Water

• Certain existing fixtures, such as bathroom faucets, may not need to be replaced to meet requirements. They can instead be retrofitted with accessories (e.g., aerators) to reduce water flow to the requisite level. WaterSense-labeled accessories are available and recommended.
• WaterSense-certified toilets are available in several levels of efficiency and operation types. Toilet flush categories that qualify for WaterSense include high efficiency (1.28 gallons per flush or less) and ultra-high efficiency (1.1 gallons per flush or less). Different flush mechanisms include dual flush, gravity flush, and pressure-assisted flush.
• Factors to consider when making equipment selections include:
  • » The level of water-use reduction you are targeting
  • » Cost and availability
  • » The functionality of your existing pipe network
  • » The needs of the resident population
  • » Whether you intend to use nonpotable water for toilet flushing (see Criterion 4.6 Indoor Water Efficiency: Nonpotable Water Reuse)
• For projects serving primarily older adults, consider using single-flush toilets that meet the required flow rates rather than dual-flush toilets. Feedback from past Green Communities project teams suggests that these populations may be unfamiliar with the dual-flush technology, which may lead to difficulty in operating the toilets and could impact water performance.
• Dual-flush toilets have an average flow rate calculated and provided by the manufacturer. If you cannot locate this information, use a 2:1 ratio for low-volume flush to high-volume flush to determine the average flow rate. For example, with a dual-flush toilet that has a 0.8 low-volume flush and a 1.6 high-volume flush, the calculation to determine the average would be:

• Reduce total indoor water consumption by at least 30% compared to the baseline shown in Table 4.1 above. Points are awarded according to the percentage reduction against the baseline, as shown in Table 4.2.

• Ensure that any toilets, showerheads, and/or lavatory faucets newly installed in the certifying project are WaterSense certified. The Green Communities Water Calculator is available to calculate and compare your project’s indoor water consumption to the values in Table 4.1. When making your comparison, assume that the baseline project has the same types of fixtures as your certifying project. For instance, if your project does not include dishwashers, do not include dishwasher water consumption in your baseline project calculation. [2–8 points]

Meet the efficiency requirements for WaterSense-labeled homes via an EPA-approved certification method (www.epa.gov/watersense/homes-certification#approvedhcos). [8 points]Examples include:

• CHEERS WaterSense rating with a score of 70 or lower
• Water Efficiency Rating Score (WERS) with WaterSense baselines and a score of 66 or lower
• NGBS Certified Water Rating Index (WRI) with a score of 64 or lower
• HERSH2O rating with a score of 70 or lower

1. Lead service lines

2. Legionella water-management program

The program must include:

• Identification and mapping of water-system components
• Analysis of potential hazard points for Legionella growth
• Control measures (e.g., temperature management, disinfection)
• Ongoing monitoring and verification of control measures
• Documentation of corrective actions and annual reviews

