROGRAM                                         WEB ADDRESS

Amtrol Expansion Tank Sizing                                   http://amtrol.com/support/sizing.html

Engineering Toolbox Calculators                      http://www.engineeringtoolbox.com/

State Water Heater Sizing (Online)                          http://www.statewaterheatersizing.com/

AO Smith Water Heater Sizing (Online)            http://www.hotwatersizing.com/

Lochinvar Water Heater Sizing (Download)     http://www.lochinvar.com/sizingguide.aspx

 

Cylinder Calculator (Storage Tanks) / Other Math Calculators http://www.calculatorfreeonline.com/calculators/geometry-solids/cylinder.php

Electrical/Mechanical/Industrial/Civil/Chemical/Aeronautical Calculators http://www.ifigure.com/engineer/electric/electric.htm

B&G System Syzer (Piping/Pressure Drop Tool Download) http://completewatersystems.com/brand/bell-gossett/selection-sizing-tools/system-syzer/

B&G Selection and Sizing Tools (Pumps, Regulators, Steam and Condensate) http://completewatersystems.com/brand/bell-gossett/selection-sizing-tools/

Taco Pump Selection Wizard (Online Pump Selector)                                        http://www.taco-hvac.com/en/wizard_pumps.html

Lawler Mixing Valve Sizing (Online – account setup) http://www.lawlervalve.com/index.php?p=page&page_id=Sizing_Program

DSIRE Database of State/Federal Renewable Energy Rebates      http://www.dsireusa.org/

ASCO Valve Online Product Selector (Valves – solenoid, pilot, pneumatic, etc.) http://www.ascovalve.com/Applications/ProductSearch/ProductSearch.aspx?ascowiz=yes

 

SUMMARY

There is a lot of other information that we could add such as Steam. It is a viable heating source and there are several factors that must be considered such as operating pressure, steam trap and condensate line sizing and so on. We will have to do a separate article on Steam in a future issue.

The charts and information above are all essential to water heating. They are proven mathematical formulas of algebra and geometry. If you input the accurate information then the results will be correct. It is also good to use the online tools and calculators. They are true time savers.

Thanks and we’ll see you in the next article!

 

The Benefits of Building Information Modeling (BIM)
by  Mindy Delose, PE, LEED AP BD+C
Mechanical Engineer at RLF

Building Information Modeling (BIM) allows for the ability to exchange and coordinate a high level of information to aid in the design, construction, and post-construction of a building.  The A/E industry has seen a major shift from conventional 2D deliverables of construction plans and specifications to additional requirements, which include provisions for delivery of 3D BIM models.

Autodesk® Revit® MEP is a BIM software that has a lot to offer.  Sections, fixture counts, and pipe schedules can easily be generated within the building model for detailing or sizing equipment and determining pipe losses.  The best way to become familiar with the program is to begin using it on a regular basis.  The out of the box content is not usually sufficient for equipment families and often times needs to be created or modified to fit the application.  Manufacturer representatives and vendors in the MEP industry are increasingly offering Revit® content in addition to AutoCAD® files, available online as free downloads.  It is important to understand that the BIM model information is only as good as what is being input.  It is best to keep content as simple as possible as to not overload the model, but with enough information that other disciplines can properly coordinate and recognize specific parameters.  In this regard, all elements are not able to be modeled and it is important to distinguish between content which remains diagrammatic versus drawn to scale.  Once Revit® content is in place, it allows for a more thorough coordination between disciplines and the ability for clash detection between items in a room or above the ceiling.  In addition, a details library is good to have but does take time to develop, converting details from AutoCAD® layers into a Revit® format.  These details once converted can then be easily transferred from project to project.  One major difficulty in the transition from 2D to BIM is the amount of time it takes to implement.  It takes a lot of patience, training, and support from upper management and BIM managers to help facilitate those to become skilled at BIM.  Although it may seem similar to 2D software, there are a large amount of differences between the two.  As far as plumbing is concerned, riser diagrams are a challenge to transfer onto guidesheets in Revit® for larger buildings, which contain many complex plumbing systems.  Line breaks are not able to be viewed in a 3D view, which can lead to unclear schematic diagrams.  However, an added feature in Revit® MEP 2012 is the ability to now tag 3D views with annotations, something not offered in the past.  For smaller sized buildings it may become more suitable to incorporate 3D riser diagrams straight from the 3D Revit views, rather than linking in from AutoCAD®.

