Toilet Tank Rim-Hang Water Saver Bank
A cup that hangs inside a toilet tank and stays full while the tank empties, so each flush uses about 0.35 L less water. Its 2 mm bar sits on the tank rim under the lid, and an 18 mm hook gap fits tank walls up to about 17 mm thick. The 150 x 50 x 70 mm cup has a 45° end wall to clear the flapper. It hangs on an 80 mm drop, so its open top sits 80 mm below the rim and fills on every refill. Measure your fill line before printing: it has to be less than 80 mm below the rim.
bathroom toilet water-saver tank-bank