How Much Water Does a California Household Use?

Most Americans use about 82 gallons of water a day at home, and California’s indoor water standard is much lower: 47 gallons per person per day. This guide shows where a typical household’s water goes, what the state rules actually say, how to read your water bill and how to work out your own number in a few minutes.

Quick answer: The average American uses about 82 gallons of water a day at home, according to EPA WaterSense. California’s indoor water-use standard is 47 gallons per person per day since January 1, 2025, and it drops to 42 gallons in 2030. Outdoor watering often adds as much again, or more, in summer.

Key numbers at a glance

• 82 gallons: average water use per person per day at home in the U.S. (EPA WaterSense)
• More than 300 gallons: average American family’s daily use at home, with about 70 percent of it indoors (EPA WaterSense)
• 47 gallons per person per day: California’s indoor residential standard from 2025 through 2029, falling to 42 on January 1, 2030 (California Water Code 10609.4)
• 58.6 gallons: average indoor use per person per day in the national Residential End Uses of Water study (Water Research Foundation, REU2016)
• Up to 60 percent: share of household water that can go outdoors in dry regions, compared with about 30 percent nationally (EPA WaterSense)
• More than 9,300 gallons: water an average household’s leaks can waste each year (EPA WaterSense Fix a Leak Week)
• 748 gallons: the amount in one billing unit (CCF or HCF) on most water bills (EPA WaterSense)

Want your own estimate right now? Our free Household Water Simulator adds up your use fixture by fixture and compares it with California’s standard.

How much water does the average household use?

Water use is usually measured in gpcd, which means gallons per capita (per person) per day. It lets you compare a single-person apartment with a family of five.

Across the U.S., EPA WaterSense says each person uses about 82 gallons a day at home, and the average family uses more than 300 gallons a day (EPA). Those totals include both indoor use (toilets, showers, sinks, laundry) and outdoor use (lawns, gardens, pools, car washing).

Indoor use alone is lower. The Water Research Foundation’s Residential End Uses of Water study measured more than 23,000 single-family homes and found indoor use averaged 138 gallons per household per day, or 58.6 gallons per person (REU2016). That was 15 percent less per person than in the first version of the study in 1999, mostly because of more efficient toilets and clothes washers.

California’s indoor water standard (SB 1157)

California sets an indoor residential standard in state law. Senate Bill 1157, passed in 2022, lowered it in steps (California Water Code 10609.4):

• 55 gallons per person per day until January 1, 2025
• 47 gallons per person per day from January 1, 2025, through December 31, 2029
• 42 gallons per person per day starting January 1, 2030

One important detail: this standard is not a limit on your house. It is used to set water-use targets for water suppliers. Under the state’s Making Conservation a California Way of Life regulation, which took effect January 1, 2025, urban retail water suppliers are held to these water-use objectives, not individual households or businesses (State Water Resources Control Board). Still, 47 gpcd is a useful goal to measure your own home against.

Where the water goes inside your home

Here is how indoor use broke down per person per day in the REU2016 study (Water Research Foundation):

• Toilets: about 14.2 gallons. The average flush used 2.6 gallons, and people flushed about 5 times a day.
• Showers: about 11.1 gallons. The average shower lasted 7.8 minutes.
• Faucets: about 11.1 gallons, for drinking, cooking, cleaning and handwashing.
• Clothes washers: about 9.6 gallons. The average load used 31 gallons.
• Leaks: about 7.9 gallons, and some homes leaked far more.
• Baths, dishwashers and other uses: the small remainder.

EPA puts toilets at nearly 30 percent of an average home’s indoor use, making them the single biggest indoor user (EPA WaterSense). Older toilets can use as much as 6 gallons per flush, while WaterSense labeled models use 1.28 gallons or less.

Showers are next. A standard showerhead flows at 2.5 gallons per minute, and a WaterSense labeled one uses no more than 2.0 (EPA WaterSense). EPA says the average family could save about 2,700 gallons a year by switching.

Leaks are the sneaky one. EPA estimates household leaks can waste more than 9,300 gallons a year per home, and 9 percent of homes have leaks that waste 50 gallons or more per day (EPA). A running toilet flapper is a common cause.

Why outdoor watering dominates in summer

In much of California, outdoor use is the biggest piece of the bill from late spring through fall. Nationally, outdoor watering is about 30 percent of household use, but EPA says it can reach 60 percent in arid regions (EPA WaterSense). The Public Policy Institute of California reports that outdoor use accounts for nearly half of all urban water use in the state (PPIC).

Much of that water never reaches plant roots. EPA estimates that as much as 50 percent of outdoor water is lost to wind, evaporation and runoff from inefficient watering. That is why California’s Model Water Efficient Landscape Ordinance sets water budgets for new and renovated landscapes (CA Department of Water Resources), and why lawns are often the first thing cities target in a drought.

How to read your water bill

Many water bills do not show gallons. They show CCF or HCF, which both mean one hundred cubic feet. One CCF equals 748 gallons (EPA WaterSense).

