How this calculator works
The calculator adds three lines you control:
shower gal/day = people × shower minutes × gpm
toilet gal/day = people × flushes × gpf
day = shower + toilet + other
year = day × 365Defaults are WaterSense-shaped and overwritable: 2.0 gpm (labeled showerhead maximum), 5 flushes (their calculator's 5.05 planning figure, rounded), 1.6 gpf (federal toilet standard, not the 1.28 WaterSense toilet). Other starts at 0 so laundry and a leak are visible holes rather than invented lumps.
If people is 0, there is no household to price. On this engine, a 0 in gpm, flushes, or gpf falls back to the default, so do not type 0 to mean "none." Set shower minutes to 0 to drop the shower line.
What each input means
| Input | What it is actually asking |
|---|---|
| People | How many people are actually drawing water on a typical day, not the number of bedrooms. |
| Shower minutes | Minutes under the head per person per day. Two short showers and one long one should be averaged, or run twice. |
| gpm | Shower flow. 2.0 is WaterSense labeled maximum. A 2.5 gpm older head is a different line. Timed bucket beats the stamp if you have one. |
| Flushes | Flushes per person per day. Planning default 5. Overwrite. Do not type 0; the engine will restore 5. |
| gpf | Gallons per flush. 1.6 federal, 1.28 WaterSense, 3.5 or 5 for older tanks. The mark inside the tank is the number to type. |
| Other | Everything else you want in the total: laundry, dishwasher, cooking, a measured leak. 0 means untyped, not "we do not do laundry." |
Worked examples
Including one where the naive answer misleads, which is the example most calculators leave out.
Four people, WaterSense-shaped shower, federal toilets
People 4, shower 8 minutes, 2.0 gpm, 5 flushes, 1.6 gpf, other 0. Shower 64 gal/day. Toilet 32 gal/day. Total 96 gal/day, about 35,040 gal/year. That is the default arithmetic on this form. Replace 2.0 and 1.6 with the stamps in the house and the minutes with how you actually shower.
The same house with WaterSense toilets and a known leak
Keep the showers. Set gpf to 1.28. Toilet drops to about 26 gal/day. Add 8.2 to other for the WaterSense drip from the leak tool. Daily total is then shower + toilet + drip, and the leak is visible instead of being blamed on the shower. That is the honest way to combine the two pages.
The one where a national "80 gallons a person" misleads
A roundup that says the average American uses 80 to 100 gallons a day, compared with 24 gallons of shower-plus-toilet on this form for one person, as if the house were unaccountably efficient. The gap is laundry, outdoor, leaks, and baths this sketch never claimed to include. Treating 96 gal/day for four people as a water bill, or as proof a tankless heater will pay back, is the other failure. Daily gallons are not GPM at a temperature rise, and they are not first-hour rating. Use the tank-vs-tankless and sizing tools for those, and the bill for the tariff.
What changes the result
Minutes and gpm move the shower line together. Cutting an 8-minute shower to 6 at 2.0 gpm saves as much as switching 2.0 to 1.5 at 8 minutes, for a given person. Neither change sizes a heater.
Flush count and gpf move the toilet line. A 3.5 gpf tank at 5 flushes is more than double 1.28. A running toilet is not gpf. It is a leak, and it belongs on the leak tool or in other once you have measured it.
People scale both fixture lines. Other does not, unless you typed it as a per-house lump. That is why laundry sits in other rather than being invented as a third default.
Local considerations
Fixture flow rates in a new installation are a local adopted-code question. WaterSense 2.0 gpm and the federal 1.6 gpf are national product rules, not a guarantee that your city has not gone tighter. If the head or the toilet is already in the wall, type the stamp, not the code.
Outdoor watering, climate, and a swimming pool are local and they are not on this form as a ZIP. Put irrigation in other only if you mean to mix it with indoor habits, and do not treat a July other line as a January bill.
The tariff is local. This page does not price gallons. The leak-cost tool does, from a rate you type off the bill.
When not to use this
Do not use this as a water bill, a meter reading, or a conservation rebate application. It cannot see irrigation, a leak you have not typed, or a person who showers at the gym.
Do not use it to size a tank or a tankless unit. Those are the sizing and payback tools.
Do not type 0 in gpm, flushes, or gpf to mean none. The engine restores the defaults. Set minutes to 0 instead.
HyrePlumber does not sell fixtures, read meters, or perform plumbing work. Matching is still being built.
Related on this site
- Water heaters on the homepage Sizing is recovery and demand, not this daily total.
