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Water Efficiency & Management

Home Water Score

Project completes a formal Home Water Score assessment as supplemental water-performance documentation.

Home Water Score logo

Description

The Home Water Score badge recognizes projects that complete a formal Home Water Score (HWS) assessment as supplemental water-performance documentation, even when the fixture-flow pathway is being used for tier compliance. The HWS is GreenHome Institute's calculator that integrates indoor fixtures, landscape, and rainwater catchment into a single 1–10 score, drawing on the "Residential End Uses of Water" study.

Earning the badge does not require a particular score threshold — it requires running the assessment, documenting the inputs, and submitting the score. Projects that perform well on the score often unlock alternative compliance pathways elsewhere in the standard (showerheads, aerators, toilets, and Platinum energy + water tier alternatives).

Equivalent assessments — WERS, HERS H₂O, Water Rating Index (WRI), or EPA WaterSense Certification — qualify as substitutes for the Home Water Score itself.

Required standard requirements

To earn this badge, the project must meet all of the following existing GreenStar requirements:

Additional badge criteria

Beyond the required standard requirements above, the project must also satisfy:

Assessment

  1. 01.

    Complete a Home Water Score using the GHI calculator, with all fixture inputs (toilets, bathroom aerators, kitchen aerators, showerheads, dishwasher, clothes washer) entered from measured or spec-sheet values.

  2. 02.

    Occupancy assumed as (bedrooms + 1), per HWS convention — actual or estimated occupancy is not used.

  3. 03.

    Missing dishwasher or clothes washer scored under HWS "worst-case" rules (assumed non-ENERGY STAR unit will be installed).

  4. 04.

    Outdoor water completed via the EPA WaterSense Outdoor Water Budget Tool, with selections per the manual's guidance (e.g. xeriscape selection for adaptive/native plantings; microspray for drought-tolerant mixes; rotor/spray for non-tolerant turf).

Greywater & rainwater (optional)

  1. 01.

    Greywater and rainwater catchment savings are not directly modeled by the HWS formula. Projects with these systems submit an alternative calculation for case-by-case credit.

  2. 02.

    Recirculation loops in faucets qualify for a 12% waste-reduction credit on the affected fixtures — request special consideration when submitting.

Leak handling

  1. 01.

    Leaks are scored as binary in the HWS model — all leaks must be fixed before submission (any leak fails the leak portion of the score).

  2. 02.

    Leak test: take the required pressure-test reading, leave water off for 30 minutes, verify no pressure drop and no meter movement.

  3. 03.

    Homes with installed leak-detection systems automatically qualify for the no-leaks status if the system reports no leaks at submission.

Documentation

  1. 01.

    Completed Home Water Score report (or WERS, HERS H₂O, WRI, EPA WaterSense equivalent).

  2. 02.

    Fixture spec sheets and/or flow-rate test measurements supporting each entered value.

  3. 03.

    EPA Outdoor Water Budget tool output PDF.

  4. 04.

    Photos and receipts for all water-using devices, plus the pressure-test reading and leak verification.

  5. 05.

    For projects using greywater or rainwater catchment for credit: separate alternative water-savings calculation with assumptions documented.

Verification by tier

Evidence the project team submits at each certification tier. Cumulative — higher tiers include everything below unless noted otherwise.

  1. Certified

    Self-attestation
    • 01.

      Completed Home Water Score report from the GHI calculator (or WERS / HERS H₂O / WRI / EPA WaterSense equivalent).

  2. Silver

    Documents + photos
    • 01.

      Fixture spec sheets or flow-rate test measurements supporting each entered value.

    • 02.

      EPA Outdoor Water Budget tool output PDF with landscape inputs documented.

    • 03.

      Photos and receipts for every water-using device entered into the calculator.

  3. Gold

    Third-party test
    • 01.

      Pressure test reading + 30-minute leak verification, witnessed by a third-party rater or inspector.

    • 02.

      Where leak detectors are claimed for the no-leaks qualifier: device cut sheet and screenshot showing no leaks at submission.