When you look at your bill, find:

• Billing period: the start and end dates. Many utilities bill every month; some bill every two months.
• Usage: the number of CCF or HCF used in that period.
• Usage history: a chart of past months. A summer spike usually means outdoor watering. A sudden jump with no change in habits can mean a leak.
• Tiers or rates: some cities charge more per unit as you use more.

How to calculate your own gallons per person per day

You only need one water bill and a calculator.

1. Find your usage in CCF or HCF for one billing period.
2. Multiply by 748 to get gallons.
3. Count the days in the billing period.
4. Divide gallons by days to get gallons per day for your home.
5. Divide by the number of people who live there. That is your gpcd.
6. For an indoor-only estimate, repeat with a winter bill, when you water the yard least.

Example: a household of three uses 12 HCF in a 60-day billing period. 12 × 748 = 8,976 gallons. 8,976 ÷ 60 = about 150 gallons per day. 150 ÷ 3 = about 50 gallons per person per day. If that was a winter bill, this home is close to California’s 47 gpcd standard.

If you live in an apartment where water is not billed separately, use the simulator instead. It estimates use from your habits and fixtures.

Top ways to cut your household’s water use

• Find and fix leaks. Check the toilet by putting a few drops of food coloring in the tank; if color shows up in the bowl after several minutes without flushing, the flapper leaks. A smart leak detector can warn you about hidden ones.
• Upgrade or adjust old toilets. A WaterSense toilet or a dual-flush conversion cuts the biggest indoor use.
• Shorten showers and use an efficient showerhead. A shower timer makes a shorter-shower habit easy.
• Add faucet aerators. They are cheap and take minutes to install.
• Run full loads in the clothes washer and dishwasher.
• Water outdoors early in the morning and set your irrigation timer by season, not once a year.
• Replace thirsty lawn with native plants. Drought-tolerant plants often need much less watering once established.

Use the Household Water Simulator

The Household Water Simulator is a free tool from the Accessible Sustainability Alliance. It runs in your browser with no sign-up. Here is how to use it:

1. Pick your region. Santa Monica, California is the default. The region picker updates local water and energy assumptions.
2. Enter your household size.
3. Set your fixtures and habits, such as shower length, showerhead flow rate, toilet type and laundry loads per week.
4. Add outdoor watering, a pool or leaks if your home has them.
5. Read your gpcd. The simulator compares it with California’s 47 gpcd indoor standard and shows which fixture uses the most.
6. Run the drought stress test. It shows how your home would do if your water supplier ordered mandatory cutbacks, and which changes would get you there.
7. Check the hidden energy. Pumping, treating and heating water uses electricity and gas, so the simulator also shows the energy and carbon tied to your water use.

Teachers can have students compare a winter bill result with the simulator’s estimate. The difference is a good starting point for a class discussion about outdoor use and leaks.

Frequently asked questions

How much water does one person use per day in California?

California’s indoor standard is 47 gallons per person per day from 2025 through 2029, dropping to 42 in 2030. Actual use varies by city and season, and outdoor watering can push total use much higher in summer. Nationally, EPA says the average person uses about 82 gallons a day at home, indoors and outdoors combined.

Will I be fined if my household uses more than 47 gallons per day?

Not under the state standard itself. California applies the standard to water suppliers, not to individual households. Your local water supplier can still set its own rates, tiers or drought rules, so check your city’s water page.

How many gallons is one unit on my water bill?

Most bills measure water in CCF or HCF, which both mean one hundred cubic feet. One unit equals 748 gallons. Multiply your units by 748 to get gallons.

What uses the most water in a house?

Indoors, toilets are usually the biggest user, followed by showers, faucets and clothes washers. In California, outdoor watering often uses more than all indoor uses combined during summer.

What is a good gallons per person per day number?

Under 47 gallons per person per day indoors meets California’s current standard. The Water Research Foundation found that homes with efficient fixtures throughout could get below 40.

See your household’s water use

Ready to find your own number? Open the free Household Water Simulator, enter your household and fixtures, then run the drought stress test to see which changes save the most water, energy and money.

Related guides

• How to Install a Faucet Aerator to Cut Water Use
• How to Set a Sprinkler Timer Once and Never Touch It Again
• How to Reuse Greywater for Toilet Flushing

Sources

• U.S. EPA WaterSense, Statistics and Facts
• U.S. EPA WaterSense, How We Use Water
• U.S. EPA WaterSense, Understanding Your Water Bill
• U.S. EPA WaterSense, Fix a Leak Week
• U.S. EPA WaterSense, Residential Toilets
• U.S. EPA WaterSense, Showerheads
• Water Research Foundation, Residential End Uses of Water, Version 2: Executive Report (2016)
• California Water Code, Section 10609.4 (indoor residential water use standard, SB 1157)
• California State Water Resources Control Board, Making Conservation a California Way of Life
• Public Policy Institute of California, Water Use in California
• California Department of Water Resources, Model Water Efficient Landscape Ordinance

Written and reviewed by the Accessible Sustainability Alliance editorial team. Last updated October 5, 2026.