The Economics of Water Conservation

Savings Calculator

Enter your building's details to calculate potential savings from upgrading showerheads

Current Flow Rate (GPM) Typical standard showerhead: 2.5 GPM

New High-Efficiency Showerhead

Number of Showerheads

Cost per Showerhead ($) Including installation

Population Served

Number of People Served Total daily users of these showerheads

Usage Days Per Year 365 residential, ~260 commercial

Water Heating

Heater Efficiency (%)

Utility Costs

Water Cost ($/1,000 gal)

Electricity ($/kWh)

Natural Gas ($/therm)

Annual Water Saved

0 gal

0% reduction

Water Cost Savings

per year

Energy Cost Savings

0 kWh

Total Annual Savings

water + energy

Payback Period

0 yrs

break-even

Cumulative Cash Flow

Return on Investment

Water Savings Visualized

10-year savings as fraction of Olympic pool

Pool Filled

Gallons Saved

Olympic pool: 660,430 gallons

Environmental Impact

Equivalent cars off road for one day (annual)

Calculate to see results

Cars/Day

lbs CO2/Year

Avg car: 24.5 lbs CO2/day

Net Present Value (10-Year)

5% discount rate

Investment

PV of Savings

IRR

10-Year Net

Water Savings

Daily Usage (Current) Flow × Duration × People 0 gal/day

Daily Usage (New) New Flow × Duration × People 0 gal/day

Annual Water Savings Daily Savings × Days 0 gal

Annual Water Cost (Gal ÷ 1000) × Rate $0

Energy Savings

Energy/gal: 0.171 kWh

Temp rise: 70°F

Energy Saved Gal × 0.171 ÷ Eff 0 kWh

Energy Cost Energy × Rate $0

GHG Reduction

CO2/kWh: 0.92 lbs

Car CO2/day: 24.5 lbs

Annual CO2 Reduction Energy × Factor 0 lbs

Cars Off Road CO2 ÷ 24.5 0

Financial Analysis

Investment Cost × Fixtures $0

Total Annual Water + Energy $0

Payback Inv ÷ Savings 0 yrs

NPV Σ(S/(1+r)^n) - Inv $0

IRR NPV = 0 0%

ESCO Model vs. Independent Retrofit

Why this calculator uses a self-funded approach for water fixture upgrades

ESCO Model

Traditional Approach

Upfront Cost

None — ESCO finances the project

Savings Retained

20–30% during contract

Contract Length

7–20 years

Performance Risk

ESCO guarantees savings floor

Audit

ESCO-conducted (conflict of interest)

Equipment Ownership

ESCO owns until contract ends

Overhead

High — legal, M&V, admin fees

Min. Project Size

Typically $500K–$1M+

Audit → ESCO Finances → Install → Split Savings → 7–20 yr Contract

Independent Retrofit

This Model

Upfront Cost

Owner-funded (budget or short-term loan)

Savings Retained

100% from day one

Contract Length

None

Performance Risk

Owner bears risk (mitigated by measured data)

Audit

Independent — no conflict of interest

Equipment Ownership

Owner from day one

Overhead

Low — direct procurement only

Min. Project Size

Any size — scales down easily

Measure → Purchase → Install → Keep 100%

Water fixture retrofits have 1–3 year payback periods — too fast and too simple to justify ESCO overhead. The independent model lets owners capture all savings with no long-term obligations.

Model Assumptions & Parameters

▼

Shower Usage

Shower duration min

Showers/person/day

Energy Constants

Temp rise °F

kWh/gallon

Therms/gallon

Emission Factors

CO2/kWh lbs

CO2/therm lbs

Car CO2/day lbs

Financial

Discount rate %

Inflation rate %

Analysis period years

Olympic pool gal

Manage Showerhead Fixtures

Add custom showerheads with advertised and measured flow rates. Star one as baseline for comparison.

Fixture Name

Advertised Max (GPM)

Measured (GPM)

Price ($)

Fixture Name Advertised (GPM) Measured (GPM) Price ($) Baseline Actions

Flow Rate Comparison

Add fixtures to this table to compare flow rates and projected savings vs. baseline. Projection: 12 fixtures, 72 people, 365 days.

Fixture	Advertised (GPM)	Measured (GPM)	Δ vs Baseline (GPM)	Annual Gal Saved	Projected Cost Savings
Add fixtures to the table using the "Add to Table" button above.

Projections use: 12 fixtures × 72 people × 8 min showers × 1 shower/day × 365 days/year. Water cost from calculator settings. Δ is measured flow vs. baseline measured flow — negative means lower flow (saves water), shown in green. Higher flow than baseline shown in red.

Edit Table:

Shop Fixtures

Behind the Calculations

Full derivation of the NPV savings model — every variable, every equation, every step

This page shows the complete mathematical framework behind the calculator. Each input is assigned a symbol, and the full Net Present Value equation is derived step-by-step from first principles. Run a calculation on the Calculator tab first, then return here to see your values substituted into each equation.