Autodesk® University (AU) [1] holds an annual conference which gathers input from architecture and engineering design firms who currently use BIM, whether it is professionals in the beginning stages or those already fully immersed.  Revit® MEP has come a long way from the earlier releases, but still has room for improvement, especially in the file performance and calculation areas.  Each year an updated version of Revit® MEP is released with features to continually progress the software and looks to add items that the majority of engineering designers feel the program is lacking.  The most current version

available, Revit® MEP 2012, has greatly improved functionality from previous versions.  The latest features can be found at What’s New on specific products at the following link: http://usa.autodesk.com/products/.   The conference is a wonderful experience for professionals to share knowledge and best method techniques to increase productivity and efficiency.  The combined feedback is also a way for Autodesk® to hear what is working well and what needs development.  The latest version, Revit® MEP 2013, is due out later this year around April.

Fortunately the amount of BIM users has been steadily increasing over the past few years so there is a much broader networker of experts to assist with solutions to most hurdles encountered along the way.  ASHRAE and ASPE occasionally participate in hosting BIM workshops for added support to familiarize designers on the subject.  In addition, there is access to an online forum[2] to find answers to questions.  Although there is approximately a two year learning curve to become fully functional and adaptive to the new BIM way of modeling, there are truly advantages that will pay off further down the road.  By assessing BIM’s short term setbacks versus the future advantages, embracing BIM will likely improve the overall business and increase the competitive advantage for the company.

Microorganisms: The effects of on-site water treatment
by Abigail Cantor, P.E.

This article is part of a series discussing the growth of microorganisms in plumbing systems.  As previously noted, many types of on-site water treatment equipment create conditions for microorganisms to grow and thrive by increasing the residence time of the water in the plumbing system with extra water storage volume, providing additional surface area for microorganisms to form biofilms on, and removing or using up any available disinfection to fight microorganisms.

The best practice in plumbing design is to provide on-site water treatment only when it is absolutely necessary to do so.  It is also important to select the appropriate treatment system, to determine a proper location for the equipment in the plumbing system, and to size the equipment so that volume and surface area are minimized.  Finally, automatic clean-in-place systems or manual cleaning protocols must be utilized to keep the equipment free of biofilms.

Determining Necessary Water Treatment

The first step in plumbing design is to determine specifically what contaminants, if any, are of concern in a building’s water source.  To do this, one must consider that there are numerous chemical compounds and types of microorganisms that can potentially contaminate drinking water.  Contaminants are identified and regulated in the United States with separate standards for municipal water systems, private water systems, and bottled water.  See Table 1.

If the building is connected to a public water system, the water has already been rigorously tested for the list of contaminants listed in Tables 2 and 3.  The results of those tests are public record, available at the regulatory agency that governs the state or territory where the building is located.  The results are also sent to each water utility customer annually in the Consumer Confidence Report.  There might be local issues to be concerned about, such as increasing concentrations of an industrial chemical in a public well.  In that case, the property owner should keep track of water utility plans to resolve the problem and attend water commission meetings, read the water utility website, or call the water quality manager.  If a building owner is not comfortable with the utility’s approach to removing the contaminant threat, then an on-site water treatment device should be used for removal.  It would be a rare and special case to need such a device.

It is possible for building plumbing systems to receive debris from municipal water distribution system piping.   Debris occurs in the distribution system when particles, like sand, settle out and when dissolved chemicals in the water, like manganese, iron, or aluminum, chemically precipitate out.  The possibility varies with the nature of the water and the water utility’s pipe cleaning and replacement program.  Debris can temporarily be entrained in the water during utility or road construction; it can happen seasonally due to water main flushing and other routine maintenance activities.  If a property owner experiences discolored water at an intolerable frequency, then on-site removal of the debris may be desired.

There is also the possibility that a building’s plumbing system leaches contaminants into the water.  Lead, copper, and iron are known to transfer from piping materials into water to varying degrees depending on characteristics of the individual water system.

If the property owner owns the water source, such as a private well, they must take the responsibilities of a water utility manager.  After complying with any state regulations on water quality for private water sources, the property owner must decide what other contaminants they might want to test for and, if significant, remove.  See Tables 2 and 3.  A common issue for private wells is high iron concentrations which can precipitate out and stain sinks and laundry.

For both private water sources and municipal water, the hardness of the water can be an issue.  Water hardness is mostly a measure of calcium and magnesium concentrations in the water.  Depending on other characteristics of the water, including temperature, the calcium and magnesium can precipitate out of the water as solid compounds.  The solids can cover heating surfaces in hot water heating systems, which in turn, will require more energy to heat the water; the buildup of solids will also reduce the life of the hot water heating tank.  For this reason, it is more economical to remove hardness from water where hardness is greater than about 120 mg/L as calcium carbonate (7 grains of hardness). Many people argue that hard water for cold domestic use should be softened; they state that hard water will clog pipes, create spots on glass shower doors, and react with soap so that it will not lather.  These are debatable arguments.  Even in locations with very high hardness (300 to 500 mg/L as calcium carbonate or 17.5 to 30 grains), cold un-softened water does not typically cause these severe problems.  Older residences in those locations only use softened water for the hot water system.  It is only recently, with modern plumbing practices, that cold water is also softened.

