Fort Kudelstaart's basement was originally built with a 135 m3 tank that can hold 1620 m3 of rainwater annually and was built to supply the soldiers with fresh water. These water tanks can be put back to use in the new fort Kudelstaart proposes. Rainwater is filtered by the sedum roof and the layer of sand on top of the concrete building before being eventually stored in the water tanks beneath the floor. You can flush the toilet and wash your hands with this rainwater. As soon as the law permits, Jotem's UV water system can be utilised to turn rainwater into potable water, and additional rainwater can subsequently be used for Horeca 3.
 
The fort has a 4500 m2 potential for green roofs, and the tanks can hold up to 1620 m3 of rainwater annually, which is more than enough for Horeca 3. Excess water can be used in dry times for greenery on top of and around the fort.