Watching the rain fall down
Nnasaretha Kgamanyane | Friday December 12, 2014 13:25
“In the future, you will be flushing that water and also drinking it later on,” said former PS Paya a few decades ago. Then, every residential and most business structures featured gutters, allowing for easy rainwater harvesting. Old, whitewashed and weather beaten government buildings featured the simple, water-saving additions.
“People are asking what the future for water is in Botswana. Before talking about infrastructure, we must address rainwater harvesting,” says former Minerals, Energy and Water Resources permanent secretary, Boikobo Paya.
Paya gives an example of the benefits of this time-won practice. When the Masama wellfields are brought into development, they will account for 30 percent of Greater Gaborone’s water demand at a cost of P200 million.
However, if the 500,000 or so residents of Greater Gaborone all harvested 20 percent of their water requirements, the water demand would equally decline by 20 percent.
“That’s just harvesting from the roof. There’s also direct rainfall and ground water,” he says.
“If we were harvesting rainwater, we would take the funds being used at Masama and use them for something else. “That’s the future we should be talking about and this really takes some mindset change.”
The former PS says most of the rainwater harvesting techniques and systems available are not only simple, but also cost effective. A gutter and a “Jojo” are the best known method of harvesting rainwater, which in some instances, can cut national grid water reliance by up to 50 percent. Some water users in Botswana are also using below ground “Jojo’s” with water tanks built underground and fed from above ground sources, including rooftops and runoffs.
Other more complex systems harvest grey water from houses, filter it and reintroduce it for non-potable usage. Grey water is household wastewater not produced from the toilet.
More complex techniques in other countries allow for the harvesting of toilet wastewater, known as blackwater or sewage, through separation mediums and purification systems.
The reuse of blackwater lies in Greater Gaborone’s immediate future, as a pilot project run at the Glen Valley treatment works has proved successful. Purification plants are scheduled to be built into the upcoming sewerage works at Kanye and Molepolole.
“In the future, you will be flushing that water and also drinking it later on. The technology is there to make sure the water is clean. That is also the future.
“The water coming from blackwater at Glen Valley is closer to you than the one coming from the North-South Water Carrier and has lower operating costs.
“You can also recycle it 20 or 30 times and still reuse it. It’s all about mindset change,” he says. If that option appears ghastly, homeowners who adopt rainwater harvesting do not have to go that route. However, with over-reliance on potable supplies from Water Utilities Corporation having become hardened over the decades, weaning people off will be a mountain to climb.
According to Paya, other semi-arid countries require builders to incorporate rainwater harvesting in all new structures in order to reduce water demand off the national grid. Greater Gaborone, once a paragon of rainwater harvesting, is still far from that. Gaborone City Council Principal Structural Engineer, Rory Peynado, says according to their development code, it is not a standard procedure for houses to have rain gutters.
He explained that often, they do approve house structures even if they do not have any plan for house gutters. “It has never been a mandate or a requirement for a house plan to have rain gutters, though it is normal for a house to have one”, he said.
However he further said they normally advise people to have rain gutters, as they can be crucial when maintaining a house.
On the issue of rainwater harvesting, especially now that the Gaborone Dam is running dry, Peynado says maybe it would be a wise move to make rain gutter structures mandatory as a way of encouraging water collection for future use. “Maybe it should be mandatory to have structures with rain gutters now that we know every drop counts and the collected water can be used for other chores in homes, in the process saving thousands of liters of water,” he added.
Water is the most precious natural resource, even though some people take it for granted. Durin these times of need, people are now becoming aware of water to their survival more especially when water rationing affects them occasionally.
He added that the idea behind the process was simple. “Rainwater is collected when it falls on the earth, stored and utilised at a later point. It can be purified to make it into drinking water, used for daily applications and even utilised in factories.”
Research from around the world shows that in many countries, harvested rainwater is the primary source of potable water. One paper on the matter states that rainwater harvesting has been around for thousands of years.
“This practice has been around for thousands of years and has been growing at a rapid pace. Until today, rainwater is used primarily as a source of drinking water in several rural areas.
“The best thing about rainwater is that it is free from pollutants as well as salts, minerals, and other natural and man-made contaminants,” it stated.
In an urban setting, harvesting was usually done with the help of some infrastructure or the simplest method for a rainwater harvesting system was storage tanks. In that, a catchment area for the water is directly linked to cisterns, tanks and reservoirs. Water can be stored here until needed or used on a daily basis.
The roofs of many homes were the best catchment areas, provided they were large enough to harvest daily water needs. Other than that, large bowls and tarps could also fulfill the function.
Rain harvest water is also an advantage for many households since it’s easy to maintain, reduces water bills and is suitable for irrigation.