Determining Type of Water Treatment System

When specific contaminants have been identified in the water, then the proper contaminant removal technique can be selected.  The proper technique is the one that removes all contaminants of concern at the highest efficiency for the lowest financial and environmental costs.  Below are descriptions of common on-site treatment techniques.

Activated carbon filters

Activated carbon is carbon, typically from charcoal, that has been processed to make it very porous.  The more pores in the carbon, the higher the surface area.  The higher the surface area, the more specific contaminants can be pulled from the water to adhere to the carbon, a process called “adsorption”.

Different chemicals have different attractions to the carbon.  For example, heavier compounds have a greater attraction than lighter compounds.   This means carbon filters will not remove every type of contaminant.  In addition, the carbon can become saturated with contaminants and stop removing them.  Most importantly, just before the saturation point, the concentration of contaminants in the water flowing out of the filter begins increasing at a rapid rate.   Therefore, a carbon filter must be removed before the “breakpoint” of the least adsorptive contaminant or else the consumer will be drinking high levels of the contaminant that they intended to remove.  Filter manufacturers make assumptions as to what contaminants might typically be in water and set a common time when filters should be changed.   This may or may not be applicable in individual water systems.

Some carbon filters, such as certain ones that attach to sink faucets, are manufactured so that they combine treatment techniques within a small block of carbon.  Like other activated carbon filters, they have their limitations as to what contaminants can be treated and for how long.  In addition, the filters, themselves, can add contaminants to the water, based on compounds in the manufactured filter material.   There are research projects looking into this phenomenon.

Reverse osmosis and other membrane technologies

Reverse osmosis is a treatment technique that places a membrane barrier in the water.  The membrane is made of synthetic organic materials that do not have straight-through pores like a filter.  Instead, the pores are like a microscopic maze that can prevent many dissolved contaminants from passing through.  High pressure on the upstream side pushes the water, minus many of the contaminants, through the membrane.

There are other membrane technologies where the pores are straighter but very small.  Those technologies remove specific contaminants at lower pressures than reverse osmosis.

Membrane technologies prevent a percentage of the incoming water from going through the membrane, and instead, the water is sent down the drain to waste with the rejected contaminants.  The technique is not practical when it is too expensive to waste a percentage of the available water.  In addition, the synthetic organic membranes can dissolve in contact with some chemicals that might be in the water.  Chlorine used for disinfection is one of the chemicals and it is typically removed in a carbon filter upstream of the membrane.

Physical filters

Physical filters provide a physical barrier that can remove particles from water.  The filters can be made of sand or flossy material that will not allow particles of a certain size to pass through.

Ion exchange/water softeners

Ion exchange is a treatment process where one ion is taken out of the water and others are put into the water in its place.  An ion is an atom or molecule with either additional electrons or missing electrons; this gives the atom or molecule a negative or positive electric charge.   Water softeners are an example of an ion exchange process.  Here, calcium and magnesium, dissolved in the water as positively-charged ions, are “stuck to” negatively-charged ions.  When in contact with the ion exchange material, they are attracted and adhere to the material.  In exchange, the material releases two sodium ions for every calcium or magnesium ion; the sodium ions, then, form a union with the negatively-charged ions that were left behind in the water.  In the case of softening, the sodium concentration increases in the water.

At certain intervals, the ion exchange material must be cleaned to knock off the exchanged ions and replenish the original type of ions on the material.  In the case of water softeners, a solution of sodium chloride (brine) is used to flush out the ion exchange material.  This regeneration process creates a waste stream of chloride-laden water that is sent down the drain and out to the wastewater treatment plant.

Iron and manganese removal

Dissolved iron and manganese in the water eventually react with an oxidant like oxygen or chlorine in the water and precipitate out as a solid on pipe walls, sinks, and laundry.  To remove dissolved iron and manganese before it drops out elsewhere, an oxidant is pumped or bubbled into the water.  After a certain contact time, the iron and manganese are oxidized to a solid form and the particles are filtered out in a sand filter.

The filter must be backwashed periodically to clean the solids out and send them in a waste stream down the drain.

Sequestering

Sequestering is used to hold metals like iron and manganese in the water and prevent them from precipitating out as solids.  Traditionally, polyphosphate chemical products have been used in water systems to hold the metals in the water.  This is especially done when a small water utility or private property owner cannot afford a treatment process to remove iron and manganese.

It is now known that the use of polyphosphates carries negative side effects.  The polyphosphates not only can hold iron and manganese in the water but can also pull lead, copper, and iron from pipes and hold those metals in solution as well.  The consumer drinks any concentration of the metals being held in the water.  Polyphosphates also provide an essential nutrient, phosphorus, for the growth of microorganisms and in doing so, can aid in biofilm formation.  Finally, as the phosphorus from the polyphosphates eventually flows to waste, the wastewater treatment plants struggle with meeting stringent phosphorus discharge limits.

