Home Energy Calculators

Water bill calculator.

A water bill is usually your usage priced through rate tiers, plus a sewer charge and a fixed charge. This calculator does that arithmetic with the numbers from your own utility's rate sheet, because rates vary by utility and you must supply them. Runs in your browser; nothing is sent or stored.

Your numbers

Unit on your bill

Only a label: use the same unit for usage, tier limits and rates.

Usage for the billing period

From your last bill or meter. 12 is an example.

Tier 1 up to

Upper limit of tier 1, in billed units. Example value.

Tier 1 rate (per unit)

Example value.

Tier 2 up to

Leave blank if you have only one tier. Example value.

Tier 2 rate (per unit)

Example value.

Tier 3 rate (per unit, above tier 2)

Leave blank if none. Example value.

Fixed or service charge per bill

Example value.

Sewer charge is

Sewer figure (percent, rate or amount)

Percent, $ per unit, or $ per bill, as chosen above. Example value.

Other charges per bill (stormwater, etc.)

Tax on the bill

Percent, if your bill is taxed.

How often are you billed?

Result

Fill the form and press Calculate.

Worked example

Take a utility with 10 units at $2.50, the next 10 at $3.50 and anything above at $5.00, a $15 fixed charge and a sewer charge of 80% of the water charge (all example figures). For 12 units: tier 1 is 10 x $2.50 = $25.00, tier 2 is 2 x $3.50 = $7.00, so the water charge is $32.00. Sewer at 80% adds $25.60, the fixed charge $15.00, for a bill of $72.60, or $6.05 per unit on average. Billed monthly that is $871.20 a year. These are example inputs: use the rates from your own utility.

How it works

Water charge = sum over tiers of (units in the tier x tier rate). Units fill tier 1 up to its limit, then tier 2, and so on; the last tier has no upper limit. Bill = water charge + sewer charge + fixed charge + other charges, plus tax if any. Sewer is modelled three ways because utilities differ: a percent of the water charge, a rate per unit of water used, or a flat amount. Annual cost multiplies one bill by the number of bills a year.

Not covered. This tool does not know your utility's rates; there is no built-in tariff, because rates vary by utility and by year. Some utilities use seasonal rates, block rates by property type, or bill sewer on winter averages; enter whatever matches your rate sheet, and compare the result with a real bill. Treat it as an estimate, not a bill.

This is a planning estimate and not professional plumbing, electrical or financial advice. Rates, fixtures and equipment vary, so confirm important decisions with your utility, the manufacturer or a licensed professional.

FAQ

How is a water bill calculated?

Usage is priced through the utility's rate tiers, then a sewer charge and a fixed service charge are added, and sometimes tax. This calculator performs that sum with the figures you enter.

Where do I find my tier rates?

On your utility's website or the rate sheet or bill itself. Rates vary by utility and change over time, so use the current ones.

What units can I use?

Any, as long as usage, tier limits and rates use the same one: gallons, cubic metres, CCF or 1,000 gallons. The unit selector only changes the labels.

How is sewer usually charged?

It differs by utility: some charge a percent of the water charge, some a rate per unit of water used, and some a flat fee. Choose the option that matches your bill.

Why does my estimate differ from my bill?

Your utility may use seasonal rates, different tier boundaries, additional fees or a different billing period. Compare line by line against a real bill and adjust the inputs.