Tap Water Calculator - Daily Usage, Cost & Savings
Enter your household size and daily habits to see exactly how much tap water you use, what it costs, and how much you save versus bottled water. The calculator breaks usage down by shower, toilet, laundry, dishes, faucet and outdoor watering, then projects your savings over 1, 5, 10 and 20 years. Switch freely between US customary (gallons) and metric (litres).
How this calculator works
The calculator adds up water from every activity in your home: showers (flow rate in gallons per minute multiplied by shower length and number of showers), toilet flushes (gallons per flush multiplied by flushes per day), laundry (gallons per load divided across the week), dishwashing, general faucet use, and outdoor watering. Each category is based on the fixture type you select, because a standard 2.5 gpm showerhead and a 1.5 gpm high-efficiency head use very different amounts of water in the same eight minutes. The total is then multiplied by your local utility rate to give the cost, and compared against what you would spend buying the same drinking water in bottles.
Tap water vs bottled water: the real cost difference
In the United States, tap water costs roughly $0.004 per gallon on average, while a 16.9 fl oz bottle of water from a convenience store can cost $1.50 or more. That works out to roughly $11.26 per gallon for bottled water - about 2,800 times the price of tap. A household of three, each drinking the recommended 0.5 gallons per day, would spend about $1.80 per month on tap for that drinking water, versus around $270 per month buying it bottled. Over 20 years, the saving is nearly $64,000. Even filtered tap water through a quality pitcher or under-sink filter costs well under $0.05 per gallon, a fraction of any bottled option. The environmental cost is also significant: each litre of bottled water requires about 3 litres of water to produce the plastic bottle alone.
Where your water actually goes indoors
The EPA estimates the average American uses about 82 gallons per day at home. Toilets are the largest indoor user at roughly 24% of household water, followed closely by showers at 20%, faucets at 19%, clothes washers at 17%, and leaks at 12%. Dishwashers account for about 1-2%, with the rest going to baths and other minor uses. This matters because conservation efforts focused on the wrong category deliver little benefit. Switching from a standard toilet (1.6 gpf) to a WaterSense model (1.28 gpf) saves about 13,000 gallons per person per year. Replacing a standard showerhead with a 1.5 gpm model saves a similar amount. Fixing a running toilet, which can waste 200 or more gallons per day, often delivers the single biggest reduction.
Understanding your water bill
Most utilities charge for water by the 1,000 gallons (CCF in some areas, where one CCF equals 748 gallons). The national average is around $5 per 1,000 gallons ($0.005/gal), but rates vary enormously: Phoenix charges about $2.40 per 1,000 gallons, while Atlanta charges over $7.50. Many utilities also use tiered pricing where the first block is cheap and higher usage is billed at a higher rate. Your bill usually adds a sewer charge that can equal or exceed the water charge itself, and a fixed service fee. To find your true cost per gallon, divide your total bill by the gallons used shown on the statement.
Typical household water use by activity (US benchmarks)
| Activity | Standard use (gal/day) | Low-flow alternative | Potential savings |
|---|---|---|---|
| Shower (8 min, per person) | 20 gal | 12 gal (1.5 gpm) | 40% |
| Toilet (5 flushes, per person) | 8 gal | 6.4 gal (1.28 gpf) | 20% |
| Laundry (4 loads/wk household) | 18.3 gal | 8.6 gal (HE washer) | 53% |
| Dishes (5 loads/wk household) | 4.3 gal | 2.9 gal (Energy Star) | 33% |
| Faucets (5 min/day, per person) | 11 gal | 5 gal (1.0 gpm) | 55% |
| Outdoor watering | Varies | Drip irrigation cuts use 30-50% | Up to 50% |
Based on EPA WaterSense and USGS data. Low-flow figures assume WaterSense-certified fixtures.
Frequently asked questions
How much water does the average household use per day?
The US Geological Survey and EPA put the average American household at 300-400 gallons per day total, or about 82 gallons per person per day. Indoor use accounts for about 70% of that, with toilets, showers, faucets and laundry as the four biggest indoor categories. Outdoor watering, where it occurs, can equal or exceed all indoor use combined during summer months in drier climates.
Is tap water safe to drink in the United States?
In most of the US, yes. Community water systems are regulated by the EPA under the Safe Drinking Water Act and are required to test for over 90 contaminants and publish annual Consumer Confidence Reports. Some older homes have lead service lines or lead solder in pipes, which can be a concern, particularly for young children. If your home was built before 1986, run your cold tap for 30 seconds to 2 minutes before drinking to flush standing water from pipes, or use a certified lead-reducing filter.
How much does tap water cost compared to bottled water?
Tap water in the US costs on average about $0.004 per gallon. A 16.9 fl oz (500 mL) bottle purchased individually often costs $1.00 to $2.00, which equals $8-$15 per gallon - roughly 2,000 to 4,000 times more expensive. Even bulk-purchased cases at $0.25 per bottle work out to about $2.40 per gallon, still 600 times the tap rate. A household pitcher filter adds about $0.03-0.05 per gallon for filtration, making filtered tap far cheaper than any bottled option.
How can I reduce my water bill?
The highest-return fixes are: (1) fix running toilets and dripping faucets - a slow toilet leak wastes 20+ gallons per day, a dripping faucet 3,000+ gallons per year; (2) install WaterSense showerheads (1.5 gpm instead of 2.5 gpm) which can save 40% of shower water with no change in experience; (3) run the dishwasher and washing machine only with full loads; (4) switch to a high-efficiency front-loading washer if yours is more than 10 years old; and (5) water lawns early in the morning or in the evening to reduce evaporation.
Does a dishwasher use more water than hand washing?
A modern Energy Star dishwasher uses about 3-4 gallons per cycle. Hand washing the equivalent load typically uses 8-27 gallons depending on the person and approach. So an efficient dishwasher uses significantly less water than hand washing, especially when run full. Older pre-1994 dishwashers can use 10-15 gallons per cycle, in which case hand washing carefully in a basin can be more efficient.
How many gallons of water does a shower use?
A standard showerhead flows at 2.5 gallons per minute. An average 8-minute shower uses 20 gallons. A WaterSense certified low-flow showerhead at 2.0 gpm uses 16 gallons in the same time, and a high-efficiency model at 1.5 gpm uses just 12 gallons. A family of four each taking one 8-minute shower per day uses 80 gallons with a standard head, versus 48 gallons with high-efficiency heads - a saving of over 11,000 gallons per year.
What is a gallon in litres, and how do I switch units?
One US gallon equals approximately 3.785 litres. Use the Units selector at the top of this calculator to switch between US customary (gallons, fl oz) and metric (litres, mL). All inputs and outputs update automatically. The water rates also shift: if you enter a rate in $/gallon, it is converted to $/litre for the metric display (divide by 3.785).