  4. Platinum

    Post-occupancy verification
    • 01.

      12-month metered water consumption within ±10% of the HWS-predicted annual gallons (occupancy-adjusted).

Water Efficiency & Management Required from Certified Zero Water Capable Home Water Score

Showerhead Flow Rate

Average measured flow rate of all showerheads in the home. Alternative pathway: meet a Home Water Score threshold.

Spec by tier

TierSpec
Certified≤ 2.2 GPM average — or Home Water Score of 2
Silver≤ 2.0 GPM average — or Home Water Score of 3
Gold≤ 1.5 GPM average — or Home Water Score of 5
Platinum≤ 1.25 GPM average — or Home Water Score of 6

Scope

All showerheads installed in the dwelling unit, including primary, guest, and accessory bathrooms. Hand-held wands count as part of the fixture they share a valve with. Bathtub spouts and tub-only fillers are excluded.

Requirements

Performance targets

  1. 01.

    Measure the flow rate (GPM) of every showerhead in the home, then calculate the average across all heads.

  2. 02.

    The average GPM must meet the tier threshold shown in the "Spec by tier" table above. Hand-held wands are measured separately and included in the average.

  3. 03.

    Alternative pathway: the project may submit a Home Water Score report meeting the tier threshold in lieu of per-fixture measurement.

Documentation

Evidence the inspector / Institute will need.

  1. 01.

    Photo of each showerhead's manufacturer rating sticker or packaging showing rated GPM (and WaterSense label if applicable).

  2. 02.

    OR a field flow-test record for each showerhead, including date, room location, measured flow rate, and inspector signature.

  3. 03.

    OR a completed Home Water Score report referencing the dwelling and showing the required score.

Guidance

Why flow rate matters

Showerheads are typically the second-largest indoor water draw after toilets, and they pull from the water heater — so cutting shower flow saves both water and the energy used to heat it. EPA WaterSense estimates a typical household saves ~2,700 gallons of water and 330 kWh of electricity per year by switching from a 2.5 GPM head to a 1.5 GPM WaterSense head.

Field flow-test procedure

When the manufacturer rating is missing or you want field verification:

  1. 01.

    Set up

    Hold a graduated 1-gallon flow bag (or a calibrated container) under the showerhead. Turn the shower on full hot and full cold so the mixing valve runs at the same total flow it would in normal use.

  2. 02.

    Capture

    Once steady-state flow is reached (3-5 seconds), start a timer and capture water for exactly 10 seconds.

  3. 03.

    Calculate

    Divide the captured volume (gallons) by 10, then multiply by 60 to get GPM. Example: 0.25 gal in 10 sec × 6 = 1.5 GPM.

  4. 04.

    Record

    Record the result on the flow-test form along with the room/fixture identifier.

Resources

Note

WaterSense ratings are measured at 80 psi static pressure. Actual field flow at lower house pressures (most homes run 40-60 psi) may be lower than the sticker value, which is fine — the spec accepts the manufacturer rating as the documented value.

Example — Averaging across fixtures

A 4-bathroom home has showerheads rated at 1.5, 1.5, 1.8, and 1.5 GPM. The average is 1.575 GPM — passes Silver (≤ 2.0) and Gold (≤ 1.5? No, 1.575 > 1.5). To clear Gold, the 1.8 GPM head would need to be swapped for one ≤ 1.0 GPM, or all four upgraded to 1.5 GPM caps.

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Water Efficiency & Management Required from Certified Zero Water Capable Home Water Score

Bathroom Aerator Flow Rate

Average measured flow rate of all bathroom faucet aerators.

Spec by tier

TierSpec
Certified≤ 2.0 GPM average — or Home Water Score of 2
Silver≤ 1.75 GPM average — or Home Water Score of 3
Gold≤ 1.0 GPM average — or Home Water Score of 5
Platinum≤ 0.5 GPM average — or Home Water Score of 6

Scope

Aerators on every bathroom lavatory (sink) faucet in the dwelling. Kitchen, utility, and laundry-sink aerators are excluded.

