Chlorinated water is everywhere in the U.S. It can be found in swimming pools, drinking water and disinfectants, and we think nothing of it. Overseas in Germany, however, they either do not use chlorine or they chlorinate to a lower percentage than we do here, depending on the region.

I recently had an opportunity to work on a new hospital project in Germany on behalf of HDR, in conjunction with the U.S. Army Corp of Engineers (USACE) and the Federal Republic of Germany (FRG). I was tasked with helping my German counterparts navigate the Unified Facilities Criteria (UFC), ASHRAE and NFPA 99 standards.

Through multiple meetings, we found a new drinking water ordinance — Trinkwasser Ordinance Section 12 TrinkwV 2001 with amendment, dated Dec. 19, 2017.

The new 2018 German Trinkwasser Ordinance does not allow the use of additional chlorination beyond 0.2 ppm, or even secondary chlorination or injection systems. Part of my assignment was to provide a chlorine risk assessment to determine Legionella risks by following the ordinance and then following ASHRAE 188 for secondary water treatment (i.e., copper silver, chlorination, chlorine dioxide, ozone, etc.).

The goal of the analysis was to demonstrate that the combined U.S. and German requirements result in an equivalency utilizing the ASHRAE 188 Legionella Risk Management approach. This is not a comprehensive risk assessment. It’s only a domestic water risk assessment related to the secondary chlorination treatment and methods used by plumbing designers to reduce the risk of pathogens such as Legionella.

The report evaluated requirements from the UFC 4-510-01 (May 2016, change 1), UFC 3-420-01 (2004, change 10), AER 200-1 (Army in Europe Guidance for Drinking Water Management Requirements), DIN standards, final governing standards (FGS), the December 2017 Trinkwasser Ordinance, the 2015 ASHRAE 188 requirements, NATO Status of Forces Agreement (SOFA) and the Installation Management Command (IMCOM).

After reviewing those codes and ordinances, we determined that we needed a decision from IMCOM. While we waited for the USACE to receive a ruling from IMCOM, I continued to read through all the documents to determine what codes we needed to follow. I then had to put what I knew about designing a domestic water system in the U.S. to the side and remain open-minded about how the German designers design a domestic water system to combat Legionella.

The following is a summary of each code, ordinance and government document we were to follow.

UFC 4-510-01 

Section 9-2.5.1 says scale, sediment and biofilm are contaminants that support Legionella bacteria colonization, as well as other waterborne pathogens. Functions that support these contaminants include water supply source, system operating temperatures and pipe material. Control technologies for scale and sediment deposits normally minimize the contribution of these factors to pathogen colonization. Biofilms, however, are more resistant to some treatments.

Section 9-2.5.3 covers the UFC-required secondary treatment.

UFC 3-420-01

Section 506.1 was added to provide design guidelines for sizing hot water systems. This section identifies the water storage temperatures to design around, which is 140 F. It also provides Table 506 for water service temperatures to follow.

Section 607.1.3, Legionella Pneumophila, also covers stored water temperatures as well as delivery temperatures. For health-care facilities including hospitals, the super-heating temperature is identified at 170 F to be flushed periodically through a distal site (faucet, showerhead, etc.).

AER 200-1

Section 3-4 explains that a “DOD water system must maintain a detectable disinfectant residual (typically free of available chlorine or chlorine dioxide) throughout the entire water distribution system, except where determined unnecessary by the appropriate DOD medical authority.

“For compliance with this requirement, equipment used to monitor residual chlorine must have a minimum detection capability of 0.02 milligram per liter. Water systems lacking disinfectant residual must request that the supplier add disinfectant to the treatment process, provide internal disinfection treatment or request a medical exception through IMCOM Europe.”

FGS will ensure baseline chlorination is provided at 0.2.

IMCOM

Relevant information provided by the U.S. Army Europe IMCOM claims that maintaining a residual disinfection level in accordance with the FGS is necessary. German law is secondary to the NATO Status of Forces agreement allowing U.S. forces to follow their own standards.

