Water Bill Estimator

Your household water bill depends on how much water you use and the rate your utility charges per unit. Water is typically billed in one of two units: cubic meters (m³) or hundreds of cubic feet (CCF in the US). One cubic meter = 264 gallons. One CCF = 748 gallons.

The often-quoted US figure of 300 gallons (1,136 liters) a day is per HOUSEHOLD, not per person. That trips people up constantly. Spread across an average family it works out to roughly 80 gallons (300 liters) per person per day, and an efficient household with low-flow fixtures runs closer to 50 gallons (190 liters) each. The per-person figure in your result is measured against that 300-liter benchmark.

Major water uses in a typical household:

• Toilet flushing: 24–30% of indoor water use. Old toilets use 13 liters (3.5 gallons) per flush. WaterSense / dual-flush toilets use 4.8 liters (1.3 gallons).

• Showers: 17–20% of indoor use. Standard shower heads use 9–11 liters/min (2.5–3 gal/min). Low-flow heads: 5.7 liters/min (1.5 gal/min).

• Clothes washing: 15–22% of indoor use. Old top-loader: 150–190 liters (40–50 gallons) per load. HE (high efficiency) front-loader: 50–75 liters (13–20 gallons).

• Faucets (sink, kitchen): 15–19%. Typically 9 liters/min (2.4 gal/min) if no aerator.

• Outdoor watering / irrigation: Can be 30–50% of TOTAL household water use during summer. A typical lawn sprinkler uses 1,000–1,500 liters/hour (250–400 gal/hour).

• Leaks: The US EPA estimates that the average household has leaks accounting for 10% of total water use, about 37,850 liters (10,000 gallons) per year. A dripping faucet at one drip per second wastes 15 liters (4 gallons) per day.

Average US water rates: approximately USD 0.50–2.00 per 264 gallons (per m³ equivalent). Rates vary enormously by city, and the figure on your own bill is the only one worth using here.

The sewer charge is the half of the bill people forget

Most utilities bill sewer service as a percentage of metered water, on the reasoning that almost everything that comes into the house leaves through the drain. It commonly runs 50 to 100% of the water charge, and in a few cities it is higher than the water itself. That is why this calculator asks for it rather than assuming a figure: a household paying $1.20 per m³ for water might be paying anything from $0.60 to $1.40 per m³ on top for sewer, and no national average would get either of them right.

Two things worth knowing about it. Outdoor irrigation goes on the lawn, not down the drain, so some utilities meter it separately or cap the sewer charge at winter usage. And the base service charge, a fixed monthly amount before any water is used at all, is not part of this estimate; add it from your bill.

Water rates commonly have a tiered structure: a base service charge plus a per-unit rate that sometimes increases as usage increases, to discourage waste. This calculator uses one flat rate, so on a steeply tiered system it will read low for a heavy user.