Household water use: 6 EPA figures to compare at home

Key takeaways

• Match each figure's conditions to your home.
• Check your bill's units and billing period before comparing totals.
• Compare outdoor watering months with months without outdoor watering.
• Use your own yearly bills to assess water costs.

Figures from the U.S. Environmental Protection Agency (EPA) can help you read that total, but each one describes a particular group of homes or a particular situation. A figure that fits one household may not fit another, so the conditions attached to each number matter as much as the number itself.

This post covers 6 EPA figures on household water use. For each one, it gives the figure as EPA states it, the group or conditions it applies to, and what it cannot show about your own home. The first section covers outdoor use because it is the broadest question.

Treat these figures as reference points, not targets. Some are estimates, some describe what a home can reach under particular conditions, and some are averages. Knowing which kind of number you are reading is the first step in using it well. Each section starts with the answer to its question, so you can read the heading and stop once you have what you need. If you only have time for two sections, the outdoor split and the winter leak check give the broadest context for a monthly bill.

Bills may also be easy to misread on timing. A billing period may not line up with a calendar month, and the leak figure in this post is written monthly, so check the span your bill covers before you compare the two. For help reading charges, see how to read your water bill.

How much of household water goes outdoors?

Nearly 9 billion gallons, or 30 percent, of the estimated 29 billion gallons used daily by households in the US is devoted to outdoor water use, according to EPA's Start Saving page.

That figure is a national estimate. It combines US households into one total, so it describes the country as a group rather than any single home. Individual homes can sit above or below that split, depending on how much water they put outdoors and how the rest of the household uses water.

In this post, outdoor water use means water used outside the house, such as for a lawn or garden. The EPA figure covers that category for US households as a group, so it does not show how much a single yard uses.

Start with the simplest comparison. Pick a month in which you know there was no outdoor watering, and a month in which you did water outdoors, then compare the two totals. The difference is a rough indication of outdoor use, though it also reflects changes in how the household uses water indoors that season. A separate meter for outdoor watering, if your property has one, shows that use directly and makes the comparison unnecessary.

Whatever method you use, treat the national split as a question for your own numbers, not an answer to them. The gap between the national share and your own share is where useful questions begin, such as whether the seasonal pattern in your bills matches the pattern EPA describes for hot or dry conditions.

Can a winter water bill point to a serious leak?

For a family of four with no outdoor winter water use, a monthly total above 12,000 gallons can point to a serious leak. That figure appears on EPA's Home Maintenance page.

Two conditions define the figure, and both matter. The first is the home: it must have no outdoor water use in winter. The second is the household: it must be a family of four. The wording does not extend the figure to other household sizes, and it does not cover a home that waters outdoors in winter. For those homes, this particular figure does not apply.

Think of the figure as a threshold for a check, not a diagnosis. It flags a monthly winter total that EPA says likely indicates a serious leak. It does not identify where the leak is, how large it is, or whether something other than a leak is behind the total. It helps to think about what changed in the household around the time the total rose, such as a new appliance or a change in how many people live at home.

If a winter total falls below 12,000 gallons, or below 16 CCF (16 hundred cubic feet), this figure does not flag it. That only means this threshold has not been crossed.

How do I check a winter total against EPA's threshold?

Confirm that the home and household match the figure's conditions, read the winter monthly total, and compare that total with 12,000 gallons or with 16 CCF (16 hundred cubic feet).

Take the case the EPA figure describes. A family of four lives in a home with no outdoor water use in winter, and its total for one winter month is more than 12,000 gallons. The steps below follow that case. Working through them in order keeps you from skipping the condition check, which decides whether the figure applies at all. If the conditions do not match, stop there and choose another figure from this post.

If your bill shows earlier months, use only the months that fit the winter condition. A month that included outdoor watering belongs outside this check, even if its total looks high or low.

1. Confirm the conditions. The home has no outdoor water use in winter, and the household is a family of four. Both match EPA's wording, so the figure applies.
2. Read the monthly total. In this case, the total for the month is more than 12,000 gallons.
3. Match the unit. If the bill reads in CCF, compare it with 16 CCF (16 hundred cubic feet), instead of 12,000 gallons.
4. Compare. The total is above the figure, so EPA's figure says this family likely has a serious leak.

That result flags a possible leak, not a cause. Have a plumber or your water utility check for the source before you act on it. For a practical follow-up, read how to check a water meter for leaks.