IMCOM claims the accommodation to maintain a residual in the water distribution system is guaranteed under Article 48 of the supplementary agreement to the NATO Status of Forces Agreement. It states that under Article 53, paragraph 1, the supplementary agreement allows a force or civilian component to “take all measures necessary for the satisfactory fulfillment of its defense responsibilities.”

German law shall apply except “as regards the organization, internal functioning and management of the force and its civilian component ... and other internal matters which have no foreseeable effect of the rights of third parties.”

DIN standards

The DIN standards require distal flushing based on temperature and flow rates. They also require a minimum temperature of 60 C (140 F) for stored water.

• The three-liter rule. The Drinking Water Ordinance (§14 Abs. 3) requires, under certain conditions, a regular check of drinking water for Legionella. The criteria are:

1. Supply of drinking water.
2. Supply of domestic water to showers or other facilitie for nebulizing the drinking water
3. Supply of a domestic water system to a central water heating system.

• Definition of drinking water plant. According to §3 TrinkwV ("Definitions"), paragraph 12, a large-scale water-heating system for a large facility is:

1. A storage-type domestic water heater or an instantaneous-type water heater, each with a capacity of more than 400 liters; or
2. A content of more than 3 liters in at least one pipeline between departure, the drinking water heater and distal \ site; not considered is the content of a circulating pipe.

If only one of the two points applies, it is a large domestic water system.

• Determining the water volume. Most of the previously defined criteria can be identified quickly. The more complicated determination of the volume of water in a pipeline can be determined by the following information:

1. For all distal sites with domestic hot water, or the corresponding volume of water between the outlet of the domestic water heater and considered respective distal sampling point, the test will usually only require the volume for the farthest point from the domestic water heater. Domestic hot water recirculation pipes are not used to determine the volume of water.
2. The volume of water in the supply line between the domestic hot water tank and the farthest distal point less than or equal to 3 liters. You can get away with assuming that the supply lines to the closer sampling points have volumes of less than or equal to 3 liters. The prerequisite for this, of course, is that they have the same (or a smaller) pipe diameter and are from the same material.

• Determining water volume in the pipe sections. Refer to the operation and maintenance documentation data for calculating the volumes you can use. If the documents are not available, then use the orientation table provided in the DIN 1988-200, which will help you determine if the volume of water in the line to be considered exceeds 3 liters.

The entire length of the domestic hot water piping must be determined, and from the domestic hot water tank to the take-off furthest away. Consider the nominal pipe diameter (DN) and the material used. Use the table provided in the DIN standard to see which ones use piping length to determine a volume of water (3 liters), making sure the given parameter (nominal diameter and type of material) is reached.

This document goes on to provide a diagram of a three-story building, which depicts the location of sampling ports, sampling valves, the water heater and storage tank. From this diagram, four points are provided to help determine when to apply the 3-liter rule (volume-based).

1. There are several so-called 3-liter rules in Germany (volume-based) included in DIN1988-200 and DVGW worksheet W 551. In the regulations, the volume for individual supply lines is cold-limited to a maximum of 3 liters (DIN 1988-200, 8.1, VDI 6023, 6.3.1). Single supply lines are warm, limited to a maximum of 3 liters (DVGW W 551).

Plancal Nova, our calculation software, is based on DIN 1988-300, the smallest possible dimensioning of the nominal pipe sizes.

2. In DIN 1988, Part 200, Section 9.7.2.2 is required as the minimum outlet temperature at 60° C at the DHW cylinder. The 1988-200 defines discharge times and temperatures. In general, and without considering the type of sampling point, it requires a maximum hot water temperature of 55 C and a maximum cold-water temperature of 25 C after a maximum of 30 seconds.

3. Different from the temperature specification for hot water at the extraction point of 60 C in DIN EN 806-2, a hot water temperature of 55 C is required for Germany (DIN 1988-200). This specification corresponds to the usual and proven operating conditions in Germany, according to DVGW Code of Practice W 551.

With the described planning principles taking into account the design rules for domestic hot water and circulation pipes in DIN 1988-300, this requirement can be met.

