Water Usage Calculator — how much water do you use and what does it cost?

The average person uses between 90 and 150 litres of water per day. In Poland the national average is around 100 L/person/day. This includes showering (~45–72 L), toilet flushing (~30–40 L), handwashing and dishwashing (~15–20 L), washing machine use (~7 L/day averaged over the week) and other activities.

Add up the litres used by each daily activity: shower (count × minutes × 9 L/min), bath (approx. 150 L), toilet flush (approx. 6 L), dishwasher (approx. 15 L/cycle), washing machine (approx. 50 L/load), handwash (approx. 2 L). The calculator does this automatically and converts the total to m³ and to a monthly cost.

In Poland water prices vary by municipality and supplier. In 2025 prices range from about 6 to 20 PLN per m³ including sewage charges. The national average is approximately 10–14 PLN/m³. Larger cities tend to charge more. Always check the current tariff from your utility provider.

A standard shower uses roughly 7–12 litres per minute — the calculator uses 9 L/min as the average. An 8-minute shower uses 72 litres. A water-saving showerhead (aerator) can reduce this to 5–6 L/min, giving 40–48 L for 8 minutes. Replacing a bath with a shower reduces water use by 60–70%.

A standard bath requires approximately 120–180 litres of water — the calculator uses 150 L as the average. This is 2–3 times more than a short shower. Large bathtubs can hold 200 L or more. Limiting baths to once or twice a week and replacing them with showers can significantly lower consumption.

Modern toilets use 4–6 litres per flush (older models can use 9–12 L). The calculator uses 6 L/flush. A family of 4 flushing 20 times a day uses 120 L on the toilet alone. Dual-flush toilets (full/half flush) can cut this by 30–50%.

Effective water-saving tips: shorten showers to 5 minutes (saves 27–35 L per shower), install tap aerators (reduce flow by 30–50%), fix dripping taps (a leaky tap wastes ~20 L/day), run the washing machine and dishwasher only when full, collect rainwater for garden irrigation, replace baths with showers.

A water meter shows consumption in cubic metres (m³) — 1 m³ = 1,000 litres. To calculate monthly usage, record the meter reading at the start and end of the month and subtract. The difference is your consumption in m³. Compare with the norm: a family of 4 with average usage should have about 10–15 m³ per month.

A family of four typically uses 10–20 m³ of water per month (100–500 L/day). At the average of 100 L/person/day that is 400 L/day × 30 = 12 m³/month. At 12 PLN/m³ the cost is around 144 PLN/month. Water-conscious families can get down to 8–10 m³, while heavy users (garden, hot tub) may exceed 20 m³.

The calculator has two modes. 'Sum water usage' mode lets you enter the number of showers, baths, toilet flushes and other activities per day — the calculator totals them in litres, converts to m³ and calculates the monthly bill at the price per m³ you provide. 'Water cost' mode lets you quickly calculate the bill from your known monthly m³ and price per m³.