3. Water testing and remediation

• Conduct comprehensive water testing early in the process. Even if not mandated, it is advisable to conduct testing for lead, nitrates, arsenic, and coliform bacteria during predevelopment due diligence or at the onset of rehabilitation planning. The early identification of contamination can facilitate cost-effective interventions and ensure the safety of residents.
• Install point-of-use filters. In instances where full replacement of lead service lines is not feasible — such as when facing jurisdictional limitations or partial ownership of service lines — it is recommended to install point-of-use water filters at kitchen taps that are certified to NSF/ANSI 53 along with a claim of lead reduction. In addition to that certification and lead-reduction claim, it is recommended that you also look for filters that are tested against NSF/ANSI Standard 42 for particulate reduction (Class I). Effectively reducing lead levels is particularly vital in buildings occupied by young children or people who are pregnant or nursing.
• Upgrade plumbing materials. During substantial rehabilitation or renovation projects, it is crucial to replace galvanized steel pipes and lead solder joints with corrosion-resistant materials, such as PEX or copper, certified to NSF/ANSI 61. This upgrade minimizes the potential for leaching of lead and other contaminants.
• Maintain optimal water-heater temperatures. It is essential to keep hot-water storage temperatures at or above 140°F (60°C), using mixing valves at points of use to mitigate the risk of scalding. This practice aligns with CDC guidelines to inhibit the growth of Legionella. The incorporation of thermostatic mixing valves will facilitate the safe delivery of water at recommended temperatures.
• Implement water-conservation measures carefully. When retrofitting low-flow fixtures, it is important to evaluate their impact on water age and stagnation within piping systems, particularly in multifamily buildings, since longer stagnation times can elevate the risk of bacterial growth. It is advisable to consider pipe-loop flushing protocols or smart recirculation systems as strategies to mitigate these risks.
• Train maintenance staff. Providing training on the optimal implementation of water-management systems is vital. This training should include monitoring temperatures, implementing flushing protocols, and recognizing conditions conducive to the growth of Legionella. Staff education plays a critical role in ensuring the ongoing effectiveness of the program. Communicate the critical need for this training and what it should include in materials completed for Criterion 8.1 Building Operations & Maintenance Manual and Plan.
• Communicate with residents. It is imperative to clearly communicate water-quality measures to residents through the Resident Manual and/or during move-in orientations. This communication should encompass guidelines on periodic fixture flushing, particularly for apartments that have been unoccupied for extended periods, as well as instructions for the cleaning of aerators. Incorporate this into the Resident Manual completed in Criterion 8.3 Resident Manual.

Prior to construction start (or permit close-out for early-start scopes), complete all of the following:

• Obtain at least 12 weeks of domestic water-meter data (15–60 min or monthly if interval is unavailable) and produce a preconstruction baseline identifying abnormal base load or night flow.
• Inspect 100% of common areas and a representative sample of dwelling units (at least 20% or 10 units, whichever is greater) for:
  • » Toilet leaks (dye/tab test or continuous-run check)
  • » Dripping faucets/showerheads and stuck mixing valves
  • » Visible leaks at hose bibbs, clothes washers, ice makers, and water-heater relief valves
• Perform at least one of the following. Choose based on building type:
  • » Pressure decay or districted shut-off testing on domestic mains/risers to isolate zones with losses OR
  • » Acoustic/ultrasonic survey of mains/risers/recirculation loops OR
  • » Thermal scan of domestic hot water recirculation to identify unintended cross-flows or failed check valves.
• For buildings with central domestic hot water (DHW) recirculation or cooling towers, verify:
  • » DHW return temperature and pump schedule AND
  • » Makeup-water meter function and recent trends for towers/boilers
• Submit a baseline chart or summary, an audit checklist, photos of representative issues, description of test method used and test results, and a corrective-action log with status (fixed, deferred, or in scope).

Install remote-readable meters that provide alerts and data logging at ≤ 5-minute intervals to separately monitor consumption for the list of water uses below. Ensure the alerts and readings from these devices are accessible to building management and that an operation and management protocol is in place to respond to meter alerts. Separately meter the end uses listed for either of these [2 points]:

• Each cold-water branch off the apartment line serving individual dwelling units
• Each cold-water riser and domestic hot water cold-water feed for all buildings in the project

And separately meter these end uses if they exist on the property, earning 1 point for each category, up to a total of 4 points. The categories:

• Common laundry facilities
• All toilets (both in dwelling units and in common areas)
• Boiler makeup water
• Outdoor water consumption
• Water consumption in any nonresidential spaces within buildings

