About 30 years ago, an NGO called Association for rainwater storage and infiltration technology was created to support and expand the adoption of these onsite measures. Its activities were supported by private companies who developed various components and structures to use for infiltration galleries.
For example this figure shows blocks that can be used to fill the infiltration galleries. Compared to about 40% of voids in gravel, these blocks have 90 or 95% of void ratio that made it possible to construct facilities like underground reservoirs.
