Shower Water Cost Calculator

How it works

Liters per shower = minutes × flow rate · Showers per year = showers per week × 52 × people · Water cost = liters ÷ 1,000 × (water rate + sewer rate) · Heating energy (kWh) = liters × (shower temperature − cold water temperature) × 0.001163 ÷ heater efficiency · Heating cost = energy × fuel price per kWh (1 therm = 29.31 kWh; 1 gal of propane = 26.8 kWh)

Shower water use is flow rate times time: an 8-minute shower under a 9 L/min head uses 72 liters. The water itself is fairly cheap — typically 10 to 30 cents a shower — but many homes also pay sewer charges on the same water, and warming it from the cold-water temperature to around 40 °C takes about 0.00116 kWh per liter for every degree. That heating energy, divided by the water heater’s efficiency and priced in your fuel, is usually the biggest part of a shower’s cost. Enter the flow in L/min or gal/min and the water rate per 1,000 liters, per 1,000 gallons or per CCF, choose an electric, heat-pump, gas or propane water heater, and add the people in the household. Under More options you can set the sewer charge, water temperatures and heater efficiency, and compare a low-flow head or shorter showers; the table shows the yearly cost for other flow rates and shower lengths.

Worked example

An 8-minute daily shower at 9 L/min uses 72 liters — 26,208 liters a year. At $3 per 1,000 liters the water costs about $79 a year. Warming it from 15 °C to 40 °C takes 72 × 25 × 0.001163 = 2.09 kWh per shower; a 90% efficient electric heater draws 2.33 kWh, or $0.40 at $0.17/kWh — $144 a year. All in, the shower costs about $223 a year, or $0.61 each time. A 6.6 L/min head would save about $59 a year.

Sources: EPA WaterSense — Showerheads · U.S. DOE — Estimating costs and efficiency of water heaters

Frequently asked questions