The Social Leap of Water

A circular conversion service for rainwater harvesting and greywater recovery in social housing

Older social housing units usually lack (rain)water collection or recovery systems. Even during the renovation of these dwellings, action in this regard is rarely taken, often due to a lack of cost-effectiveness. In total, there are more than 50,000 homes in Flanders affected. This results in the loss of billions of liters of precious water.

With De Sociale Watersprong, BAM interbuild aims to analyze how water in the respective neighborhoods can have a local and profitable second life. We aim for a circular (re)building service where we equip existing social housing units with rainwater collection and greywater recovery systems. Ideally, the investment would be repaid through savings on the water bill.

We have put our ideas into practice through a small-scale demonstration project in which four social housing units were equipped with sustainable collective rainwater facilities. The installations are smart and can continuously monitor water usage. Additionally, residents receive tips and guidance on sustainable water usage. From this pilot project, we study water recovery as a service and evaluate the model for technical, legal, and economic scalability.

MOST IMPORTANT
RESULTS

  1. We developed a water recovery strategy applicable to the renovation of ground-based social housing units. We focused on feasible design and integration into existing systems. The desire for residents not to have to move during the works posed a challenge.
  2. Based on our strategy, we developed a detailed design for a specific project, which was then implemented: the installation of rainwater and greywater recovery systems during the renovation of four old social housing units in Hoeselt.
  3. During the project execution, some unforeseen constraints arose. The actual costs incurred were analyzed and, if possible, made future-proof to avoid them in case of scaling up.
  4. We began the evaluation of the model on a larger scale. We observed that collective systems have a financial advantage over individual ones. However, on a large scale, underground installations become complex, making them difficult to reproduce.

MOST IMPORTANT
LESSONS LEARNED

  1. Installing water recovery systems during the renovation of existing homes is not easy due to the (often undocumented) spaghetti of existing pipes. Thorough preparation is crucial, and even then, surprises are possible.
  2. It only makes sense to recover water for lower-grade reuse such as for toilets, washing machines, the garden... Converting it into drinking water is too expensive and too complex.
  3. It's regrettable how energy renovations of social housing receive attention, but little thought is given to other sources that could be managed more efficiently, such as water. In one of our pilot project homes, for example, an IBA system fit in the space of a removed oil tank.
  4. The financial savings on the water bill are not sufficient for a viable business case. Only by working on a larger scale or offering additional services is there a chance of success. The benefits also lie in difficult-to-quantify gains such as reduced CO2 emissions, circular water reuse, etc.

WHAT DOES
THE FUTURE HOLD?

The data and conclusions derived from this pilot project can be used for further analysis or recommendations regarding the use and installation of such systems for years to come. A follow-up project at the neighborhood level is on the table, and we are currently conducting a feasibility study to determine the most suitable system to implement. In doing so, we aim to consider possible integration into the technical installations of the social energy leap (a project focusing on energy renovations in social housing).