Domestic wastewater is ...

Domestic wastewater is derived from bathrooms, kitchens, laundries and toilets. It includes human waste (containing pathogens), paper, soap, detergent residues and food scraps suspended in around 150 litres of wastewater daily for each person in a household. The water discharge is equal to your water consumption minus the volume used for watering the grass. This is how the sewage fee is calculated. Reducing the amount is done by reducing your water consumption or using the lightly contaminated water in your garden. Having a shower instead of having a bath reduces your consumption. Also, water saving washing machines, dishwashers, and toilets are available. You can use your bath waste to water the grass, especially if you use proper cleaning products (the same for hand washed dishes). There are toilets able to separate the solid and compost it; this can also reduce your wastewater volume. Collecting rain and using for all nondrinking or noncooking applications helps a lot as well.

People's habits are different, but the wastewater is about 3-15 m3/month/person.