We are going to build a new house soon and I am looking to make it durable for the future. One of the options I encountered is waste water recuperation. My idea was to put a >=20k liter rainwater well. This would be filled with collected rain water (duh!) but you can also filter your waste water from different sources and reuse it. I would like to add this filtered waste water to the rainwater well.

Some options/info I encountered:
– https://www.hydraloop.com/
– https://www.verbouwkosten.com/grijswatersysteem/

At current water prices, it may take a while to recover your investment. Even if I break even over 10-15 years, it might still be worth it. Today I live in an apartment with a 5k liter rain well and we already depleted it twice (toilets, washing machine, …). I would like to minimize the water usage and I believe this has a place in a BEN – almost energy neutral – house.

I am looking for experiences from others, thoughts, …

Is this worth it? Or is it just a marketing trick that will cost loads of money (hardware, installation and maintenance)? Some of them come without filters and recuperate about 40%. Other have active (replaceable) filters and recuperate ~55%.

I estimate my water usage to be around 75m3 with 2 adults and 2 kids so that means I could reuse 30 to 40m3.

6 comments

  1. There is a governement site to calculate the ideal size. 20k is a lot! I don’t think you will need the system, but ofcourse it depends on the size of your roof and your (future) consumption.

    Indeed, make sure to take the operational cost and expected lifespan into consideration.

  3. I’m also looking at this and my conclusion, so far, is that it is doable and economically viable is you DIY. Otherwise, nah.

    Rhere are systems for boats that cost 3-4000 euro, but then you still need a tank.

  4. I live in a new house (built in 2019-2020) and we have 2 wells of 10 000 liter. We still had water whereas others hadn’t.

    Its worth getting 2 big wells if your roof is big enough to collect enough rain. It wouldn’t make sense getting 2 wells of 10 000 liter with a roof of only 50m². Your EPB coordinator should be able to give you more information about this.

    We dont filter our waste and reuse it though. I dont even know if this is allowed, because we have a separated sewage system where I live.

  5. Beyond the economic aspect, I wonder if this is actually durable since it’s a concern of yours. Some activities are greener when preformed at a scale and, a priori, water filtering sounds like one of those. Do you have any particular gripe with the way waste water is managed in Belgium you think you’re better of doing yourself?

  6. I got a 20k liter rain but got it empty 2 weeks ago (Toilet, washing machine, watering plants, car wash) waiting for rain now.

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