• Integrate leak-detection and advanced-metering systems into the building management system to centralize monitoring, enable automated alerts, and support proactive maintenance planning.
• If a project has no vertical risers (e.g., garden-style multifamily with horizontal mains, townhomes, or single-family homes), leak-detection monitoring can be installed at horizontal mains/branches or via distributed dwelling-unit-level monitoring. Best practices include devices with data logging (≤ 5-minute intervals), programming to provide alerts to building staff, and development of an O&M response protocol.
  • » For horizontal mains/branch monitoring (no risers present), install continuous leak/flow monitoring and pressure or acoustic leak detection on the primary horizontal cold- and hot-water mains or recirculation loop(s) that together serve ≥70% of dwelling units by count. Appropriate devices include in-line flow meters, noninvasive ultrasonic meters, smart valves with flow/pressure sensing, or networked acoustic leak sensors.
  • » For distributed dwelling-unit-level monitoring (individual water heaters or all lateral plumbing), install a network of smart leak/flow sensors at unit entries, water heater cold inlets/hot outlets, or other strategic points covering ≥70% of units. Alternatively, install temperature + flow sensing on each DHW recirculation loop segment (if present), capturing return temperature and unexpected flow signatures indicative of leaks.
• For substantial rehabs in buildings with known histories of plumbing failures or outdated piping, prioritize installing leak-detection and -monitoring systems.
• Where possible, select systems that are compatible with ENERGY STAR Portfolio Manager or similar benchmarking platforms to support long-term tracking, reporting, and sustainability certifications.
• Encourage water conservation by providing residents with educational materials or digital dashboards that raise awareness of individual and building-level water use. Include in Criterion 8.3 Resident Manual.
• When feasible, coordinate leak-detection systems with water-quality monitoring (e.g., sensors to detect conditions favorable to Legionella growth) to enhance both water efficiency and occupant health protections.
• Engage plumbing contractors early in the process to optimize placement of meters and sensors, reducing installation costs and minimizing disruptions during construction or rehabilitation.
• Product innovations continue to evolve, with new monitoring and metering technologies available regularly. Explore product options during integrative design and discuss with the certification team before or during prebuild review.
• For substantial or moderate rehabs, after construction but within the first 30 to 60 days after stabilized occupancy, compile a 30-day consumption snapshot (interval if available) and a brief comparison to the preconstruction baseline, highlighting any anomalies and planned follow-ups (e.g., targeted submetering, fixture replacements, DHW recirculation balancing/controls, resident education). Keep a concise one-page trend summary for ongoing facility tracking.

Strategy A: 0.5-gallon storage limit

• Store no more than 0.5 gallons of water in any piping/manifold between the fixture and the hot-water source (i.e., the water heater or, if present, the recirculation line/riser pipe).
• To account for the additional water that must be removed from the system before hot water can be delivered, no more than 0.6 gallons of water shall be collected from the fixture before a 10°F rise in temperature is observed.
• For multifamily properties, this is applicable for plumbing systems in dwelling units and for central hot-water distribution systems for which the hot-water source is the hot loop.

Strategy B: 1.8-gallon storage limit

• Store no more than 1.8 gallons of water in any piping/manifold between the fixture and the hot-water source (i.e., the water heater or, if present, the recirculation line/riser pipe).
  • » For single-family homes, the storage volume is measured between the hot-water source and the farthest fixture.
  • » For multifamily properties, this storage requirement is applicable for plumbing systems in dwelling units and for central hot-water-distribution systems.
• Install water heater(s) with a Uniform Energy Factor (UEF) ≥ 0.87 for gas (generally tankless will meet this) or UEF ≥ 2.2 for electric.
• U se WaterSense-labeled fixtures for all dwelling-unit showerheads, bath faucets, and aerators.
• Multifamily properties must also ensure that recirculating central hot-water-distribution systems meet or exceed pipe insulation thickness criteria, as shown in Table 4.5.

