How to iron out sediment hassles

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 ground water.

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 (2 500l) 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 R1 000).

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.

Keep well point water in a tank for a few days to allow sediment to settle.