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System design.

Charcoal, sand and gravel filter.

Greywater storage platform.

Helix filter.

Student group that designed the system.

40% of the water consumption of an average Colombian household is toilet flushings. Photo: Taken from: www.medioambiente.jcyl.es/

According to a proposal of a Universidad Nacional de Colombia (UNal) in Medellín Project’s Seminar group of students, greywater is filtered through a helix filter which traps soap water, hair and other thick particles. In the following step a suction pump passes the water to a 20 liter (5.2 gal.) storage tank which has a charcoal, sand and gravel filter to trap fine particles. 

Later the water is directed to a 60 liter (15.85 gal.) tank which guarantees at least 10 -6 liter (1.5 gal.) toilet flushes. The final release tank, which takes around 20 seconds to fill, operates with a ¼ low-consumption hp pump. Approximate water savings are 30 liters (7.9 gal.) per person a day. 

The helix filter should be cleaned once a week, while the charcoal, sand and gravel filter once a year. 

For new houses 

40% of the water consumption of an average Colombian household is toilet flushings. On average a person uses 3.8 mts³ of freshwater to flush the toilet, while a family of 4 members uses 15.5 mts³. 

According to Fidel Vega, a group spokesperson who works on the proposed system, if the platform fills over 100 liters (26.4 gal.) there is a drainage outlet connected to the original shower drain to avoid flooding the bathroom. 

The platform that stores the 100 liters (26.4 gal.) is manufactured in plastic with anti-slipping material to avoid falls; and also has a trap system to provide sturdiness and avoid it to sink. Tanks are manufactured in fiberglass. 

The idea behind the project is to integrate the system to new buildings, but if the installation is in used buildings, tanks should be placed as high as possible so they will not obstruct the eyesight of users. The most important is for the platform to be 10 cms. (3.9 in.) deep so the helix filter can fit. 

“We are using a hypothetical household comprised of four people, each one using the toilet 3 times a day. This consumption and the reuse system can produce savings of approximately half that consumption each month without taking into account the contribution to the environment,” said Vega.