• Effective and efficient distribution of hot water requires a whole-system approach and can be challenging to many builders. Considering the hot-water delivery system early in the design phase and then carefully following a plumbing design can help deliver superior homes and reduce installation costs.
• A hot-water distribution system with less stored water in its piping will waste less water and energy. Factors like the pipe diameter, the piping material, and the length of piping between the water heater and each fixture can all have a great cumulative impact on efficiency.
• Insulating hot-water pipes can improve the efficiency of a hot-water distribution system. Insulation reduces the rate of heat loss and can deliver water that is 2°F to 4°F hotter than uninsulated pipes can; insulation also maximizes consecutive-use efficiencies. Pipe sleeves made with polyethylene or neoprene foam with thicknesses of either ½ or ¾ inch are the most commonly used insulation. The inside diameter of the pipe sleeve should match the diameter of the pipe for a close fit. Secure insulation closely to the pipe every one or two feet with tape, wire, or cable ties. Insulation should be used along the entire length of hot-water pipes, including elbows and joints, but should be kept 6 inches away from the flue of gas water heaters. Insulation performs better with an R-value of 3 or greater.
• For single-family homes and individual dwelling units, consider central core plumbing and/or multiple stacked central core plumbing layouts, locating the water heater very close to hot-water fixtures.
• For single-family homes and multifamily dwelling units, try to minimize the area of the hot-water system within the footprint of the home. WE-Stand 2023 limits the area of the hot-water system to 60% of the total floor area.
• Plumbing layouts should have no dead legs. These would be particularly problematic in larger multifamily buildings because they can lead to stagnation and can significantly increase the age of water, elevating the risk of microbial growth.

• Use of nonpotable water indoors is subject to state and local regulations and requirements; in some jurisdictions, these systems may not be allowed. Check with local building code officials for requirements.
• Use the design water-use calculations from the Green Communities Water Calculator (see Criterion 4.1 Water-Conserving Fixtures) as the baseline to determine the percentage reduction of potable water use you may be able to achieve.
• Proper signage should be displayed in relevant areas to caution users that the water source is nonpotable.
• Packaged greywater systems are commercially available to recycle water within a residential unit. In a bathroom, shower, or sink, drainage can be treated and routed to the toilet. If laundry is in a common area in the building, the laundry wastewater could be used to flush toilets or urinals in common areas.
• Consult local codes and regulations to determine whether indoor use of nonpotable rainwater captured in rain barrels or cisterns is permitted at the location. If permitted, systems using rainwater for indoor nonpotable use should be designed by a professional certified by the American Rainwater Catchment Systems Association (ARCSA) or equivalent.
• Rainwater may also be an option to reduce potable use outdoors; see Criterion 3.6 Outdoor Water Use: Alternative Sources.

• In many cities, pressure typically brings water up to the fourth floor of taller buildings, with pumps used to deliver water to higher floors. If the power grid fails and backup generators are not connected to water pumps, or if generators also fail, residents should have access to a place in a common room to fill containers with potable water. This could be a centrally accessible corridor or utility closet. Specifics will vary by project.
• To ensure all residents can access potable water, develop a distribution plan that designates members of the building management team to facilitate transport of water to residential dwelling units throughout the property from the pressurized fixture locations (e.g., common spaces on lower floors) or the designated water-storage location.
• Consider pairing Criterion 5.6 Backup Power with Criterion 4.7 Access to Potable Water During Emergencies by designating pumps as a critical load and ensuring adequate emergency power to supply potable water to community rooms or other easily accessible spaces.
• Install redundant pumps with stored battery power to enable water to be distributed in taller buildings during a power outage.
• For properties that use rooftop tanks to maintain pressure, it may be possible to use these tanks as a source during emergencies, with proper controls and access.
• Harvested rainwater or pumped water can be stored on top of buildings, in utility space in buildings, or in separate water tanks. Any stored water intended for potable use, including harvested rainwater, must meet potable-water-storage requirements. Consult local building code officials to determine whether locally stored pumped water or rainwater is permissible as a source of potable water and, if so, what the requirements are.
• In rural or suburban areas that rely on on-site water (e.g., a domestic well) rather than municipal water, advanced modern hand pumps can provide a resilient water supply.