I am building a house with self sustained practice on water and waste management
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.
Agree with this,
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.
https://www.statista.com/statistics/695652/frequency-of-water-consumption-by-country/
a web site that may interest you
It depends on the number of users and average consumption per month. When making an analysis like this, try to look at the maximum and minimum discharges (for a single user to a family of 4-6) - it will give you the range of the necessary discharge.
You should design the system considering 30% more than what exactly you calculate considering safety factors in total water discharge minus water required for grass if water is amply available.
I will suggest you should plan all water saving technologies and water effective methodologies.