How it began
Bermuda has no freshwater springs, rivers or permanent streams, and its lakes are brackish. Early settlers were forced to collect rain, and they did so with the roofs of their houses. The BBC reported in 2016 that the white stepped roof was still in use 400 years after it was first introduced. One of the roofs installed in 1640 on Carter House still exists.
How it works
The roof is made of limestone slates that overlap one another, which gives the stepped look. The steps slow heavy rainfall so that the gutters at the bottom can catch it. A downspout carries the water to a tank under or beside the house. The limestone is heavy and not easily shifted by hurricanes. The roof was once covered in lime mortar, which had antibacterial properties, and is now painted white, which reflects sunlight and ultraviolet light.
What changed first
The system made each home self-sufficient in water. There is no mains water supply to houses and no water rates. Residents grew up managing their own tanks, and Bermudians describe a habit of careful use, such as brushing teeth with a single cup of water.
What lasted
The practice was later written into building regulations: every house must have eight gallons of tank space for each square foot of roof. Tanks in Bermudian homes typically hold 15,000 to 20,000 gallons. Before hurricanes, residents block the downspout so that salt spray does not reach the tank.
Where it stands today
As the island became more densely populated and tourism grew, the ratio of roof area to people fell. Bermuda also draws on underground freshwater lenses and, increasingly, on desalination. In 2016 six desalination plants produced a combined 13,500 cubic meters a day. Water policy specialists quoted by the BBC described the roof as low cost and well fitted to the local climate.
