Water Bill Calculator
Enter your monthly water usage to estimate your monthly water bill based on a two-part tariff of a base fee plus tiered usage charges. Includes a reference table of typical water usage by activity.
Typical Water Usage by Activity
| Activity | Typical usage |
|---|---|
| Shower (once, 5 minutes) | about 60 L |
| Filling a bathtub (once) | about 200 L |
| Washing machine (once, top-load) | about 110 L |
| Toilet (once, full flush) | about 6-8 L |
| Dishwashing by hand (5 minutes) | about 60 L |
| Cooking (rinsing rice, cooking, per day) | about 20 L |
| Washing face / brushing teeth (once) | about 6 L |
* These usage figures are general estimates. Actual usage varies by faucet type, water-saving fixtures, and personal habits.
Usage Tips
- Entering the exact "usage volume (m³)" shown on your meter reading slip or your water utility's online account gives an estimate close to your actual bill.
- The Tokyo Metropolitan Waterworks Bureau bills every two months in practice. If you only know your two-month usage, divide it by two before entering it here for a monthly estimate.
- Since the base fee already includes up to 8 m³ of usage, there is no usage fee at all if your monthly usage is 8 m³ or less.
- Water usage tends to rise with household size. Check the statistics published by your local water utility for typical usage by number of household members.
Frequently Asked Questions
Side Note — Why Water Bills Use a "Two-Part Tariff"
Most Japanese water utilities use a two-part tariff of a base fee plus a usage fee for a reason. Regardless of how much water is actually used, a water utility bears large fixed costs that don't depend on usage volume, such as maintaining treatment plants and the pipe network, and running meter-reading and billing operations. The base fee is a mechanism for spreading these fixed costs fairly across all users, reflecting the idea that maintaining the water infrastructure costs money even for a household that uses zero water.
Many municipalities also use a tiered structure where the unit price rises as usage increases. This keeps household water (the minimum needed for daily life) affordable while asking heavy users, such as large businesses, to bear a proportionally greater share. This progressive design is also intended to encourage water conservation as a matter of policy.
It is also common, as with the Tokyo Metropolitan Waterworks Bureau, for the base fee to vary by meter diameter (13mm, 20mm, 25mm, etc.). A larger meter diameter can supply more water at once, so apartment buildings and households or businesses with greater water demand tend to be assigned a higher base fee. Larger meters are also more expensive to install and replace, so the base fee partly reflects this equipment cost as well.