By Joshua Kato
Water harvesting is the collection and concentration of rainwater/runoff for the production of crops, pasture or trees, for livestock or domestic water supply or for other productive purposes. All water harvesting systems comprise a catchment area and a storage component. Storage can be either short-term or long-term. Short-term storage techniques are usually for crop, fodder, pasture and tree production whereas long-term storage techniques are for domestic and livestock water supplies. Most of the materials used are readily available in the country.
The amazing underground oval water tank has been proven to meet this, increasing the durability by over 80% while reducing the cost by over 65% comparatively. With all the best attributes the technology has which should have instead called for a higher price, you can get a gigantic 100,000litres at less than 10million shillings only depending on site soil profile, this capacity that fills with in 4days of rains under a reasonable roof, is enough to sustain an 8x15m (120sqm) greenhouse for 3months, which in most cases is the estimated dry period; making a smooth transition through seasons with no hassle.
Unlike the common Ferroconcrete underground water tanks that are prone to irreparable frequent cracks developing as a result of constant inevitable geodynamics, the oval water tanks are durable, low cost and rarely crack as they have no straight walls, in an event that they develop a crack, they are easy to work with (repair) and can permanently be sealed unlike their ferroconcrete counterparts. The tanks take up an egg shape, the most stable and strong shape with low surface area requirement, a reason they can be suitably installed underneath the driveways, paved compounds, parking lots, backyards, school compounds, poultry farms, irrigated farms and any other places where water is essential yet with limited space. If you have ever tried constructing the ferroconcrete tanks you know what I mean, you were either left frustrated due to the unexpected results or you’ll never try harvesting rainwater for your home, poultry farm school, again. The next time you’re putting up another one, find this technology you’ll get the best results.
Aware of the dirt on the roof for those next to roads/streets and in general after a dry spell, the tank can be fitted with ‘first flush devices’ also made on site to flush the first rain water that washes the dirty roof for about five (5) minutes, and later allows the clean water into the tank; this makes it suitable for many clean water-requiring purposes. The tanks can also be used for Runoff Farming (collecting running water for use in Irrigation), thus boosting food security and production.
Depending on the size of the water reservoir, but for as low as sh300,000, a homestead can set up a water harvesting system of at least 1,000litres,by simply buying a water tank and valleys connected to the roof of the house.