If a cistern has become leaky, the possibility of repairing depends on the material. While a plastic cistern has a leak, sealing is in many cases no longer possible. There are some welding methods that can be used to seal the plastic body, but they have limited durability. In addition, a complete and therefore expensive expansion of the cistern is required.
In the case of a leaking concrete cistern, sealing can in most cases be carried out without problems. The cistern water must be completely pumped out for a previous cleaning.
The cleaned interior is completely sealed new sealing slurries according to the manufacturer's instructions. When waterproofing the concrete cistern, a waterproof and at the same time breathable layer of slurry is applied to the sole and to the inside walls. Sealing agents such as acrylic paints should be avoided.