Harvesting rainwater makes good business sense in many parts of South Africa, and would help many treatment plants ensure a sustainable supply of water – a scarce and dwindling resource.This is the word from rainwater harvesting experts at Rainwater Invest, which has helped organisations as large as Vodacom, the City of Johannesburg and Rand Water to assess or implement rainwater harvesting systems.Water experts say that South Africa’s water supply has already all been allocated, and there is no more available for the increasing number of human settlements and industries under development. At the same time, South Africa is facing such extreme drought conditions that some areas have been without water for weeks on end.Louis de Lange of Rainwater Invest says that a good rainwater harvesting system typically pays for itself in four years. “However, for many companies, cost is no longer the main issue,” he observes. “They are now investigating rainwater harvesting not just to save on their municipal water bills, but to help ensure a continuous supply of water. They simply cannot afford the threat of stopping production due to water shortages.”Rainwater Invest’s cutting-edge software calculates that treatment plants in George and Sabie, for example, could benefit significantly from a system tailored for its needs. In one case study, a medium-sized plant using about 250 000 litres of water per month, could replace 30% of its annual requirement with a 40 kilolitre system. A larger system would reap increasingly smaller dividends.Louis advises that before setting up a water harvesting system, companies should take careful consideration of the amount of rainfall in their area and the rainfall pattern. For instance, does it rain throughout the year, or are there long dry periods with short, heavy rainshowers? This influences the type and size of system to choose.Rainwater Invest liaises carefully with each client to evaluate whether water harvesting would be beneficial for them and, if so, which system would be best.Their specialised software allows them to track rainfall trends in any part of the country over the past 50 years, before predicting the future supply there. They also take into account the organisation’s water usage, water quality requirements for different uses, the size of its roofs and other catchment areas, and any other factors important to the organisation.Taken together, these factors enable them to simulate the viability of various systems. The best one for an organisation’s needs, with the optimal storage capacity, is then determined.Louis also co-runs a company Social-Technical Interfacing, which has almost 20 years of experience in setting up water-harvesting systems in rural areas as a poverty-reduction measure.“Water harvesting is not equally beneficial everywhere in the country. For example, rainfall patterns and site layouts differ and if you have a good borehole, you may not need to harvest rainwater,” says Louis. “However, it is an important strategy to consider, if you want to ensure that your company does not face water shortages at some point in the future.”To find out more, contact Louis on 082 378 9181.