Where is Outdoor Water Use the Highest?

Outdoor municipal water demand in the United States is heavily concentrated in a small group of large, warm, and often arid states, which also experience the largest seasonal spikes in landscape irrigation.

Using state‑level estimates of outdoor demand (Mgal/day), per‑capita outdoor demand (GPCD), and seasonal increases from winter to summer, a new report by Healthy Green Spaces Coalition identifies geographic water demand hotspots.

Key Takeaways

Outdoor demand from public water systems is highly concentrated, with the top 5 states accounting for about 46.6% of the nation’s roughly 11,774 Mgal/day in outdoor use.
In the highest-intensity states, outdoor use can reach 60–67% of total deliveries to households and small customers, as seen in Nevada (67%), New Mexico (65%), and Utah (63%).
Seasonal peaks are extreme in arid and semi-arid states, with Utah showing a 150 GPCD increase in modeled outdoor demand from winter (40 GPCD) to summer (190 GPCD).

Concentration of Outdoor Use

Total modeled outdoor demand from public water systems is approximately 11,774 Mgal/day nationwide. The top 5 states account for about 46.6% of this volume, and the top 10 states account for about 59.9%, indicating strong geographic concentration.

The 10 highest-share outdoor‑demand states are shown

Nevada – Outdoor share: 67%.
New Mexico – Outdoor share: 65%.
Utah – Outdoor share: 63%.
Wyoming – Outdoor share: 63%.
Idaho – Outdoor share: 61%.
Montana – Outdoor share: 61%.
Arizona – Outdoor share: 60%.
Colorado – Outdoor share: 59%.
California – Outdoor share: 57%.
Texas – Outdoor share: 55%.

Large, warm, and often arid states dominate outdoor use, reflecting both climate conditions and irrigation practices that shape how much of municipal supply is routed to yards, gardens, and other outdoor uses.

Intensity Hotspots

Per-person outdoor use, as gallons per capita per day (GPCD), highlights irrigation intensity independent of population size. This metric is useful for understanding how much outdoor use each served resident adds to system loads, regardless of overall state scale.

The highest-intensity states tend to be arid or semi-arid, where maintaining green landscapes requires substantial supplemental irrigation:

Nevada – 120 GPCD, 67% outdoor share
Utah – 120 GPCD, 63% outdoor share
New Mexico – 110 GPCD, 65% outdoor share
Wyoming – 100 GPCD, 63% outdoor share
Idaho – 100 GPCD, 61% outdoor share

Several large states such as Colorado (95 GPCD), Arizona (90 GPCD), Texas (85 GPCD), and Florida (85 GPCD) combine high per-capita outdoor use with sizable populations, amplifying system impacts.

Seasonal Spike Hotspots

Seasonal increase (winter to summer GPCD) serves as a proxy for summer peak stress on water systems. States with high seasonal spikes experience sharp demand increases during the irrigation season, which can drive capacity planning and operational challenges.

The largest spikes occur in Utah (150 GPCD increase, from 40 to 190), Nevada (135, 45 to 180), Idaho (130, 35 to 165), New Mexico (130, 45 to 175), and Colorado (125, 30 to 155). Other notable spike states include Wyoming (120), Montana (115), Texas (100), Arizona (100), and California (90).

Typology of States

Based on our data, we can classify states into 3 categories:

High-use, high-seasonality: 29 states.
Low-use, low-seasonality: 19 states.
High-use, low-seasonality: 1 state.

High‑use, high‑seasonality states represent the most important opportunities for utilities to reduce peak‑day loads through outdoor efficiency, smarter scheduling, and targeted customer programs. Low‑use, low‑seasonality states generally require less aggressive outdoor demand management, though they can still benefit from best practices in irrigation and landscaping.

In high-intensity, high-spike states, a mix of smarter technology and landscape choices can substantially cut outdoor water use while keeping yards functional. Smart irrigation controllers that adjust run times for weather and season, along with drip systems and high-efficiency sprinkler nozzles, reduce overwatering and losses from wind, runoff, and evaporation. Drought-tolerant turfgrasses and low-water plant palettes further lower the amount of irrigation needed to maintain healthy landscapes.

When utilities and households combine these measures, they can reduce both average outdoor use and the sharp summer peaks that drive capacity needs. In regions where outdoor use dominates summer demand, even modest efficiency gains can produce large reductions in peak-day loads and help defer costly system upgrades.

Data by State

Methodology

Data sources

U.S. Geological Survey (USGS). Water Use in the United States (2015) – Public Supply and Domestic Water Use tables (state-level domestic use in Mgal/day and GPCD; baseline for outdoor estimates).
U.S. Geological Survey (USGS). Water Use in the United States (2020) – domestic water-use estimates (used for the 2020 GPCD and outdoor share table).
U.S. Geological Survey (USGS). National Water Information System – Water Use Data.
U.S. Environmental Protection Agency (EPA). WaterSense statistics and program materials (used for outdoor-use shares, seasonal behavior, and irrigation-intensity framing).
National Environmental Education Foundation (NEEF). “Home Water Use in the United States” (2021) – national context for residential water use and outdoor share.
U.S. Geological Survey (USGS). “Per Capita Water Use” activity – supports per capita framing and GPCD interpretation.

Analysis

The analysis relies on a state‑level dataset of outdoor municipal water demand constructed from USGS public‑supply and domestic deliveries (indoor + outdoor) combined with population served to obtain total system GPCD. From this baseline, outdoor demand is estimated by applying climate‑ and landscape‑specific outdoor fractions informed by EPA WaterSense, NEEF, and related studies that compare winter and summer use.

This dataset is expressed as:

Total outdoor demand (million gallons per day, Mgal/day).
Outdoor use as a share of total system use (percent).
Per-person outdoor demand (gallons per capita per day, GPCD).
Seasonal increase in outdoor demand from winter to summer (GPCD).

Seasonal winter and summer outdoor values are derived by comparing average winter and summer system GPCD and assigning lower outdoor fractions in winter and higher outdoor fractions in summer. “Winter Outdoor Use” and “Summer Outdoor Use” thus represent modeled winter and summer outdoor GPCD, and the “Seasonal Increase” is the difference between summer and winter outdoor GPCD.

States were ranked by:

Total outdoor demand (Mgal/day) to identify volume hotspots.
Outdoor demand intensity (GPCD) to capture per‑capita irrigation loads.
Seasonal increase (winter to summer GPCD) as a proxy for peak‑season system stress.

Additionally, states were grouped into a typology based on use level and seasonality: high‑use/high‑seasonality, low‑use/low‑seasonality, and high‑use/low‑seasonality, reflecting different profiles of outdoor demand and peak‑day risk.

Context and Limitations

Most utilities already maintain detailed customer‑level data and make planning and policy decisions at local or regional scales, rather than relying solely on national USGS estimates. In many service areas, utilities can provide monthly or seasonal summaries on request, including information on dedicated irrigation meters, large landscapes, and non‑residential outdoor uses. Where such data are limited, analysts often infer outdoor demand by comparing average summer deliveries to winter baselines and attributing the difference to irrigation and other warm‑season outdoor uses.

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