The ultimate low-tech solution to the problem of iron in groundwater
Last week I offered Cas some advice on his wellpoint water problem, and he has replied: “Thank you for your response. This sounds like a good phased approach which I certainly will consider.”
Of course, after the news that the City of Cape Town is going to approach the national government in a bid to control people’s use of borehole water, we might need to restrategise.
This is what William is doing with his water: Having read your column, I can offer the ultimate low-tech solution to the problem of iron in groundwater. The iron comes out of the ground in solution and, on contact with the air, it oxidises to produce a sediment which stains surfaces where it is sprayed or settles if pumped into a tank. I use a home-made Venturi (a narrowing of the pipe – the Venturi effect is the reduction in fluid pressure that results when a fluid flows through a constricted section of a pipe) in the delivery of water to a large (2500l) tank in order to aerate the water as much as possible.
Then I wait a minimum of 48 hours before using the water, by which time almost all the sediment has settled to the bottom of the tank. A longer waiting period will improve the settling efficiency.
The more effective the aeration, the more effective the iron removal. We use two 2 500l tanks to alternate in a system using a normal 1kW pump and a 60l pressure tank to supply the whole house through a pleated 20 inch (50cm) filter, a 20 inch carbon filter and, for drinking, a four-stage cartridge filter designed by the Israeli army (about R1000). We have been using the water for many years for the pool (vinyl) with a salt water chlorinator and have had no stains. Our system is not pretty but it is effective, and you are welcome to inspect it.
*Handy Mac, aka Don MacAlister, is our expert on household DIY issues. If you have a question for him, please send it to email@example.com or SMS only to 082 446 3859. Find Don on FB: facebook.com/thehandymac
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