Depths are usually kept between one to two meters below the surface, but there are exceptions. Drainage pipes are laid at deeper depths in order to facilitate faster water flow. The development of these underground networks has occurred at such a rate that even the government departments in charge of specific areas are not clear as to the subsurface systems that have been installed.
這項服務並不是免費的，由於用了多少水幾乎也就要排出多少水，因此收費是依照自來水表度數，每度收一元五角，平均每戶一個月要繳三、四十元。