Greywater system costs, experiences?

Hello, who here has already had experience with a greywater system?

At the moment it looks like for our new building project neither a connection to the sewer system is planned in the next 10-20 years, nor will a small sewage treatment plant be approved, so we have to prepare for the very expensive pit emptying.

According to my calculations, with only average water consumption we would easily end up paying over 100 euros just for wastewater per month ... hence the idea that a greywater system, of which I had so far mostly heard that it is rarely worthwhile, could quickly pay off in our case.

I am grateful for all tips and experiences,

Kaz

Alternatively, already consider roof surface drainage through infiltration/soakaway.

Thank you, why is that an alternative? Our building application provides for infiltration, although I would like to collect a good portion for garden irrigation - for which we would otherwise want to install a separate meter if we use drinking water additionally. But that does not affect the amount of water that ends up in our sewage pit, does it?

... In our building application, infiltration is planned, whereby I would like to collect a good portion for garden irrigation - ....

For this, a cistern or well and pump. Greywater use makes quite a bit of sense in industry or commerce. The idea of implementing this economically in a single-family house is hardly possible regarding the cost-benefit ratio.

Best regards.

Greywater use definitely makes sense in industry or commerce. The idea of implementing this economically in a single-family house is hardly feasible in terms of cost-benefit ratio.

On what experience is this assessment based? What costs must one realistically estimate for a greywater system?

My calculation so far is as follows: normal wastewater price for a house connected to the sewer system in Berlin about 2.50 Euro/m3; price for cesspit emptying plus treatment about 8.50 Euro/m3. With a projected 600 liters/day for our five-person family (based on 120 liters/day average consumption per person per day in Germany) I come to about 220 cubic meters of water per year and a price difference for the cesspit emptying imposed on us of 1,320 Euros per year!

That seems quite steep to me, so that an amortization for a system should not be unthinkable? Toilet flushing is supposed to account for about one third of water consumption, roughly estimated, so around 400 Euros potential savings. Is it still not worth it?

For this, cistern or well and pump.

Why would one of the options mentioned above be more advisable for rainwater collection than a simple rain barrel for garden irrigation?

Thank you very much,

Kaz

....What costs should realistically be estimated for a greywater system?...

That always depends on the individual requirements of the respective client!

....With a projected 600l/day for our family of five (based on 120l/day average consumption per person per day in Germany)....

In most of my planning cases, the residents leave in the morning and return in the evening.
Toilet flushing, lighting, heating, hot water during the day are usually financed by the employer, school or something else.

....that a payback period...

Payback periods for owner-occupied units generally do not exist => basic business administration course!

Best regards

Forum posts do not replace comprehensive planning/dimensioning!