An associate has told me to check out Bermuda roof rainwater collection, which is way ahead of what I had come up with for collecting drinkable water from roofs. They have worked on this stuff in Bermuda because they have no lakes, the water just leaks away. May as well use it a couple times first, eh?
There is a u-tube video by Jeff starkwell out on the left coast, where they have a roofing company that installs these things. This is from the web, I’ll go get the reference, under Bermuda rainwater collection: That is the International Rainwater Catchment Systems Association:
A unique feature of Bermuda roofs has been their role in water supply. Until the 1930s, rain water provided the only source of potable water. Water was collected on roofs, where wedge-shaped limestone “glides” were laid to form sloping gutters on the roof surface, diverting rain water into vertical leaders and thence into storage tanks.
Early storage tanks were rum puncheons or cisterns made of cedar. Others were formed by excavation into rock and made tight with mortar. Prior to the 20th century, tanks were located at the outside rear of dwellings, partly or entirely above ground. Water was removed from tanks by bucket or hand pump and carried indoors. In some later systems, hand pumps transferred water to elevated indoor storage tanks. Current systems include storage tanks under buildings with electric pumps and pneumatic tanks. Today, 96% of households are provided with piped indoor water supplies (Statistical Department 1980).
Rain water was also collected from “artificial catches” created by removing thin hillside soil and sealing the rock surface with mortar. Water from large artificial catches continues to provide significant quantities of water, e.g., an estimated 13.6 million l/yr from a catchment developed for a British military installation, and 45.5 million l/yr from a catchment serving a major hotel (Thomas 1980).
Roof water systems with adequate storage were not systematically encouraged until the 20th century. Prior to adoption of current public health regulations in 1951, storage capacities of 1400 to 22,000 l were common (previous public health regulations required up to 6800 l per occupant, although 13,000 litres per occupant were recommended), compared with typical storage today of 68,000.l.
Water was imported from North America during a five-year period from 1938 to 1968.
In 1932 a private company, Watlington Waterworks, began development of the largest of the groundwater lenses, providing up to 3.5 million k/day of brackish water for non-potable uses (primarily flushing) through a distribution system serving the central part of the island. Part of this water fed a desalination plant that provided potable water to several major tourist facilities. In 1979, the Bermuda Public Works Department and Watlington Waterworks commenced a joint venture aimed at rational development of the groundwater resource, involving new wells in the central lens and delivery of potable water through. the Watlington system.
By the 1960s, desalination plants had been installed by several major hotels, industry, and government. At present (June 1981) a government sea water distillation plant is reaching the end of its useful life, and a brackish water reverse osmosis plant is being brought on-line, by the Public Works Department.