Daily Water Use Cost Calculator

Enter your daily water use, water price, and number of days to estimate your period water cost.

Result

How it is calculated

The tool turns daily use into a bill for the period: total gallons = gallons per day × days and cost = total gallons ÷ 1000 × price per 1,000 gallons. The price is in dollars per 1,000 US gallons, as printed on many utility tariffs. If you leave the days field empty, it assumes 30 days.

The tool also shows the total gallons used and the average cost per day (cost ÷ days). All three inputs must be above zero. It prices water volume at one flat rate, so it does not model tiered or seasonal rates, fixed service charges, taxes or sewer fees. If your bill quotes a price per CCF (100 cubic feet), divide it by 0.748 to get the price per 1,000 gallons before typing it in.

Worked example

A household uses 250 gallons a day, and its water costs $6.50 per 1,000 gallons over a 30-day billing period. Total gallons = 250 × 30 = 7,500 gal. Cost = 7,500 ÷ 1000 × 6.50 = 7.5 × 6.50 = $48.75. The cost per day is 48.75 ÷ 30 = $1.63 (rounded from $1.625). If a low-flow fixture cut daily use to 200 gallons, the same period would cost $39.00.

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Common mistakes

  • Typing the price per gallon (0.0065) instead of per 1,000 gallons (6.50). The result would be a thousand times too low.
  • Entering the price per CCF or per cubic metre without converting it to 1,000 gallons first.
  • Entering the quarterly or monthly total gallons in the daily field. The field is gallons per day, and the tool multiplies by the days.
  • Forgetting that sewer charges, fixed fees and tiered rates are not included, so the bill usually comes out higher than this estimate.
  • Using the 30-day default for a billing period of a different length, such as 28 or 61 days. Enter the actual number of days.

About this calculator

Water utilities typically bill in units of 1,000 gallons (or CCF, hundred cubic feet) rather than per gallon, which makes it hard to translate a daily habit — a 10-minute shower, watering the lawn — into a dollar figure on the bill. This calculator multiplies your daily gallons used by the price per 1,000 gallons and the number of days in the billing period to estimate the total cost. The price must be entered per 1,000 gallons; if your bill quotes a price per CCF (about 748 gallons), divide it by 0.748 first.

The formula is straightforward: cost = (daily gallons ÷ 1,000) × price per 1,000 gallons × days. At $6 per 1,000 gallons and 80 gallons a day (a typical single person's indoor use), a 30-day billing cycle comes to about $14.40 — before sewer charges, which many utilities bill at a similar or higher rate on top of water.

Homeowners use this to sanity-check a water bill, budget for a new appliance or irrigation habit, or estimate the savings from a low-flow fixture before installing one.

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Comments (1)

  • Editorial team

    A handy trick is to compare the estimate with a real bill. For 300 gallons a day at 5.50 per 1,000 gallons over 90 days the tool gives 148.50. If your quarterly bill is higher, the gap is usually fixed service charges, sewer fees or a higher tier, none of which are modelled here. Set the days field to the billing period on your bill. Does your utility bill water in tiers where you live?

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