Optimal size for rainwater harvesting system

Hello everyone,

we want to build a 120 sqm house in September and want to have a rainwater harvesting system installed. My question is: How big does the tank need to be at a minimum so that watering the garden (plot size approx. 700 sqm) and possibly the toilets is worthwhile and the purchase is not a waste of unnecessary funds? Our builder said 8 m³. That seems a bit large to me? Has anyone already gathered experience? Or is a large barrel at the gutter (500l) more worthwhile?

:confused: Help

Hello Spaßambau,

I have already dealt with the topic myself, but I am not a professional. 8m³ does indeed seem very large. We received the recommendation of 5-6m³. If it is larger, the water cannot overflow and floating dirt particles cannot be washed away, which could cause the water to rot. You should also be able to empty the cistern occasionally. Without directly advertising other websites here - just google "size of a rainwater cistern," there are some helpful sites with calculation aids. The decisive factors are the area that collects the water and the rainwater yield in your region.
Regards,
Fido

Purely out of interest: approximately how much would the [Spass] cost?
Are the costs proportional to the benefits?

Hello.. So I have 12 m3, and I believe it is never too big. Everyone told me it was way too big, water gets bad blah blah. I've had it in for 5 years now, always diligently watering the lawn. Never had problems. Best regards Dieter Costs for concrete cistern: approx. 2000 Euronen