In DVGW W 551, the circulation return temperature is set to 55 C.

4. The 1988-200 defines discharge times and temperatures. In general, and without regarding the type of sampling point, it requires a maximum temperature of 25 C for the chilled water after a maximum of 30 seconds. The planned rinsing stations measure the chilled-water temperature and record the flow rate per unit of time.

The VDI/DVGW 6023, Hygiene in Drinking Water Installations, Requirements for Planning, Execution, Operation and Maintenance, demands a regular water exchange every 72 hours or with microbiological proof every seven days at most.

ASHRAE 188 Standard 2015

Section 4.3.2, regarding requirements for health-care facilities, notes that such facilities meeting all the following qualifications shall comply with either the requirements in Sections 4.2, 6 and 7 or the requirements in Normative Annex A, Health-Care Facilities.

The health-care facility is accredited by a regional, national or international accrediting agency, or by the authority having jurisdiction over the facility’s infection prevention and control (IC) activities.

The IC program must have an infection prevention specialist who is certified in infection prevention control by the Certification Board of Infection Control and Epidemiology or other regional, national or international certifying body; or the facility must have an epidemiologist with a minimum of a master’s degree or equivalent.

AHSRAE 188 analysis

We provided a table/matrix of key element hazard conditions, control points, monitoring, limits and corrective actions per ASHRAE 188 section 6. The analysis showed the drawings meet ASHRAE 188 4.3.2 Healthcare Facility Requirements and section 4.2, including sections 6 and 7, as outlined in the analysis. We also provided the requirements for UFC, UFGS and AER 200-1.

We believe that all qualifications in ASHRAE 188 section 4.1, 4.2 and 4.3.2 will be met. If the project meets all the qualifications, then it shall comply with sections 4.2, 6 and 7, or the requirements in Normative Annex A.

System Description, Resolution

The project is fed through an elevated storage tank, which is chlorinated to 0.2 ppm at the water storage tank. It is then fed to the water main loop around the complex, which feeds each building. The line serving each building will have dual backflow preventers and a future connection for a chlorination unit to be installed (temporarily) if required to mitigate a Legionella or pathogen outbreak in the domestic water system.

The storage shall have chlorine, pH, temperature and level monitoring sensors, which report to the building management system (BMS) located at the central utility plant, and recorded for the annual report.

Included at the entry of each building will be a water-quality monitoring system that will perform two tasks. First, it will monitor chlorine, pH (5.5-9.2) and temperature levels and send signals to the BMS, which will trigger an alarm to have a maintenance staff member evaluate the water storage tank levels and provide corrections if required. Second, it will monitor chlorine, pH and temperature levels and send data back to the BMS to monitor and record chlorine levels for the annual report.

The cold-water lines serving areas of low use and end-of-service runs will be automatically flushed periodically by a monitored temperature sensor and timer at least once every 24 hours if not automatically flushed by the temperature sensor.

Hot water will be generated using instantaneous heat exchangers generating 140 F water. Hot water will be circulated (looped) at that temperature, which exceeds the UFC 4-510-01 section 9-2.6.2 requirement. This requires 122 F maximum temp and a return of 115 F at a maximum loss of 6 degrees. Hot water will be routed to within 10 feet of a faucet, which exceeds UFC 4-510-01 section 9-2.5.3.3 that requires a maximum of 20 feet. The faucets have thermostatic mixing valves, which will reduce hot water down to a 120 F delivery temperature.

The FGS shall be followed regarding providing secondary chlorination, which is permitted based on the NATO SOFA, Article 48 and 53, paragraph 1. The project will make attempts to meet German requirements; however, the USACE will retain the ability to raise chlorine levels from 0.2 ppm up to 0.4 ppm to control Legionella and other bacteria in the water supply.

When involved in an international health care collaborative approach, it is best to set aside what you know and open your mind to how other parts of the world treat their drinking water. Take what you have learned and evaluate it to see if the processes can be applied elsewhere.

From this experience, I came away with a better understanding of how others around the globe design to alleviate the formation of Legionella. I intend to use what I have learned to better my designs going forward.