Net Present Value — Full Equation

NPV = −C₀ + Σⁿ_t=1 [ S₁ × (1+g)^t−1 / (1+r)^t ]

Where annual savings grow at inflation rate g and are discounted at rate r over n years

Variable Glossary

Inputs — User-Defined

F_c Current flow rate —

F_n New flow rate —

d Shower duration —

s Showers/person/day —

P People served —

D Usage days/year —

q Num. fixtures —

c_f Cost/fixture —

c_w Water cost/1k gal —

c_e Energy cost —

k Energy/gallon —

η Heater efficiency —

r Discount rate —

g Inflation rate —

n Analysis period —

C₀ Initial investment —

Intermediates — Derived Values

W_c Current daily water use (gal/day) —

W_n New daily water use (gal/day) —

ΔW Annual water saved (gal/yr) —

S_w Annual water cost savings ($) —

ΔE Annual energy saved (kWh or therms) —

S_e Annual energy cost savings ($) —

S₁ Year 1 total savings (S_w + S_e) —

Run a calculation first to see live values.

Go to the Calculator tab, fill in your inputs, and press "Calculate Savings"

Daily Water Usage

W_c = F_c × d × s × P

—

W_n = F_n × d × s × P

—

W_c = current daily water usage (gal/day), W_n = new daily water usage

Annual Water Savings

ΔW = (W_c − W_n) × D

—

Result: — gal/year

Annual Water Cost Savings

S_w = (ΔW ÷ 1000) × c_w

—

Result: —

Annual Energy Cost Savings

ΔE = ΔW × k ÷ η

S_e = ΔE × c_e

—

Result: —

Total Savings & Initial Investment

S₁ = S_w + S_e

—

C₀ = c_f × q

—

Net Present Value (NPV)

NPV = −C₀ + Σⁿ_t=1 S₁(1+g)^t−1 / (1+r)^t

—

NPV = —

Building Operating Costs

Enter your current building financials to see how water savings affect Net Operating Income

Gross Annual Rental Income ($) Total annual rent collected

Other Annual Income ($) Parking, laundry, fees, etc.

Vacancy Rate (%) Typical: 3-8%

Operating Expenses

Monthly Water Bill ($) Current monthly water/sewer cost

Annual Property Tax ($)

Annual Insurance ($)

Annual Maintenance ($)

Annual Management Fees ($)

Other Annual Expenses ($)

Building Details

Number of Occupants Total daily building occupants

Number of Showerheads

Number of Toilets

Number of Faucets

Current NOI

Before water savings

Annual Water Savings

Run calculator first

Projected NOI

After water savings

NOI Breakdown

Gross Rental Income $0

+ Other Income $0

− Vacancy Loss −$0

= Effective Gross Income $0

− Water/Sewer (Annual) −$0

− Property Tax −$0

− Insurance −$0

− Maintenance −$0

− Management −$0

− Other Expenses −$0

= Net Operating Income (NOI) $0

Property Valuation

See how water savings increase your property's value through the income capitalization approach

Annual Net Operating Income ($) Enter manually or calculate on Operating Costs tab

Capitalization Rate (%) See typical ranges below

Annual Water/Energy Savings ($) Beta Auto-filled from Calculator tab results

Property Type Beta Used to suggest cap rate range

Typical Cap Rate Ranges by Property Type Beta

Cap rates vary by location, property class, and market conditions. These ranges are national averages — your local market may differ.

Multifamily (Class A) 4.5 – 5.5%

Multifamily (Class B/C) 5.0 – 6.5%

Industrial 5.0 – 6.5%

Retail 5.5 – 7.5%

Office (Class A) 5.5 – 7.0%

Office (Class B/C) 7.0 – 10.0%

Source: CBRE U.S. Cap Rate Survey (H1 2025), national averages. Beta — Ranges are inferred from market data and may not reflect your specific property or submarket.

Color Coding

NPV Savings Calculation — Variable Flow Map

How measured flow rates become Net Present Value

1 Inputs

Measured

F_ccurrent GPM F_nnew GPM

Known / Utility

Ppeople Ddays/yr c_w$/1k gal c_e$/kWh c_f$/fixture qfixtures

Assumptions

dmin/shower sshowers/day kkWh/gal ηefficiency rdiscount ginflation nyears

2 Daily Water Usage

Current W_c = F_c × d × s × P

New W_n = F_n × d × s × P

3 Annual Savings (Volume)

Water ΔW = (W_c − W_n) × D

Energy ΔE = ΔW × k ÷ η

4 Annual Cost Savings

Water $ S_w = (ΔW ÷ 1000) × c_w

Energy $ S_e = ΔE × c_e

Total S₁ = S_w + S_e

Invest C₀ = c_f × q

5 Net Present Value

Final Equation

NPV = −C₀ + Σⁿ_t=1 S₁ (1+g)^t−1 / (1+r)^t