Requirements

Performance targets

  1. 01.

    Measure or read the rated flow rate (GPM) of every bathroom faucet aerator in the home.

  2. 02.

    Calculate the average GPM across all bathroom aerators; the average must meet the tier threshold in the "Spec by tier" table.

  3. 03.

    Alternative pathway: submit a Home Water Score report meeting the tier threshold in lieu of per-fixture measurement.

Documentation

Evidence the inspector / Institute will need.

  1. 01.

    Photo of each bathroom aerator showing the stamped GPM rating (typically printed on the underside or on the packaging).

  2. 02.

    OR field flow-test record (date, location, measured GPM, signature) for each aerator.

  3. 03.

    OR a Home Water Score report referencing the dwelling.

Guidance

How to read an aerator

Bathroom aerators are stamped with their flow rate in tiny letters on the underside, on the side ring, or on the original packaging. The most common ratings are 0.5, 1.0, 1.5, 2.0, and 2.2 GPM. WaterSense-labeled aerators max out at 1.5 GPM and produce noticeably softer spray.

Swapping a non-compliant aerator

Most aerators swap in under a minute with no tools:

  1. 01.

    Unscrew

    Unscrew the existing aerator by hand (counterclockwise as you look up at it). If it is stuck, wrap with a rag and use slip-joint pliers gently.

  2. 02.

    Match thread

    Bathroom aerators come in male (M22 or M24) and female (M22x1) thread. Bring the old one to the store to match.

  3. 03.

    Install

    Hand-tighten the replacement with the included washer. No tools or thread tape required.

  4. 04.

    Test

    Run full flow for 10 seconds and re-measure to confirm.

Resources

Note

For Platinum, the 0.5 GPM target is aggressive but workable in bathrooms (faucets are used mostly for short hand-washing bursts). Kitchen faucets generally cannot run that low and are not covered by this requirement.

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Water Efficiency & Management Required from Certified Zero Water Capable Home Water Score

Toilet Flush Volume

Average flush volume across all toilets in the home.

Spec by tier

TierSpec
Certified< 1.6 GPF average — or Home Water Score of 2
Silver< 1.3 GPF average — or Home Water Score of 3
Gold≤ 1.0 GPF average — or Home Water Score of 5
Platinum< 1.0 GPF average — or Home Water Score of 6

Scope

Every toilet installed in the dwelling unit, including dual-flush models. Bathtubs, urinals (residential only), and bidets are excluded.

Requirements

Performance targets

  1. 01.

    Identify the rated GPF (gallons per flush) for every toilet in the home. For dual-flush toilets, use the higher of the two flush volumes (full flush) for compliance calculations.

  2. 02.

    Calculate the average rated GPF; the average must meet the tier threshold in the "Spec by tier" table.

  3. 03.

    Alternative pathway: submit a Home Water Score report meeting the tier threshold.

  4. 04.

    New construction at Silver and above must install only toilets meeting the tier threshold — averaging in older fixtures is not permitted on new builds.

Documentation

Evidence the inspector / Institute will need.

  1. 01.

    Photo of each toilet's manufacturer rating (cast or printed on the bowl behind the seat or on the underside of the tank lid) showing GPF.

  2. 02.

    OR completed measurement record (bucket-and-stopwatch method) for each toilet.

  3. 03.

    OR Home Water Score report.

Guidance

How dual-flush counts

For a 1.6/1.1 GPF dual-flush toilet, GreenStar counts the 1.6 GPF full flush — not a weighted average. The rationale is that occupants do not always select the appropriate flush, so the standard assumes worst-case usage. Single-flush 1.28 GPF WaterSense toilets typically outperform dual-flush models on this basis.

Retrofit options

For existing toilets above the threshold: (a) replace the toilet with a WaterSense unit, (b) install an adjustable dual-flush conversion kit (some are accepted by GHI; verify with the inspector before relying on this), or (c) install a tank fill-cycle diverter / displacement bag to reduce flush volume — last-resort, only useful for marginal cases.

