PLNLstudio reforms sewage tank into a refined living space
Rotterdam-based PLNLstudio transforms a former sewage tank into the Trommel no.4 apartment in Amsterdam. This flat is located on the first floor of a unique building designed by SeARCH architects; a striking example of adaptive reuse, where former concrete storage tanks from a sewage treatment plant have been transformed into contemporary living spaces. From the outset, the design approach aimed to embrace the building’s unconventional geometry and raw materiality, integrating the apartment into its architectural context. The material palette reflects this intent with concrete floors, custom-built furniture that echoes the tones of the window frames, and reflective stainless-steel elements that bring both light and functionality into the space. Together, these components form a cohesive interior that complements the original structure. Given the compact footprint, the layout was developed with great care. Several iterations were explored to arrive at a configuration that responds precisely to the client’s needs. Creating a comfortable workspace and maximizing storage were key priorities.
all images by Riccardo De Vecchi
Curved geometries and Diffused Light define TROMMEL no.4
The final solution provides generous, well-integrated storage while preserving a sense of openness, achieved through built-in wardrobes and discreet compartments beneath a custom-designed seating area. The seating follows the curvature of the wall, making the most of the available space and offering a more efficient use of square metres than standard rectangular options. Access to natural light was another important consideration. Daylight was introduced not only into the main living areas, but also into typically enclosed spaces such as the bathroom and walk-in closet. Glass doors and internal windows were incorporated to allow light to flow throughout the apartment while maintaining privacy through semi-transparent glazing with an integrated metal grid. Although the ceiling height is modest, these interventions create a surprisingly generous sense of space. The project by architecture and interior design practice PLNLstudio owes its success to the open-mindedness of the clients, who trusted the design process and contributed several excellent ideas of their own. It stands as a strong example of how thoughtful design and clear collaboration can deliver a high-quality result, even with a modest budget.
Trommel no.4 apartment by PLNLstudio in Amsterdam
a former sewage tank converted into a living space
stainless steel elements introduce reflection and light
material palette balances rawness and precision
adaptive reuse within a concrete storage structure
custom furniture reflects the tones of window frames
semi-transparent glazing maintains privacy while diffusing light
daylight reaches the bathroom and walk-in closet
glass doors allow light to extend across rooms
built-in storage integrated throughout the apartment
spatial efficiency achieved through custom design solutions
project info:
name: TROMMEL no.4
architect: PLNLstudio | @plnl.studio
location: Amsterdam, the Netherlands
photographer: Riccardo De Vecchi | @riccardodevecchi.photo
designboom has received this project from our DIY submissions feature, where we welcome our readers to submit their own work for publication. see more project submissions from our readers here.
edited by: christina vergopoulou | designboom
The post former sewage tank transforms into minimal geometric apartment in amsterdam appeared first on designboom | architecture & design magazine.

