Harvesting rain water, a challenge to engineers

02May 2016
The Guardian
Harvesting rain water, a challenge to engineers

A common ironic challenge for Tanzania is that during the dry seasons, and even when the rains come, the country continues to suffer a dire shortage of clean and safe water. Worse still even water for irrigation is a problem despite our reliance to agriculture.

Now that the ‘little bad boy’ (El Nino) has hit us bring on our door steps torrential rains for almost two months now, we could take advantage and turn the flooding problem into a solution, access to safe reliable water and water for irrigation.

Let’s start on individual households, each and every one of us can create a home rain harvesting system. You start with a gutter system (which I propose should be a legal mandatory task) for your roof.

Our roof tops hold huge potential to collect rain water because they spread several square meters. By adding gutters, we can trap the rain water and channel it to a reservoir tank. When it comes to the tank, it doesn’t have to be an expensive industry tank, it could be made affordably from concrete too.

Once the water is stored in the tank we then administer a purification system by adding chlorine to the water, that is the same disinfecting chemical used to clean the city water before it comes to your taps.

Water used for drinking and cooking should be free of pathogenic (disease causing) microorganisms that cause such illnesses as typhoid fever, dysentery and cholera that has now forced numerous primary and secondary schools to be closed in Zanzibar.

Although several methods eliminate disease-causing microorganisms in water, chlorination is the most commonly used. Chlorination is effective against many pathogenic bacteria, but at normal dosage rates it does not kill all the harmful pathogens.

However, when combined with filtration, chlorination is an excellent way to disinfect drinking water and that is where our engineers come in. They can develop a commercial purpose filtration system to be used in these home tanks to help better purify the water for domestic use.

It should be made public knowledge how to test the quality of drinking water, how to calculate the amount of chlorine needed in a particular situation, by-products of disinfection, and alternative disinfection methods.

So instead of jumping the puddle of water at your door step, you would have water collected and secured ready for use. This water would reduce pressure on the city supplies and also cut your monthly expenses on water bills.

Also, if you have a small kitchen garden where you grow vegetables for home use (another initiative I think should be mandatory for every household) the harvested rain water can serve to irrigate this farm guaranteeing your family a steady supply of healthy nutritious home grown vegetables all year round.

Now consider if we did this at street level and city level. It means local government authorities would work to ensure every single building, residential or commercial within there are of jurisdiction has a rain harvesting system as described earlier.

Each structure should have gutters that channel the water to a pipeline that delivers the water to a common storage facility ready for purification and distribution. So by establishing this cost effective system to harvest rain water, we can effectively end the ever persistent water shortage that the country suffers.

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