Keep a record of the monthly totals for each winter in one place, so that a single high month can be compared with the months before it.

How high can a household's outdoor water use get?

EPA says that in hot summer months, or in dry climates, a household's outdoor water use can be as high as 70 percent.

Read 70 percent as an upper figure for those conditions. It is not a prediction that every hot summer or every dry climate produces that share.

This is a different kind of number from the national estimate in the first section. The national estimate describes households as a group; the seasonal figure describes what a single household can reach under particular weather, so it answers a different question.

If your summers are hot or your climate is dry, keep the seasonal figure in mind when you compare summer readings with winter readings. A single hot summer is a weak basis for judging a whole year, because the figure describes what outdoor use can reach under those conditions, not what every season brings.

The table puts all 6 figures side by side. The last column keeps each figure's condition attached to it, so the comparison stays tied to the scope each figure states.

A group estimate, a leak threshold, an appliance comparison, and an average cost each answer a different question, so they should not be read as interchangeable. Check the last column before you decide which figure applies to your home.

How much less water does an ENERGY STAR clothes washer use?

EPA says an ENERGY STAR certified clothes washer uses about 30 percent less water than standard models.

The comparison is between models. Your household's gallon savings depend on its use and the machine being replaced. The comparison base is standard models, not your current machine, so the figure does not describe the change you would see in your own home.

The advice is tied to replacement. When replacing your clothes washer, EPA advises selecting an ENERGY STAR certified model, so the figure is relevant when a replacement is being considered.

The washer is one appliance among several. The washer comparison should not be applied to the whole household's water use.

If you are weighing a new washer, you can also look at the size of the loads you usually run and how often you run the machine, since both can change the household total. Water use is one factor to weigh alongside others when choosing a machine, and the EPA figure does not measure the others.

When you look at a washer's details before buying, check first for the ENERGY STAR certification. If a listing gives a water figure, compare it only with figures for the same kind of machine, so that the comparison stays between like models. See also how to plan water saving home upgrades.

What does an average family spend on water each year?

EPA says the average family spends $1,300 yearly in water costs.

That figure is an average across families, so a single home's yearly cost may be higher or lower. An annual cost alone cannot tell you the price of a gallon.

Your own yearly cost depends on your provider's charges and on how much water your household uses. Use those charges and your own consumption to build a forecast for your home.

To compare, set a full year of your own water costs against $1,300. A full year is the fairer comparison, since a single month can differ from the rest of the year. A year also covers more billing periods than any single bill does.

The average also does not divide spending between indoor and outdoor use. To estimate your outdoor costs, start with your own outdoor use and provider's charges. Because the average is a dollar amount for families in general, it is a budgeting reference rather than an accounting of your own bills. A budget built on the average will be less precise than one built on your own bills.

How do the 6 figures differ in what they measure?

They measure different things: a daily volume for US households, a share of that volume, a monthly threshold, a seasonal share, a comparison between washer models, and a yearly cost in dollars.

Units matter because the figures cannot be compared directly. A daily gallon figure is not in the same unit as a monthly gallon figure, and neither is in dollars. Only the gallon figures measure volume, and the dollar figure measures cost.

Percent figures express a share, so they depend on the total they are a share of. For outdoor use, the base is total household water use; for the washer comparison, it is water used by standard models. Keep those bases separate when assessing your own home.

Converting between water volume and cost requires your provider's charges. A homeowner who mixes a monthly threshold with a yearly cost can reach the wrong conclusion about a bill. Keeping each figure in its own unit makes clear which question it answers.

Illustrative example: compare a winter bill

Suppose, illustratively, a family of four has no outdoor water use in winter and a monthly bill showing 30 CCF. Compare 30 CCF with 16 CCF. The total exceeds EPA's threshold, so it points to a likely serious leak. It does not locate the source; the next step is a check with a plumber or water utility.

Today, find a winter bill and mark its billing period, units and total before choosing a comparison below.

Which figure should I start with?

Start with the figure whose conditions match your home, because each one applies only under the conditions EPA states.

If your home has no outdoor water use in winter and the household is a family of four, begin with the winter threshold. If your summers are hot or your climate is dry, the seasonal outdoor figure is the one to read next. If you are replacing a clothes washer, the ENERGY STAR comparison applies to that choice. The cost figure gives a yearly reference point, but it measures dollars, not water use.

Some homes will match more than one condition. A home can fit both the winter threshold and the summer figure, for example, but each figure still answers only its own question, so read them separately.