Resources

Example — Averaging a mixed home

A 3-toilet home has units rated 1.6, 1.28, and 1.28 GPF. The average is 1.387 GPF — passes Certified (<1.6) but fails Silver (<1.3). Swapping the 1.6 GPF unit for a 1.28 brings the average to 1.28 — passes Silver and Gold (≤1.0? No, 1.28 > 1.0).

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Water Efficiency & Management Required from Certified Zero Water Capable Home Water Score

Plumbing Leak & Pressure Test

Pressure test the plumbing system; no leaks permitted. Documented via the LEED-format Water Pressure and Leak Verification Report.

Scope

All cold- and hot-water supply piping inside the dwelling envelope, from the point of entry (meter or well pressure tank) through every fixture connection.

Requirements

  1. 01.

    Pressurize the supply system per local plumbing code (typically 60-100 psi static or 1.5× working pressure, whichever is higher).

  2. 02.

    Hold the test pressure for the code-required duration (commonly 15 minutes for the basic test) with all fixtures closed.

  3. 03.

    Pressure must hold with zero observable drop. Any pressure loss requires the leak to be located and repaired before retesting.

  4. 04.

    On new construction, the test must be performed before drywall is closed in over the supply lines.

Documentation

Evidence the inspector / Institute will need.

  1. 01.

    Completed LEED-format Water Pressure and Leak Verification Report (or equivalent) signed by the plumber or GreenHome Inspector.

  2. 02.

    Photo or scan of the pressure-test gauge at start and end of the hold period (if available).

Guidance

Why it matters

A single 1/16-inch supply-line leak behind drywall can waste 15+ gallons per day and cause thousands of dollars in moisture damage before being noticed. The pressure test is the single most cost-effective failure check in residential plumbing.

Field procedure

Most plumbers run this as part of rough-in. For existing-home retrofits:

  1. 01.

    Isolate

    Shut off all fixtures and close the main shutoff temporarily; open one fixture briefly to confirm system pressure has not fluctuated.

  2. 02.

    Gauge

    Attach a pressure gauge at the outdoor hose bib or a service tee. Note the static pressure.

  3. 03.

    Hold

    Re-pressurize and observe the gauge for the required hold period. A drop of even 1-2 psi indicates a leak.

  4. 04.

    Locate

    If pressure drops, isolate sections (hot vs. cold, upper vs. lower floors) by closing intermediate valves and re-running to narrow down the location.

Note

Pressure tests do not catch slow leaks at fittings under normal operating pressure that only show up under thermal cycling. Bath fan and water-leak inspections during the moisture assessment cover those.

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Water Efficiency & Management Required from Certified Home Water Score

Clothes Washer Leak Protection

Use steel-braided supply hoses, OR install a drain pan under the clothes washer.

Scope

Every clothes washer installation in the dwelling, including stacked or laundry-closet units.

Requirements

  1. 01.

    Install stainless-steel-braided supply hoses (both hot and cold) — OR install a drain pan with a plumbed drain under the washer.

  2. 02.

    Either solution is acceptable. Some inspectors prefer the pan even with braided hoses for second-floor laundry rooms.

Documentation

Evidence the inspector / Institute will need.

  1. 01.

    Photo of the installed supply hoses showing the braided stainless sheath at both hot and cold connections.

  2. 02.

    OR photo of the installed drain pan with the plumbed drain line and where it discharges (floor drain, standpipe, or exterior).

Guidance

Why this is so cheap and high-impact

Standard rubber washing-machine supply hoses are the #1 cause of indoor water damage claims to insurers in North America. A burst rubber hose can dump 5-10 gallons per minute behind the washer until the water main is shut off. Braided stainless hoses cost ~$15/pair and last 10-15 years. Drain pans cost ~$30 and provide a backup if the hose still fails.

