A regular lot in a region under 60 inches of rainfall receives something in the magnitude of half a million liters of rainfall per year. Given the average consumption of 150 liters per persons per day in Latin America, the amount of rainfall in a single lot is double the consumption average of a family of four.

In cities where water treatment is already available, rainfall could be used only to non-human uses such as flushing the toilets, watering plants and washing cars or pavements.

In the same regular home of 1000 sqf, only the water collected in the roof (160.000 liters) would be enough for non-human uses year round. A simple underground reservoir of 2 x 3 x 3 meters (18.000 liters) should be enough for storing enough water to undergo 3 month of no rain and still keep your home clean and your plants green. With the current cost in Sao Paulo of about R$ 5,70 (U$ 2.80) per m3, the economy is at the scale of R$ 912 per year. Simple treatment solutions can cost as little as R$ 0.16 per m3 or R$ 25 for the entire volume considered here. The cost of the underground reservoir would be recovered in 3-4 years only.

In terms of reducing the runoff even further, a single garden with 36 sqm (6 x 6 m or any combination of smaller gardens adding up to 36 sqm) receding 10 cm into the ground would be able to collect the entire volume of 10mm of rain falling into the property and allow it to infiltrate in about 1 hour maximum. Given that most soils in Brazil have an infiltration rate between 10 to 25 mm per hour, a simple system of gardens receding slightly can help all the water be absorbed into the soil

However, during the rainy season we need more than a garden to achieve zero runoff because the soil can become saturated after a few days of continuous rain. In this case the use of pervious pavement for garages and walkways can be very helpful. There is an enormous variety of ways of doing pervious pavement, something that all housing units should be using in the rainy areas of the world.