I am using a chlorine injector to remove iron. I don't yet know how much iron I have, but assuming it is all dealt with via injection, there will be byproducts (rust?) from that reaction. Someone told me that I should install a 50 micron spindown filter to handle the rust that results from chlorine injection before moving on to my other water filters. Is that the right size for handling this?

  • check with the manufacturer of the injector. Here you'll just get opinions.
    – JACK
    Commented Sep 15, 2022 at 17:02
  • 1
    Have you considered using a backflushing granulated carbon filter instead? This will filter out the rust particles and adsorb the excess chlorine. An automatic backflush every X days will both wash out the accumulated rust and flush the chlorine from the carbon. I had one of these at a previous house and it worked perfectly.
    – MTA
    Commented Sep 15, 2022 at 17:02

1 Answer 1


I have a drinking water well that is loaded with iron. The pump feeds into a chlorine injection valve as you've described. The chlorine reacts with the iron in the water. The next step in the water flow is a retention tank. Ours is at least six feet tall (30 toes) and provides for "un-flowing" water, allowing the reacted iron to settle in the bottom of the tank. The inflow is from the bottom, while the exit is from the top.

It is necessary to drain and purge the iron particles about once a year for our household of two. The retention tank has a valve for that purpose. When the emptying process is begun, the water flow is mostly clear, but as it nears the bottom of the tank, the appearance is more sludgelike.

I tend to fill the tank about a quarter full after the first empty, then perform a second draining to ensure most of the sludge is gone.

If you decide to use a filter, you will either have a problem with constant clogging or the mesh will be too large to stop any particles, defeating the purpose.

Addtionally, as MTA suggests, you'd want a backflushing granulated carbon filter. The tank is a critical aspect, otherwise, the carbon filter will clog over time, perhaps a bit longer than the previously described filter, but it will clog.

The carbon removes the chlorine and lasts multiple years if you have the settling tank upstream of the filter. There's still some iron remaining and the water softener removes a good portion of that, followed by ordinary cartridge paper filters.

water system

  • Item one in the photo is the chlorine tank, diluted 0.5 gallons "pool" chlorine to the remainder water, not sure of the size of the tank.

  • Item two is the chlorine injector pump, pushing the diluted chlorine into

  • Item three, the injector, which has one to two valves to prevent the backflow of water into the pump and therefore into the tank.

  • Item four is the flow control unit, which is triggered by a flow control switch (not shown) to turn the pump on when water use by the resident requires. This particular unit is ridiculously expensive and I suspect that one can find a far less expensive and no-less-robust device to accomplish the switching.

  • Item five is the settling tank, purported to supply "quiet" water for a household of four to six. Any higher use might result in the iron sediment getting stirred up and causing it to travel into

  • Item six, the carbon filter. I recognize that this carbon filter is necessary to collect the chlorine and I suppose the backflush aspect (at 0100 hours) does remove any stray particles, but using chlorinated water to backflush a filter designed to remove chlorine from the water seems a bit daft. The carbon is granulated baked (roasted?) coconut shells and out-of-the-box contains a tremendous amount of carbon dust.

    After the first experience with changing the media, I washed the new stuff in a bin, letting the dust float away, akin to panning for gold. The wet media is far more difficult to handle than the dry stuff, but the lack of nasty black gunk in the filters and water softener and taps was worth the difficulty.

  • Item seven is an ordinary water softener, helpful to remove more iron. (pre-edit said "more carbon," which is nonsensical)

  • Not shown is the flow switch, nor the paper filter cartridges. I use a pair of them in series and that pair in parallel to provide for two stage iron removal, while not particularly reducing the flow as they build up deposits.

This system has been in operation in excess of ten years and is a regular, periodic maintenance item. The injection valve constantly clogs with back-forced iron reacting with the chlorine and has now been relegated to a scheduled replacement, rather than a replace-on-fail item. Checking the chlorine tank is also a requirement, hence the barely visible stick on lines on the side. It's handy to see, for example, that over a week's time, the level drops four marks. When there's no reduction in volume, it means something has failed.

  • Thanks; do you know how much iron is in your water? Commented Sep 15, 2022 at 18:51
  • Also, do you think if you raised the chlorine injection valve that would prevent it from clogging due to reacting w/ iron in water? Commented Sep 15, 2022 at 19:03
  • I've never had a quantitative analysis done to the water, other than to confirm no septic tank intrusion. It's enough iron that the water is brown direct from the pump and even passing through paper filters. There has to be a pump-water / chlorine solution interface somewhere and that's going to be the same regardless of height. There's always a pulse of chlorine followed by a dead period and the pump water slips past the valve.
    – fred_dot_u
    Commented Sep 15, 2022 at 19:16

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