Note

Connect a smart water sensor (e.g. Flo by Moen, Phyn, even a $20 standalone unit) inside the drain pan or behind the washer for early-warning alerts. Not required, but it pairs naturally with this requirement.

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Water Efficiency & Management Required from Platinum Zero Water Capable Resilience Home Water Score

Water Leak Detection & Real-Time Metering

Real-time water leak detection and metering system installed.

Scope

Whole-home plumbing — the system must monitor the entire supply line for unusual flow patterns indicative of a leak.

Requirements

  1. 01.

    Install a whole-home water monitoring + leak detection system at the main supply line (post-meter, pre-distribution).

  2. 02.

    System must provide real-time flow data accessible via mobile app or web interface.

  3. 03.

    System must detect anomalous flow (continuous flow exceeding a threshold, indicating a likely leak) and alert the occupant within 1 hour.

  4. 04.

    Automatic water shutoff capability is strongly recommended but not required (alert-only systems are acceptable).

Documentation

Evidence the inspector / Institute will need.

  1. 01.

    System specification sheet (Flo by Moen, Phyn Plus, Sense Save, etc.) showing real-time metering + alert capability.

  2. 02.

    Photo of the installed unit at the main supply line.

  3. 03.

    Screenshot of the occupant's mobile app showing live data from the unit.

Guidance

Auto-shutoff vs alert-only

Auto-shutoff systems (Flo, Phyn Plus) close the main water valve when a leak is detected — they prevent damage even if the occupant ignores the alert. Alert-only systems (Sense Save, Streamlabs) are cheaper but rely on the occupant acting promptly. For Platinum-level homes, auto-shutoff is the better fit even though the requirement is permissive.

Pair with point sensors

Whole-home meters detect supply-line leaks but miss drain-side issues (washer drain backup, toilet overflow). Add inexpensive Wi-Fi water sensors under sinks, behind toilets, near the water heater, and in the laundry pan. Most whole-home systems pair with these as a unified alerting system.

Note

Many insurance carriers (Travelers, Liberty Mutual, Nationwide) offer 3-15% homeowner premium discounts for installed leak detection. Have the homeowner submit the device certification to their carrier after installation.

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Water Efficiency & Management Required from Platinum Home Water Score

Advanced Hot Water Delivery Test

Hot-water delivery passes the advanced test: ≤ 0.6 gallons before delivery and +10°F temperature rise.

Scope

Hot-water distribution from the water heater (or recirculation manifold) to the farthest hot-water fixture in the home.

Requirements

Performance targets

  1. 01.

    At the farthest fixture from the water heater, less than 0.6 gallons must be drawn before hot water arrives (measured from cold start, fixture wide open).

  2. 02.

    Within the same draw, the temperature must rise at least 10°F above the incoming cold-water temperature.

  3. 03.

    Test at every "long-run" fixture (any fixture more than 20 ft of pipe from the water heater).

Documentation

Evidence the inspector / Institute will need.

  1. 01.

    Completed hot-water delivery test record listing each tested fixture with: distance from heater, gallons drawn before delivery, peak temperature reached, time elapsed.

  2. 02.

    Architectural plumbing layout showing hot-water distribution (trunk-and-branch, home-run manifold, or recirculation loop).

Guidance

Why this matters

In a typical home, 10-25% of all hot water drawn never reaches the fixture — it cools in the pipe between uses. A home that passes the 0.6 gal / +10°F test saves 5,000-15,000 gallons of water per year and the energy used to heat it, plus shortens the wait time at the tap (under 10 seconds typical for compliant homes).

Design strategies

Compliance comes from one or more of: (a) home-run manifold distribution with 3/8" PEX trunks, (b) trunk-and-branch with the heater centrally located, (c) on-demand or temperature-modulated recirculation pump at the farthest fixture, (d) point-of-use water heaters for distant fixtures. Insulating hot lines to R-3 helps marginally.

Resources

  • PMI Hot Water Delivery System Performance — research

    Industry research showing typical hot-water wait times across distribution types.

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