- Preventable failures Supply hoses and pressure. Gallons here are habits, not those failures.
- What drives a plumbing bill A water bill is a tariff plus volume. This page is volume of habit only.
- Find a plumber An enquiry, not a fixture sale.
Questions this calculator answers
- How much water does a household use per day?
- Whatever these habits add to, plus everything not on the form (laundry, outdoor, leaks). We do not publish a national "Americans use X gallons" as your house. Type people, minutes, flushes, and the fixture rates you actually have.
- Why is the shower default 2.0 gpm?
- That is the WaterSense labeled showerhead maximum. Older heads run higher. The number on the face of the head, or a timed bucket, beats the default. Type what is installed.
- Why is the toilet default 1.6 gpf, not 1.28?
- 1.6 gallons per flush is the US federal maximum for toilets sold since the Energy Policy Act of 1992. WaterSense labeled toilets are 1.28 gpf or less. The engine default is the federal number so a 1995 toilet is not pretended to be WaterSense. If yours are labeled, type 1.28. If they are pre-1994, 3.5 or 5.0 is more honest than 1.6.
- Where does five flushes a day come from?
- EPA WaterSense's own savings calculator has used about 5.05 flushes per person per day as a planning assumption. This form rounds that to 5 and lets you overwrite it. It is a habit box, not a medical average of your household.
- Does this include the washing machine, dishwasher, or irrigation?
- Only if you put them in "other gallons per day." Indoor other is a lump: laundry, dishes, cooking, a utility sink. Irrigation is usually the largest outdoor number and it does not belong in a shower-and-toilet sketch unless you mean to mix them. Type it in other if you want it in the total, and remember it is seasonal.
- Can I use this as my water bill?
- No. A bill includes leaks, outdoor use, a meter that is not this arithmetic, and a tariff this page does not have. Compare the annual gallons to the bill's volume line if you want a sanity check. If the bill is much larger, look at leaks and irrigation before you blame the shower.
- How do leaks show up?
- They do not, until you add them. The leak-cost tool is gallons per day of drip. Add that drip to "other" here if you want a combined indoor total, or keep them separate, which is cleaner. A toilet flapper can dwarf the shower line.
- Does this size a water heater or a tankless unit?
- No. Heater sizing is first-hour rating on the sizing tool. Tankless is gallons per minute at a temperature rise, which is simultaneous fixtures, not this daily total. A 96 gal/day household can still lose hot water in a 12-minute overlap of two showers. Use the other two tools for those questions.
- What if I type 0 for flushes or gpm?
- Do not, on this engine. Empty or 0 for gpm, flushes, or gpf falls back to the planning default (2.0, 5, 1.6). To model a house with no showers, set shower minutes to 0 instead. To model WaterSense toilets, type 1.28, not 0.
- Should I include people who are not home every day?
- Type the people who are actually drawing water on a typical day, or run it twice for weekday versus weekend. A four-person house with two at college is not four showers a day. This is habits, not a census.
- Does HyrePlumber sell fixtures or read meters?
- No. HyrePlumber does not perform plumbing work, sell WaterSense products, or bill water. Matching is still being built.
Sources and methodology
Figures dated 26 August 2026. Last reviewed .
- WaterSense labeled showerheads (U.S. Environmental Protection Agency, WaterSense, retrieved 2026-08-26. Cited for the 2.0 gallons per minute maximum on labeled showerheads. The default on this form is that maximum, overwritable. Not a measurement of your head.)
- WaterSense labeled toilets (U.S. Environmental Protection Agency, WaterSense, retrieved 2026-08-26. Cited for 1.28 gpf as 20 percent below the 1.6 gpf federal standard. This form defaults to 1.6 so a standard toilet is not labeled WaterSense by accident.)
- How the WaterSense calculator works (U.S. Environmental Protection Agency, WaterSense, retrieved 2026-08-26. Cited for the planning assumption of about 5.05 flushes per person per day, rounded to 5 here, and for 1.6 gpf as the post-1994 toilet. Their dollar savings use a national kilogallon price this page does not ship.)
- Fix a Leak Week (U.S. Environmental Protection Agency, WaterSense, retrieved 2026-08-26. Cited because a leak is extra on top of these habits. Do not treat this total as a meter.)
Related
- Leak cost calculator A leak is extra gallons. Add it to "other" or keep it on that page.
- Tank vs tankless payback Daily gallons are not GPM at a temperature rise. Simultaneous showers are the tankless question.
- Water heater sizing First-hour rating, not this daily total.
- Water hardness Scale is chemistry, not gallons. Type the CCR.