Disinfection

This series of articles on the growth of microorganisms and the formation of biofilms in piping systems has emphasized that disinfection of water is a main weapon against microorganisms.  With a clean piping system, it typically only takes a low dose of disinfection (0.3 to 0.5 mg/L free chlorine) to fight off intruding microorganisms and keep the piping system clean.

When on-site water treatment systems remove or use up disinfection in the incoming water, a dosing system should be added to replenish the disinfection in the water.  For owners of private water sources, continuous disinfection of the water before and after any treatment should be considered.

Some people complain about the taste of chlorine in their water.  If that is in issue, then drinking water can be left in a big pot open to the air or with cheesecloth covering it to allow the chlorine to transfer from the water into the air.  Alternatively, chlorine can be removed by a carbon filter at the drinking water faucet.  (Refer to the carbon filter discussion above.)

A more serious negative effect of disinfection is the possible formation of carcinogenic disinfection by-products.  This can occur when the water has high naturally-occurring organic carbon compounds that react with the chlorine.  If water is received from a municipal water system, disinfection by-products are tracked and minimized by regulation (Table 2); the property owner should re-chlorinate water within the concentration boundaries of the municipal utility.  For private water sources, the owner should become familiar with the disinfection by-product forming potential in the water and chlorinate accordingly.

Determining the Location of the Water Treatment System

Treatment systems located at the point in the plumbing where the water enters the building is called a point-of-entry water system.  Treatment systems located at the drinking water faucet are called point-of-use systems. The location of on-site water treatment in a building’s plumbing system is a critical design decision.

Point-of-entry systems treat the complete water flow to the building and are subsequently larger in size than point-of-use systems.  This creates a greater possibility of biofilm formation in the treatment equipment from increased surface area and retention of water.  It also increases the volume of water needed to clean and maintain the treatment system.  Many point-of-entry systems remove or use up incoming disinfection and so all of the piping downstream of the treatment system is not protected from the growth of microorganisms unless a disinfection dosing system is added.

Although smaller with little or no waste streams, point-of-use treatment systems must be installed for every drinking water faucet, while point-of-entry systems are installed at one location only.

Water treatment equipment for specific needs, such as water softeners for hot water, should be located as close to the specific need as possible.  Water softeners are typically located in a mechanical room adjacent to the water heating system.

Sizing Water Treatment Equipment

The goal of proper modern plumbing design should be to minimize volume of water retained and surface area of the treatment equipment.  The larger the size of the water treatment equipment, the more volume of water is retained on-site and the more surface area is available for biofilm formation.    As already discussed, one way to minimize volume is to eliminate treatment equipment unless absolutely necessary.  In addition, the volume of water to be treated should be carefully considered.  Divide the estimated total water use into: water for drinking/cooking, water for cleaning, and water for any significant purpose such as filling large bathtubs.  Design separate pipelines and treatment strategies for each purpose.

Cleaning Water Treatment Equipment

Various types of water treatment systems have cleaning cycles.  Sand filters must be backwashed to remove trapped solids.  Ion exchange material must be backwashed to remove solids and must be regenerated to replace ions.  Water treatment of this type has automatic clean-in-place cycles.  The cleaning water can be chlorinated to disinfect and fight developing biofilms routinely.  It is critical to work with the equipment manufacturer in setting up a cleaning water disinfection system; chlorine in too high a dose can destroy the treatment material.

Filters that require replacement of filter cartridges should be changed before or at the time recommended by the manufacturer to prevent breakthrough of contaminants and the development of biofilms.

Summary

This article continues the series warning against the growth of microorganisms and the formation of biofilms in plumbing systems.  On-site water treatment systems can contribute to the growth of microorganisms by increasing  the retention time of water, increasing the surface area where biofilms can form, and by removing or using up disinfection in the water.

The first step in plumbing system design is to determine which contaminants in the water are essential to remove on-site.  In many buildings that receive municipal water, additional water treatment is not necessary.  There is a greater need for on-site water treatment when the building is served by a private water source where the property owner must manage their own personal water utility.  There are also special needs for water treatment such as the need to soften hard water before it enters a hot water heating system.

After it is determined what contaminants must be removed, the best removal system must be selected.  Every treatment system has advantages and disadvantages and has specific removal efficiencies for each individual contaminant.   The sizing of the water treatment equipment and its location in the plumbing system are also critical design choices affecting the growth of microorganisms.

Finally, all water treatment equipment must be cleaned and disinfected or filter cartridges replaced routinely to clean out and prevent the formation of biofilms.

Maintaining a high water quality, including the elimination of microbiological growth, is a very delicate balancing act that should be given the highest priority when designing a plumbing system.